diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-09 01:45:14 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-09 01:45:14 +0300 |
| commit | 46f1ec23a46940846f86a91c46f7119d8a8b5de1 (patch) | |
| tree | eb2b0bf4e17cf4a9a88e970cbffd829f3daba88f | |
| parent | 223cea6a4f0552b86fb25e3b8bbd00469816cd7a (diff) | |
| parent | 83086d654dd08c0f57381522e6819f421677706e (diff) | |
| download | linux-46f1ec23a46940846f86a91c46f7119d8a8b5de1.tar.xz | |
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
"The changes in this cycle are:
- RCU flavor consolidation cleanups and optmizations
- Documentation updates
- Miscellaneous fixes
- SRCU updates
- RCU-sync flavor consolidation
- Torture-test updates
- Linux-kernel memory-consistency-model updates, most notably the
addition of plain C-language accesses"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits)
tools/memory-model: Improve data-race detection
tools/memory-model: Change definition of rcu-fence
tools/memory-model: Expand definition of barrier
tools/memory-model: Do not use "herd" to refer to "herd7"
tools/memory-model: Fix comment in MP+poonceonces.litmus
Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic()
rcu: Don't return a value from rcu_assign_pointer()
rcu: Force inlining of rcu_read_lock()
rcu: Fix irritating whitespace error in rcu_assign_pointer()
rcu: Upgrade sync_exp_work_done() to smp_mb()
rcutorture: Upper case solves the case of the vanishing NULL pointer
torture: Suppress propagating trace_printk() warning
rcutorture: Dump trace buffer for callback pipe drain failures
torture: Add --trust-make to suppress "make clean"
torture: Make --cpus override idleness calculations
torture: Run kernel build in source directory
torture: Add function graph-tracing cheat sheet
torture: Capture qemu output
rcutorture: Tweak kvm options
rcutorture: Add trivial RCU implementation
...
61 files changed, 845 insertions, 466 deletions
diff --git a/Documentation/RCU/rcuref.txt b/Documentation/RCU/rcuref.txt index 613033ff2b9b..5e6429d66c24 100644 --- a/Documentation/RCU/rcuref.txt +++ b/Documentation/RCU/rcuref.txt @@ -12,6 +12,7 @@ please read on. Reference counting on elements of lists which are protected by traditional reader/writer spinlocks or semaphores are straightforward: +CODE LISTING A: 1. 2. add() search_and_reference() { { @@ -28,7 +29,8 @@ add() search_and_reference() release_referenced() delete() { { ... write_lock(&list_lock); - atomic_dec(&el->rc, relfunc) ... + if(atomic_dec_and_test(&el->rc)) ... + kfree(el); ... remove_element } write_unlock(&list_lock); ... @@ -44,6 +46,7 @@ search_and_reference() could potentially hold reference to an element which has already been deleted from the list/array. Use atomic_inc_not_zero() in this scenario as follows: +CODE LISTING B: 1. 2. add() search_and_reference() { { @@ -79,6 +82,7 @@ search_and_reference() code path. In such cases, the atomic_dec_and_test() may be moved from delete() to el_free() as follows: +CODE LISTING C: 1. 2. add() search_and_reference() { { @@ -114,6 +118,17 @@ element can therefore safely be freed. This in turn guarantees that if any reader finds the element, that reader may safely acquire a reference without checking the value of the reference counter. +A clear advantage of the RCU-based pattern in listing C over the one +in listing B is that any call to search_and_reference() that locates +a given object will succeed in obtaining a reference to that object, +even given a concurrent invocation of delete() for that same object. +Similarly, a clear advantage of both listings B and C over listing A is +that a call to delete() is not delayed even if there are an arbitrarily +large number of calls to search_and_reference() searching for the same +object that delete() was invoked on. Instead, all that is delayed is +the eventual invocation of kfree(), which is usually not a problem on +modern computer systems, even the small ones. + In cases where delete() can sleep, synchronize_rcu() can be called from delete(), so that el_free() can be subsumed into delete as follows: @@ -130,3 +145,7 @@ delete() kfree(el); ... } + +As additional examples in the kernel, the pattern in listing C is used by +reference counting of struct pid, while the pattern in listing B is used by +struct posix_acl. diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 1ab70c37921f..13e88fc00f01 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -153,7 +153,7 @@ rcupdate.rcu_task_stall_timeout This boot/sysfs parameter controls the RCU-tasks stall warning interval. A value of zero or less suppresses RCU-tasks stall warnings. A positive value sets the stall-warning interval - in jiffies. An RCU-tasks stall warning starts with the line: + in seconds. An RCU-tasks stall warning starts with the line: INFO: rcu_tasks detected stalls on tasks: diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 981651a8b65d..7e1a8721637a 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -212,7 +212,7 @@ synchronize_rcu() rcu_assign_pointer() - typeof(p) rcu_assign_pointer(p, typeof(p) v); + void rcu_assign_pointer(p, typeof(p) v); Yes, rcu_assign_pointer() -is- implemented as a macro, though it would be cool to be able to declare a function in this manner. @@ -220,9 +220,9 @@ rcu_assign_pointer() The updater uses this function to assign a new value to an RCU-protected pointer, in order to safely communicate the change - in value from the updater to the reader. This function returns - the new value, and also executes any memory-barrier instructions - required for a given CPU architecture. + in value from the updater to the reader. This macro does not + evaluate to an rvalue, but it does execute any memory-barrier + instructions required for a given CPU architecture. Perhaps just as important, it serves to document (1) which pointers are protected by RCU and (2) the point at which a diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5c7a0f5b0a2f..e6e806285703 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3752,6 +3752,12 @@ the propagation of recent CPU-hotplug changes up the rcu_node combining tree. + rcutree.use_softirq= [KNL] + If set to zero, move all RCU_SOFTIRQ processing to + per-CPU rcuc kthreads. Defaults to a non-zero + value, meaning that RCU_SOFTIRQ is used by default. + Specify rcutree.use_softirq=0 to use rcuc kthreads. + rcutree.rcu_fanout_exact= [KNL] Disable autobalancing of the rcu_node combining tree. This is used by rcutorture, and might diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt index dca3fb0554db..b3afe69d03a1 100644 --- a/Documentation/atomic_t.txt +++ b/Documentation/atomic_t.txt @@ -187,8 +187,14 @@ The barriers: smp_mb__{before,after}_atomic() -only apply to the RMW ops and can be used to augment/upgrade the ordering -inherent to the used atomic op. These barriers provide a full smp_mb(). +only apply to the RMW atomic ops and can be used to augment/upgrade the +ordering inherent to the op. These barriers act almost like a full smp_mb(): +smp_mb__before_atomic() orders all earlier accesses against the RMW op +itself and all accesses following it, and smp_mb__after_atomic() orders all +later accesses against the RMW op and all accesses preceding it. However, +accesses between the smp_mb__{before,after}_atomic() and the RMW op are not +ordered, so it is advisable to place the barrier right next to the RMW atomic +op whenever possible. These helper barriers exist because architectures have varying implicit ordering on their SMP atomic primitives. For example our TSO architectures @@ -212,7 +218,9 @@ Further, while something like: atomic_dec(&X); is a 'typical' RELEASE pattern, the barrier is strictly stronger than -a RELEASE. Similarly for something like: +a RELEASE because it orders preceding instructions against both the read +and write parts of the atomic_dec(), and against all following instructions +as well. Similarly, something like: atomic_inc(&X); smp_mb__after_atomic(); @@ -244,7 +252,8 @@ strictly stronger than ACQUIRE. As illustrated: This should not happen; but a hypothetical atomic_inc_acquire() -- (void)atomic_fetch_inc_acquire() for instance -- would allow the outcome, -since then: +because it would not order the W part of the RMW against the following +WRITE_ONCE. Thus: P1 P2 diff --git a/Documentation/core-api/circular-buffers.rst b/Documentation/core-api/circular-buffers.rst index 53e51caa3347..50966f66e398 100644 --- a/Documentation/core-api/circular-buffers.rst +++ b/Documentation/core-api/circular-buffers.rst @@ -3,7 +3,7 @@ Circular Buffers ================ :Author: David Howells <dhowells@redhat.com> -:Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> +:Author: Paul E. McKenney <paulmck@linux.ibm.com> Linux provides a number of features that can be used to implement circular diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index f70ebcdfe592..e4e07c8ab89e 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -3,7 +3,7 @@ ============================ By: David Howells <dhowells@redhat.com> - Paul E. McKenney <paulmck@linux.vnet.ibm.com> + Paul E. McKenney <paulmck@linux.ibm.com> Will Deacon <will.deacon@arm.com> Peter Zijlstra <peterz@infradead.org> diff --git a/Documentation/translations/ko_KR/memory-barriers.txt b/Documentation/translations/ko_KR/memory-barriers.txt index db0b9d8619f1..5f3c74dcad43 100644 --- a/Documentation/translations/ko_KR/memory-barriers.txt +++ b/Documentation/translations/ko_KR/memory-barriers.txt @@ -24,7 +24,7 @@ Documentation/memory-barriers.txt ========================= 저자: David Howells <dhowells@redhat.com> - Paul E. McKenney <paulmck@linux.vnet.ibm.com> + Paul E. McKenney <paulmck@linux.ibm.com> Will Deacon <will.deacon@arm.com> Peter Zijlstra <peterz@infradead.org> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 6e2377e6c1d6..e8eef38b2213 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -632,11 +632,18 @@ do { \ "IRQs not disabled as expected\n"); \ } while (0) +#define lockdep_assert_in_irq() do { \ + WARN_ONCE(debug_locks && !current->lockdep_recursion && \ + !current->hardirq_context, \ + "Not in hardirq as expected\n"); \ + } while (0) + #else # define might_lock(lock) do { } while (0) # define might_lock_read(lock) do { } while (0) # define lockdep_assert_irqs_enabled() do { } while (0) # define lockdep_assert_irqs_disabled() do { } while (0) +# define lockdep_assert_in_irq() do { } while (0) #endif #ifdef CONFIG_LOCKDEP diff --git a/include/linux/module.h b/include/linux/module.h index 188998d3dca9..1455812dd325 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -21,6 +21,7 @@ #include <linux/rbtree_latch.h> #include <linux/error-injection.h> #include <linux/tracepoint-defs.h> +#include <linux/srcu.h> #include <linux/percpu.h> #include <asm/module.h> @@ -450,6 +451,10 @@ struct module { unsigned int num_tracepoints; tracepoint_ptr_t *tracepoints_ptrs; #endif +#ifdef CONFIG_TREE_SRCU + unsigned int num_srcu_structs; + struct srcu_struct **srcu_struct_ptrs; +#endif #ifdef CONFIG_BPF_EVENTS unsigned int num_bpf_raw_events; struct bpf_raw_event_map *bpf_raw_events; diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index 03cb4b6f842e..2809b44cbbee 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -17,14 +17,18 @@ struct percpu_rw_semaphore { int readers_block; }; -#define DEFINE_STATIC_PERCPU_RWSEM(name) \ +#define __DEFINE_PERCPU_RWSEM(name, is_static) \ static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name); \ -static struct percpu_rw_semaphore name = { \ - .rss = __RCU_SYNC_INITIALIZER(name.rss, RCU_SCHED_SYNC), \ +is_static struct percpu_rw_semaphore name = { \ + .rss = __RCU_SYNC_INITIALIZER(name.rss), \ .read_count = &__percpu_rwsem_rc_##name, \ .rw_sem = __RWSEM_INITIALIZER(name.rw_sem), \ .writer = __RCUWAIT_INITIALIZER(name.writer), \ } +#define DEFINE_PERCPU_RWSEM(name) \ + __DEFINE_PERCPU_RWSEM(name, /* not static */) +#define DEFINE_STATIC_PERCPU_RWSEM(name) \ + __DEFINE_PERCPU_RWSEM(name, static) extern int __percpu_down_read(struct percpu_rw_semaphore *, int); extern void __percpu_up_read(struct percpu_rw_semaphore *); diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h index 6fc53a1345b3..9b83865d24f9 100644 --- a/include/linux/rcu_sync.h +++ b/include/linux/rcu_sync.h @@ -13,62 +13,44 @@ #include <linux/wait.h> #include <linux/rcupdate.h> -enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC }; - /* Structure to mediate between updaters and fastpath-using readers. */ struct rcu_sync { int gp_state; int gp_count; wait_queue_head_t gp_wait; - int cb_state; struct rcu_head cb_head; - - enum rcu_sync_type gp_type; }; -extern void rcu_sync_lockdep_assert(struct rcu_sync *); - /** * rcu_sync_is_idle() - Are readers permitted to use their fastpaths? * @rsp: Pointer to rcu_sync structure to use for synchronization * - * Returns true if readers are permitted to use their fastpaths. - * Must be invoked within an RCU read-side critical section whose - * flavor matches that of the rcu_sync struture. + * Returns true if readers are permitted to use their fastpaths. Must be + * invoked within some flavor of RCU read-side critical section. */ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) { -#ifdef CONFIG_PROVE_RCU - rcu_sync_lockdep_assert(rsp); -#endif - return !rsp->gp_state; /* GP_IDLE */ + RCU_LOCKDEP_WARN(!rcu_read_lock_held() && + !rcu_read_lock_bh_held() && + !rcu_read_lock_sched_held(), + "suspicious rcu_sync_is_idle() usage"); + return !READ_ONCE(rsp->gp_state); /* GP_IDLE */ } -extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type); +extern void rcu_sync_init(struct rcu_sync *); extern void rcu_sync_enter_start(struct rcu_sync *); extern void rcu_sync_enter(struct rcu_sync *); extern void rcu_sync_exit(struct rcu_sync *); extern void rcu_sync_dtor(struct rcu_sync *); -#define __RCU_SYNC_INITIALIZER(name, type) { \ +#define __RCU_SYNC_INITIALIZER(name) { \ .gp_state = 0, \ .gp_count = 0, \ .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \ - .cb_state = 0, \ - .gp_type = type, \ } -#define __DEFINE_RCU_SYNC(name, type) \ - struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type) - -#define DEFINE_RCU_SYNC(name) \ - __DEFINE_RCU_SYNC(name, RCU_SYNC) - -#define DEFINE_RCU_SCHED_SYNC(name) \ - __DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC) - -#define DEFINE_RCU_BH_SYNC(name) \ - __DEFINE_RCU_SYNC(name, RCU_BH_SYNC) +#define DEFINE_RCU_SYNC(name) \ + struct rcu_sync name = __RCU_SYNC_INITIALIZER(name) #endif /* _LINUX_RCU_SYNC_H_ */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index b25d20822e75..8f7167478c1d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -365,16 +365,15 @@ static inline void rcu_preempt_sleep_check(void) { } * other macros that it invokes. */ #define rcu_assign_pointer(p, v) \ -({ \ +do { \ uintptr_t _r_a_p__v = (uintptr_t)(v); \ - rcu_check_sparse(p, __rcu); \ + rcu_check_sparse(p, __rcu); \ \ if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \ WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \ else \ smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \ - _r_a_p__v; \ -}) +} while (0) /** * rcu_swap_protected() - swap an RCU and a regular pointer @@ -586,7 +585,7 @@ static inline void rcu_preempt_sleep_check(void) { } * read-side critical sections may be preempted and they may also block, but * only when acquiring spinlocks that are subject to priority inheritance. */ -static inline void rcu_read_lock(void) +static __always_inline void rcu_read_lock(void) { __rcu_read_lock(); __acquire(RCU); @@ -803,7 +802,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) /** * kfree_rcu() - kfree an object after a grace period. * @ptr: pointer to kfree - * @rcu_head: the name of the struct rcu_head within the type of @ptr. + * @rhf: the name of the struct rcu_head within the type of @ptr. * * Many rcu callbacks functions just call kfree() on the base structure. * These functions are trivial, but their size adds up, and furthermore @@ -826,9 +825,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * The BUILD_BUG_ON check must not involve any function calls, hence the * checks are done in macros here. */ -#define kfree_rcu(ptr, rcu_head) \ - __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) - +#define kfree_rcu(ptr, rhf) \ +do { \ + typeof (ptr) ___p = (ptr); \ + \ + if (___p) \ + __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ +} while (0) /* * Place this after a lock-acquisition primitive to guarantee that diff --git a/include/linux/sched.h b/include/linux/sched.h index 911675416b05..76adce49b5ad 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -565,7 +565,7 @@ union rcu_special { u8 blocked; u8 need_qs; u8 exp_hint; /* Hint for performance. */ - u8 pad; /* No garbage from compiler! */ + u8 deferred_qs; } b; /* Bits. */ u32 s; /* Set of bits. */ }; diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 7f7c8c050f63..9cfcc8a756ae 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -120,9 +120,17 @@ struct srcu_struct { * * See include/linux/percpu-defs.h for the rules on per-CPU variables. */ -#define __DEFINE_SRCU(name, is_static) \ - static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);\ - is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name##_srcu_data) +#ifdef MODULE +# define __DEFINE_SRCU(name, is_static) \ + is_static struct srcu_struct name; \ + struct srcu_struct * const __srcu_struct_##name \ + __section("___srcu_struct_ptrs") = &name +#else +# define __DEFINE_SRCU(name, is_static) \ + static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data); \ + is_static struct srcu_struct name = \ + __SRCU_STRUCT_INIT(name, name##_srcu_data) +#endif #define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */) #define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static) diff --git a/include/linux/torture.h b/include/linux/torture.h index 23d80db426d7..a620118385bb 100644 --- a/include/linux/torture.h +++ b/include/linux/torture.h @@ -66,7 +66,7 @@ int torture_shutdown_init(int ssecs, void (*cleanup)(void)); /* Task stuttering, which forces load/no-load transitions. */ bool stutter_wait(const char *title); -int torture_stutter_init(int s); +int torture_stutter_init(int s, int sgap); /* Initialization and cleanup. */ bool torture_init_begin(char *ttype, int v); diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index bf9dbffd46b1..cdbeff87fa99 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -101,7 +101,7 @@ static DEFINE_SPINLOCK(cgroup_idr_lock); */ static DEFINE_SPINLOCK(cgroup_file_kn_lock); -struct percpu_rw_semaphore cgroup_threadgroup_rwsem; +DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem); #define cgroup_assert_mutex_or_rcu_locked() \ RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ @@ -5666,7 +5666,6 @@ int __init cgroup_init(void) int ssid; BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16); - BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files)); BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files)); diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 78f61bfc6b79..97c367f0a9aa 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -46,7 +46,7 @@ static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) -static struct percpu_rw_semaphore dup_mmap_sem; +DEFINE_STATIC_PERCPU_RWSEM(dup_mmap_sem); /* Have a copy of original instruction */ #define UPROBE_COPY_INSN 0 @@ -2302,7 +2302,5 @@ void __init uprobes_init(void) for (i = 0; i < UPROBES_HASH_SZ; i++) mutex_init(&uprobes_mmap_mutex[i]); - BUG_ON(percpu_init_rwsem(&dup_mmap_sem)); - BUG_ON(register_die_notifier(&uprobe_exception_nb)); } diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 80a463d31a8d..c513031cd7e3 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -975,7 +975,7 @@ static int __init lock_torture_init(void) goto unwind; } if (stutter > 0) { - firsterr = torture_stutter_init(stutter); + firsterr = torture_stutter_init(stutter, stutter); if (firsterr) goto unwind; } diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index b6a9cc62099a..364d38a0c444 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -18,7 +18,7 @@ int __percpu_init_rwsem(struct percpu_rw_semaphore *sem, return -ENOMEM; /* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */ - rcu_sync_init(&sem->rss, RCU_SCHED_SYNC); + rcu_sync_init(&sem->rss); __init_rwsem(&sem->rw_sem, name, rwsem_key); rcuwait_init(&sem->writer); sem->readers_block = 0; diff --git a/kernel/module.c b/kernel/module.c index 80c7c09584cf..a2cee14a83f3 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3083,6 +3083,11 @@ static int find_module_sections(struct module *mod, struct load_info *info) sizeof(*mod->tracepoints_ptrs), &mod->num_tracepoints); #endif +#ifdef CONFIG_TREE_SRCU + mod->srcu_struct_ptrs = section_objs(info, "___srcu_struct_ptrs", + sizeof(*mod->srcu_struct_ptrs), + &mod->num_srcu_structs); +#endif #ifdef CONFIG_BPF_EVENTS mod->bpf_raw_events = section_objs(info, "__bpf_raw_tp_map", sizeof(*mod->bpf_raw_events), diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 390aab20115e..5290b01de534 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -446,6 +446,7 @@ void rcu_request_urgent_qs_task(struct task_struct *t); enum rcutorture_type { RCU_FLAVOR, RCU_TASKS_FLAVOR, + RCU_TRIVIAL_FLAVOR, SRCU_FLAVOR, INVALID_RCU_FLAVOR }; @@ -479,6 +480,10 @@ void do_trace_rcu_torture_read(const char *rcutorturename, #endif #endif +#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) +long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask); +#endif + #ifdef CONFIG_TINY_SRCU static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index efaa5b3f4d3f..fce4e7e6f502 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -299,6 +299,7 @@ struct rcu_torture_ops { int irq_capable; int can_boost; int extendables; + int slow_gps; const char *name; }; @@ -667,9 +668,51 @@ static struct rcu_torture_ops tasks_ops = { .fqs = NULL, .stats = NULL, .irq_capable = 1, + .slow_gps = 1, .name = "tasks" }; +/* + * Definitions for trivial CONFIG_PREEMPT=n-only torture testing. + * This implementation does not necessarily work well with CPU hotplug. + */ + +static void synchronize_rcu_trivial(void) +{ + int cpu; + + for_each_online_cpu(cpu) { + rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu)); + WARN_ON_ONCE(raw_smp_processor_id() != cpu); + } +} + +static int rcu_torture_read_lock_trivial(void) __acquires(RCU) +{ + preempt_disable(); + return 0; +} + +static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU) +{ + preempt_enable(); +} + +static struct rcu_torture_ops trivial_ops = { + .ttype = RCU_TRIVIAL_FLAVOR, + .init = rcu_sync_torture_init, + .readlock = rcu_torture_read_lock_trivial, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = rcu_torture_read_unlock_trivial, + .get_gp_seq = rcu_no_completed, + .sync = synchronize_rcu_trivial, + .exp_sync = synchronize_rcu_trivial, + .fqs = NULL, + .stats = NULL, + .irq_capable = 1, + .name = "trivial" +}; + static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old) { if (!cur_ops->gp_diff) @@ -1010,10 +1053,17 @@ rcu_torture_writer(void *arg) !rcu_gp_is_normal(); } rcu_torture_writer_state = RTWS_STUTTER; - if (stutter_wait("rcu_torture_writer")) + if (stutter_wait("rcu_torture_writer") && + !READ_ONCE(rcu_fwd_cb_nodelay) && + !cur_ops->slow_gps && + !torture_must_stop()) for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) - if (list_empty(&rcu_tortures[i].rtort_free)) - WARN_ON_ONCE(1); + if (list_empty(&rcu_tortures[i].rtort_free) && + rcu_access_pointer(rcu_torture_current) != + &rcu_tortures[i]) { + rcu_ftrace_dump(DUMP_ALL); + WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count); + } } while (!torture_must_stop()); /* Reset expediting back to unexpedited. */ if (expediting > 0) @@ -1358,8 +1408,9 @@ rcu_torture_stats_print(void) } pr_alert("%s%s ", torture_type, TORTURE_FLAG); - pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ", + pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ", rcu_torture_current, + rcu_torture_current ? "ver" : "VER", rcu_torture_current_version, list_empty(&rcu_torture_freelist), atomic_read(&n_rcu_torture_alloc), @@ -1661,6 +1712,17 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp) spin_unlock_irqrestore(&rcu_fwd_lock, flags); } +// Give the scheduler a chance, even on nohz_full CPUs. +static void rcu_torture_fwd_prog_cond_resched(void) +{ + if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) { + if (need_resched()) + schedule(); + } else { + cond_resched(); + } +} + /* * Free all callbacks on the rcu_fwd_cb_head list, either because the * test is over or because we hit an OOM event. @@ -1674,16 +1736,18 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void) for (;;) { spin_lock_irqsave(&rcu_fwd_lock, flags); rfcp = rcu_fwd_cb_head; - if (!rfcp) + if (!rfcp) { + spin_unlock_irqrestore(&rcu_fwd_lock, flags); break; + } rcu_fwd_cb_head = rfcp->rfc_next; if (!rcu_fwd_cb_head) rcu_fwd_cb_tail = &rcu_fwd_cb_head; spin_unlock_irqrestore(&rcu_fwd_lock, flags); kfree(rfcp); freed++; + rcu_torture_fwd_prog_cond_resched(); } - spin_unlock_irqrestore(&rcu_fwd_lock, flags); return freed; } @@ -1707,6 +1771,8 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries) } /* Tight loop containing cond_resched(). */ + WRITE_ONCE(rcu_fwd_cb_nodelay, true); + cur_ops->sync(); /* Later readers see above write. */ if (selfpropcb) { WRITE_ONCE(fcs.stop, 0); cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb); @@ -1724,7 +1790,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries) udelay(10); cur_ops->readunlock(idx); if (!fwd_progress_need_resched || need_resched()) - cond_resched(); + rcu_torture_fwd_prog_cond_resched(); } (*tested_tries)++; if (!time_before(jiffies, stopat) && @@ -1745,6 +1811,8 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries) WARN_ON(READ_ONCE(fcs.stop) != 2); destroy_rcu_head_on_stack(&fcs.rh); } + schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */ + WRITE_ONCE(rcu_fwd_cb_nodelay, false); } /* Carry out call_rcu() forward-progress testing. */ @@ -1765,6 +1833,8 @@ static void rcu_torture_fwd_prog_cr(void) if (READ_ONCE(rcu_fwd_emergency_stop)) return; /* Get out of the way quickly, no GP wait! */ + if (!cur_ops->call) + return; /* Can't do call_rcu() fwd prog without ->call. */ /* Loop continuously posting RCU callbacks. */ WRITE_ONCE(rcu_fwd_cb_nodelay, true); @@ -1805,7 +1875,7 @@ static void rcu_torture_fwd_prog_cr(void) rfcp->rfc_gps = 0; } cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr); - cond_resched(); + rcu_torture_fwd_prog_cond_resched(); } stoppedat = jiffies; n_launders_cb_snap = READ_ONCE(n_launders_cb); @@ -1814,7 +1884,6 @@ static void rcu_torture_fwd_prog_cr(void) cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */ (void)rcu_torture_fwd_prog_cbfree(); - WRITE_ONCE(rcu_fwd_cb_nodelay, false); if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) { WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED); pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n", @@ -1825,6 +1894,8 @@ static void rcu_torture_fwd_prog_cr(void) n_max_gps, n_max_cbs, cver, gps); rcu_torture_fwd_cb_hist(); } + schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */ + WRITE_ONCE(rcu_fwd_cb_nodelay, false); } @@ -2240,7 +2311,7 @@ rcu_torture_init(void) int firsterr = 0; static struct rcu_torture_ops *torture_ops[] = { &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops, - &busted_srcud_ops, &tasks_ops, + &busted_srcud_ops, &tasks_ops, &trivial_ops, }; if (!torture_init_begin(torture_type, verbose)) @@ -2363,7 +2434,10 @@ rcu_torture_init(void) if (stutter < 0) stutter = 0; if (stutter) { - firsterr = torture_stutter_init(stutter * HZ); + int t; + + t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ; + firsterr = torture_stutter_init(stutter * HZ, t); if (firsterr) goto unwind; } diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 9b761e546de8..cf0e886314f2 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -831,8 +831,8 @@ static void srcu_leak_callback(struct rcu_head *rhp) * srcu_read_lock(), and srcu_read_unlock() that are all passed the same * srcu_struct structure. */ -void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp, - rcu_callback_t func, bool do_norm) +static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp, + rcu_callback_t func, bool do_norm) { unsigned long flags; int idx; @@ -1310,3 +1310,68 @@ void __init srcu_init(void) queue_work(rcu_gp_wq, &ssp->work.work); } } + +#ifdef CONFIG_MODULES + +/* Initialize any global-scope srcu_struct structures used by this module. */ +static int srcu_module_coming(struct module *mod) +{ + int i; + struct srcu_struct **sspp = mod->srcu_struct_ptrs; + int ret; + + for (i = 0; i < mod->num_srcu_structs; i++) { + ret = init_srcu_struct(*(sspp++)); + if (WARN_ON_ONCE(ret)) + return ret; + } + return 0; +} + +/* Clean up any global-scope srcu_struct structures used by this module. */ +static void srcu_module_going(struct module *mod) +{ + int i; + struct srcu_struct **sspp = mod->srcu_struct_ptrs; + + for (i = 0; i < mod->num_srcu_structs; i++) + cleanup_srcu_struct(*(sspp++)); +} + +/* Handle one module, either coming or going. */ +static int srcu_module_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + struct module *mod = data; + int ret = 0; + + switch (val) { + case MODULE_STATE_COMING: + ret = srcu_module_coming(mod); + break; + case MODULE_STATE_GOING: + srcu_module_going(mod); + break; + default: + break; + } + return ret; +} + +static struct notifier_block srcu_module_nb = { + .notifier_call = srcu_module_notify, + .priority = 0, +}; + +static __init int init_srcu_module_notifier(void) +{ + int ret; + + ret = register_module_notifier(&srcu_module_nb); + if (ret) + pr_warn("Failed to register srcu module notifier\n"); + return ret; +} +late_initcall(init_srcu_module_notifier); + +#endif /* #ifdef CONFIG_MODULES */ diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c index a8304d90573f..d4558ab7a07d 100644 --- a/kernel/rcu/sync.c +++ b/kernel/rcu/sync.c @@ -10,65 +10,18 @@ #include <linux/rcu_sync.h> #include <linux/sched.h> -#ifdef CONFIG_PROVE_RCU -#define __INIT_HELD(func) .held = func, -#else -#define __INIT_HELD(func) -#endif - -static const struct { - void (*sync)(void); - void (*call)(struct rcu_head *, void (*)(struct rcu_head *)); - void (*wait)(void); -#ifdef CONFIG_PROVE_RCU - int (*held)(void); -#endif -} gp_ops[] = { - [RCU_SYNC] = { - .sync = synchronize_rcu, - .call = call_rcu, - .wait = rcu_barrier, - __INIT_HELD(rcu_read_lock_held) - }, - [RCU_SCHED_SYNC] = { - .sync = synchronize_rcu, - .call = call_rcu, - .wait = rcu_barrier, - __INIT_HELD(rcu_read_lock_sched_held) - }, - [RCU_BH_SYNC] = { - .sync = synchronize_rcu, - .call = call_rcu, - .wait = rcu_barrier, - __INIT_HELD(rcu_read_lock_bh_held) - }, -}; - -enum { GP_IDLE = 0, GP_PENDING, GP_PASSED }; -enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY }; +enum { GP_IDLE = 0, GP_ENTER, GP_PASSED, GP_EXIT, GP_REPLAY }; #define rss_lock gp_wait.lock -#ifdef CONFIG_PROVE_RCU -void rcu_sync_lockdep_assert(struct rcu_sync *rsp) -{ - RCU_LOCKDEP_WARN(!gp_ops[rsp->gp_type].held(), - "suspicious rcu_sync_is_idle() usage"); -} - -EXPORT_SYMBOL_GPL(rcu_sync_lockdep_assert); -#endif - /** * rcu_sync_init() - Initialize an rcu_sync structure * @rsp: Pointer to rcu_sync structure to be initialized - * @type: Flavor of RCU with which to synchronize rcu_sync structure */ -void rcu_sync_init(struct rcu_sync *rsp, enum rcu_sync_type type) +void rcu_sync_init(struct rcu_sync *rsp) { memset(rsp, 0, sizeof(*rsp)); init_waitqueue_head(&rsp->gp_wait); - rsp->gp_type = type; } /** @@ -86,56 +39,26 @@ void rcu_sync_enter_start(struct rcu_sync *rsp) rsp->gp_state = GP_PASSED; } -/** - * rcu_sync_enter() - Force readers onto slowpath - * @rsp: Pointer to rcu_sync structure to use for synchronization - * - * This function is used by updaters who need readers to make use of - * a slowpath during the update. After this function returns, all - * subsequent calls to rcu_sync_is_idle() will return false, which - * tells readers to stay off their fastpaths. A later call to - * rcu_sync_exit() re-enables reader slowpaths. - * - * When called in isolation, rcu_sync_enter() must wait for a grace - * period, however, closely spaced calls to rcu_sync_enter() can - * optimize away the grace-period wait via a state machine implemented - * by rcu_sync_enter(), rcu_sync_exit(), and rcu_sync_func(). - */ -void rcu_sync_enter(struct rcu_sync *rsp) -{ - bool need_wait, need_sync; - spin_lock_irq(&rsp->rss_lock); - need_wait = rsp->gp_count++; - need_sync = rsp->gp_state == GP_IDLE; - if (need_sync) - rsp->gp_state = GP_PENDING; - spin_unlock_irq(&rsp->rss_lock); +static void rcu_sync_func(struct rcu_head *rhp); - WARN_ON_ONCE(need_wait && need_sync); - if (need_sync) { - gp_ops[rsp->gp_type].sync(); - rsp->gp_state = GP_PASSED; - wake_up_all(&rsp->gp_wait); - } else if (need_wait) { - wait_event(rsp->gp_wait, rsp->gp_state == GP_PASSED); - } else { - /* - * Possible when there's a pending CB from a rcu_sync_exit(). - * Nobody has yet been allowed the 'fast' path and thus we can - * avoid doing any sync(). The callback will get 'dropped'. - */ - WARN_ON_ONCE(rsp->gp_state != GP_PASSED); - } +static void rcu_sync_call(struct rcu_sync *rsp) +{ + call_rcu(&rsp->cb_head, rcu_sync_func); } /** * rcu_sync_func() - Callback function managing reader access to fastpath * @rhp: Pointer to rcu_head in rcu_sync structure to use for synchronization * - * This function is passed to one of the call_rcu() functions by + * This function is passed to call_rcu() function by rcu_sync_enter() and * rcu_sync_exit(), so that it is invoked after a grace period following the - * that invocation of rcu_sync_exit(). It takes action based on events that + * that invocation of enter/exit. + * + * If it is called by rcu_sync_enter() it signals that all the readers were + * switched onto slow path. + * + * If it is called by rcu_sync_exit() it takes action based on events that * have taken place in the meantime, so that closely spaced rcu_sync_enter() * and rcu_sync_exit() pairs need not wait for a grace period. * @@ -152,35 +75,88 @@ static void rcu_sync_func(struct rcu_head *rhp) struct rcu_sync *rsp = container_of(rhp, struct rcu_sync, cb_head); unsigned long flags; - WARN_ON_ONCE(rsp->gp_state != GP_PASSED); - WARN_ON_ONCE(rsp->cb_state == CB_IDLE); + WARN_ON_ONCE(READ_ONCE(rsp->gp_state) == GP_IDLE); + WARN_ON_ONCE(READ_ONCE(rsp->gp_state) == GP_PASSED); spin_lock_irqsave(&rsp->rss_lock, flags); if (rsp->gp_count) { /* - * A new rcu_sync_begin() has happened; drop the callback. + * We're at least a GP after the GP_IDLE->GP_ENTER transition. */ - rsp->cb_state = CB_IDLE; - } else if (rsp->cb_state == CB_REPLAY) { + WRITE_ONCE(rsp->gp_state, GP_PASSED); + wake_up_locked(&rsp->gp_wait); + } else if (rsp->gp_state == GP_REPLAY) { /* - * A new rcu_sync_exit() has happened; requeue the callback - * to catch a later GP. + * A new rcu_sync_exit() has happened; requeue the callback to + * catch a later GP. */ - rsp->cb_state = CB_PENDING; - gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func); + WRITE_ONCE(rsp->gp_state, GP_EXIT); + rcu_sync_call(rsp); } else { /* - * We're at least a GP after rcu_sync_exit(); eveybody will now - * have observed the write side critical section. Let 'em rip!. + * We're at least a GP after the last rcu_sync_exit(); eveybody + * will now have observed the write side critical section. + * Let 'em rip!. */ - rsp->cb_state = CB_IDLE; - rsp->gp_state = GP_IDLE; + WRITE_ONCE(rsp->gp_state, GP_IDLE); } spin_unlock_irqrestore(&rsp->rss_lock, flags); } /** - * rcu_sync_exit() - Allow readers back onto fast patch after grace period + * rcu_sync_enter() - Force readers onto slowpath + * @rsp: Pointer to rcu_sync structure to use for synchronization + * + * This function is used by updaters who need readers to make use of + * a slowpath during the update. After this function returns, all + * subsequent calls to rcu_sync_is_idle() will return false, which + * tells readers to stay off their fastpaths. A later call to + * rcu_sync_exit() re-enables reader slowpaths. + * + * When called in isolation, rcu_sync_enter() must wait for a grace + * period, however, closely spaced calls to rcu_sync_enter() can + * optimize away the grace-period wait via a state machine implemented + * by rcu_sync_enter(), rcu_sync_exit(), and rcu_sync_func(). + */ +void rcu_sync_enter(struct rcu_sync *rsp) +{ + int gp_state; + + spin_lock_irq(&rsp->rss_lock); + gp_state = rsp->gp_state; + if (gp_state == GP_IDLE) { + WRITE_ONCE(rsp->gp_state, GP_ENTER); + WARN_ON_ONCE(rsp->gp_count); + /* + * Note that we could simply do rcu_sync_call(rsp) here and + * avoid the "if (gp_state == GP_IDLE)" block below. + * + * However, synchronize_rcu() can be faster if rcu_expedited + * or rcu_blocking_is_gp() is true. + * + * Another reason is that we can't wait for rcu callback if + * we are called at early boot time but this shouldn't happen. + */ + } + rsp->gp_count++; + spin_unlock_irq(&rsp->rss_lock); + + if (gp_state == GP_IDLE) { + /* + * See the comment above, this simply does the "synchronous" + * call_rcu(rcu_sync_func) which does GP_ENTER -> GP_PASSED. + */ + synchronize_rcu(); + rcu_sync_func(&rsp->cb_head); + /* Not really needed, wait_event() would see GP_PASSED. */ + return; + } + + wait_event(rsp->gp_wait, READ_ONCE(rsp->gp_state) >= GP_PASSED); +} + +/** + * rcu_sync_exit() - Allow readers back onto fast path after grace period * @rsp: Pointer to rcu_sync structure to use for synchronization * * This function is used by updaters who have completed, and can therefore @@ -191,13 +167,16 @@ static void rcu_sync_func(struct rcu_head *rhp) */ void rcu_sync_exit(struct rcu_sync *rsp) { + WARN_ON_ONCE(READ_ONCE(rsp->gp_state) == GP_IDLE); + WARN_ON_ONCE(READ_ONCE(rsp->gp_count) == 0); + spin_lock_irq(&rsp->rss_lock); if (!--rsp->gp_count) { - if (rsp->cb_state == CB_IDLE) { - rsp->cb_state = CB_PENDING; - gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func); - } else if (rsp->cb_state == CB_PENDING) { - rsp->cb_state = CB_REPLAY; + if (rsp->gp_state == GP_PASSED) { + WRITE_ONCE(rsp->gp_state, GP_EXIT); + rcu_sync_call(rsp); + } else if (rsp->gp_state == GP_EXIT) { + WRITE_ONCE(rsp->gp_state, GP_REPLAY); } } spin_unlock_irq(&rsp->rss_lock); @@ -209,18 +188,19 @@ void rcu_sync_exit(struct rcu_sync *rsp) */ void rcu_sync_dtor(struct rcu_sync *rsp) { - int cb_state; + int gp_state; - WARN_ON_ONCE(rsp->gp_count); + WARN_ON_ONCE(READ_ONCE(rsp->gp_count)); + WARN_ON_ONCE(READ_ONCE(rsp->gp_state) == GP_PASSED); spin_lock_irq(&rsp->rss_lock); - if (rsp->cb_state == CB_REPLAY) - rsp->cb_state = CB_PENDING; - cb_state = rsp->cb_state; + if (rsp->gp_state == GP_REPLAY) + WRITE_ONCE(rsp->gp_state, GP_EXIT); + gp_state = rsp->gp_state; spin_unlock_irq(&rsp->rss_lock); - if (cb_state != CB_IDLE) { - gp_ops[rsp->gp_type].wait(); - WARN_ON_ONCE(rsp->cb_state != CB_IDLE); + if (gp_state != GP_IDLE) { + rcu_barrier(); + WARN_ON_ONCE(rsp->gp_state != GP_IDLE); } } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 980ca3ca643f..a14e5fbbea46 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -51,6 +51,12 @@ #include <linux/tick.h> #include <linux/sysrq.h> #include <linux/kprobes.h> +#include <linux/gfp.h> +#include <linux/oom.h> +#include <linux/smpboot.h> +#include <linux/jiffies.h> +#include <linux/sched/isolation.h> +#include "../time/tick-internal.h" #include "tree.h" #include "rcu.h" @@ -92,6 +98,9 @@ struct rcu_state rcu_state = { /* Dump rcu_node combining tree at boot to verify correct setup. */ static bool dump_tree; module_param(dump_tree, bool, 0444); +/* By default, use RCU_SOFTIRQ instead of rcuc kthreads. */ +static bool use_softirq = 1; +module_param(use_softirq, bool, 0444); /* Control rcu_node-tree auto-balancing at boot time. */ static bool rcu_fanout_exact; module_param(rcu_fanout_exact, bool, 0444); @@ -138,7 +147,6 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf); static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf); static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); static void invoke_rcu_core(void); -static void invoke_rcu_callbacks(struct rcu_data *rdp); static void rcu_report_exp_rdp(struct rcu_data *rdp); static void sync_sched_exp_online_cleanup(int cpu); @@ -368,19 +376,33 @@ static void __maybe_unused rcu_momentary_dyntick_idle(void) } /** - * rcu_is_cpu_rrupt_from_idle - see if idle or immediately interrupted from idle + * rcu_is_cpu_rrupt_from_idle - see if interrupted from idle * - * If the current CPU is idle or running at a first-level (not nested) + * If the current CPU is idle and running at a first-level (not nested) * interrupt from idle, return true. The caller must have at least * disabled preemption. */ static int rcu_is_cpu_rrupt_from_idle(void) { - return __this_cpu_read(rcu_data.dynticks_nesting) <= 0 && - __this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 1; + /* Called only from within the scheduling-clock interrupt */ + lockdep_assert_in_irq(); + + /* Check for counter underflows */ + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0, + "RCU dynticks_nesting counter underflow!"); + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0, + "RCU dynticks_nmi_nesting counter underflow/zero!"); + + /* Are we at first interrupt nesting level? */ + if (__this_cpu_read(rcu_data.dynticks_nmi_nesting) != 1) + return false; + + /* Does CPU appear to be idle from an RCU standpoint? */ + return __this_cpu_read(rcu_data.dynticks_nesting) == 0; } -#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch. */ +#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch ... */ +#define DEFAULT_MAX_RCU_BLIMIT 10000 /* ... even during callback flood. */ static long blimit = DEFAULT_RCU_BLIMIT; #define DEFAULT_RCU_QHIMARK 10000 /* If this many pending, ignore blimit. */ static long qhimark = DEFAULT_RCU_QHIMARK; @@ -2113,7 +2135,7 @@ static void rcu_do_batch(struct rcu_data *rdp) /* Reinstate batch limit if we have worked down the excess. */ count = rcu_segcblist_n_cbs(&rdp->cblist); - if (rdp->blimit == LONG_MAX && count <= qlowmark) + if (rdp->blimit >= DEFAULT_MAX_RCU_BLIMIT && count <= qlowmark) rdp->blimit = blimit; /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ @@ -2253,7 +2275,7 @@ void rcu_force_quiescent_state(void) EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); /* Perform RCU core processing work for the current CPU. */ -static __latent_entropy void rcu_core(struct softirq_action *unused) +static __latent_entropy void rcu_core(void) { unsigned long flags; struct rcu_data *rdp = raw_cpu_ptr(&rcu_data); @@ -2287,37 +2309,126 @@ static __latent_entropy void rcu_core(struct softirq_action *unused) rcu_check_gp_start_stall(rnp, rdp, rcu_jiffies_till_stall_check()); /* If there are callbacks ready, invoke them. */ - if (rcu_segcblist_ready_cbs(&rdp->cblist)) - invoke_rcu_callbacks(rdp); + if (rcu_segcblist_ready_cbs(&rdp->cblist) && + likely(READ_ONCE(rcu_scheduler_fully_active))) + rcu_do_batch(rdp); /* Do any needed deferred wakeups of rcuo kthreads. */ do_nocb_deferred_wakeup(rdp); trace_rcu_utilization(TPS("End RCU core")); } +static void rcu_core_si(struct softirq_action *h) +{ + rcu_core(); +} + +static void rcu_wake_cond(struct task_struct *t, int status) +{ + /* + * If the thread is yielding, only wake it when this + * is invoked from idle + */ + if (t && (status != RCU_KTHREAD_YIELDING || is_idle_task(current))) + wake_up_process(t); +} + +static void invoke_rcu_core_kthread(void) +{ + struct task_struct *t; + unsigned long flags; + + local_irq_save(flags); + __this_cpu_write(rcu_data.rcu_cpu_has_work, 1); + t = __this_cpu_read(rcu_data.rcu_cpu_kthread_task); + if (t != NULL && t != current) + rcu_wake_cond(t, __this_cpu_read(rcu_data.rcu_cpu_kthread_status)); + local_irq_restore(flags); +} + /* - * Schedule RCU callback invocation. If the running implementation of RCU - * does not support RCU priority boosting, just do a direct call, otherwise - * wake up the per-CPU kernel kthread. Note that because we are running - * on the current CPU with softirqs disabled, the rcu_cpu_kthread_task - * cannot disappear out from under us. + * Wake up this CPU's rcuc kthread to do RCU core processing. */ -static void invoke_rcu_callbacks(struct rcu_data *rdp) +static void invoke_rcu_core(void) { - if (unlikely(!READ_ONCE(rcu_scheduler_fully_active))) - return; - if (likely(!rcu_state.boost)) { - rcu_do_batch(rdp); + if (!cpu_online(smp_processor_id())) return; + if (use_softirq) + raise_softirq(RCU_SOFTIRQ); + else + invoke_rcu_core_kthread(); +} + +static void rcu_cpu_kthread_park(unsigned int cpu) +{ + per_cpu(rcu_data.rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU; +} + +static int rcu_cpu_kthread_should_run(unsigned int cpu) +{ + return __this_cpu_read(rcu_data.rcu_cpu_has_work); +} + +/* + * Per-CPU kernel thread that invokes RCU callbacks. This replaces + * the RCU softirq used in configurations of RCU that do not support RCU + * priority boosting. + */ +static void rcu_cpu_kthread(unsigned int cpu) +{ + unsigned int *statusp = this_cpu_ptr(&rcu_data.rcu_cpu_kthread_status); + char work, *workp = this_cpu_ptr(&rcu_data.rcu_cpu_has_work); + int spincnt; + + for (spincnt = 0; spincnt < 10; spincnt++) { + trace_rcu_utilization(TPS("Start CPU kthread@rcu_wait")); + local_bh_disable(); + *statusp = RCU_KTHREAD_RUNNING; + local_irq_disable(); + work = *workp; + *workp = 0; + local_irq_enable(); + if (work) + rcu_core(); + local_bh_enable(); + if (*workp == 0) { + trace_rcu_utilization(TPS("End CPU kthread@rcu_wait")); + *statusp = RCU_KTHREAD_WAITING; + return; + } } - invoke_rcu_callbacks_kthread(); + *statusp = RCU_KTHREAD_YIELDING; + trace_rcu_utilization(TPS("Start CPU kthread@rcu_yield")); + schedule_timeout_interruptible(2); + trace_rcu_utilization(TPS("End CPU kthread@rcu_yield")); + *statusp = RCU_KTHREAD_WAITING; } -static void invoke_rcu_core(void) +static struct smp_hotplug_thread rcu_cpu_thread_spec = { + .store = &rcu_data.rcu_cpu_kthread_task, + .thread_should_run = rcu_cpu_kthread_should_run, + .thread_fn = rcu_cpu_kthread, + .thread_comm = "rcuc/%u", + .setup = rcu_cpu_kthread_setup, + .park = rcu_cpu_kthread_park, +}; + +/* + * Spawn per-CPU RCU core processing kthreads. + */ +static int __init rcu_spawn_core_kthreads(void) { - if (cpu_online(smp_processor_id())) - raise_softirq(RCU_SOFTIRQ); + int cpu; + + for_each_possible_cpu(cpu) + per_cpu(rcu_data.rcu_cpu_has_work, cpu) = 0; + if (!IS_ENABLED(CONFIG_RCU_BOOST) && use_softirq) + return 0; + WARN_ONCE(smpboot_register_percpu_thread(&rcu_cpu_thread_spec), + "%s: Could not start rcuc kthread, OOM is now expected behavior\n", __func__); + return 0; } +early_initcall(rcu_spawn_core_kthreads); /* * Handle any core-RCU processing required by a call_rcu() invocation. @@ -2354,7 +2465,7 @@ static void __call_rcu_core(struct rcu_data *rdp, struct rcu_head *head, rcu_accelerate_cbs_unlocked(rdp->mynode, rdp); } else { /* Give the grace period a kick. */ - rdp->blimit = LONG_MAX; + rdp->blimit = DEFAULT_MAX_RCU_BLIMIT; if (rcu_state.n_force_qs == rdp->n_force_qs_snap && rcu_segcblist_first_pend_cb(&rdp->cblist) != head) rcu_force_quiescent_state(); @@ -3355,7 +3466,8 @@ void __init rcu_init(void) rcu_init_one(); if (dump_tree) rcu_dump_rcu_node_tree(); - open_softirq(RCU_SOFTIRQ, rcu_core); + if (use_softirq) + open_softirq(RCU_SOFTIRQ, rcu_core_si); /* * We don't need protection against CPU-hotplug here because diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index e253d11af3c4..7acaf3a62d39 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -154,13 +154,15 @@ struct rcu_data { bool core_needs_qs; /* Core waits for quiesc state. */ bool beenonline; /* CPU online at least once. */ bool gpwrap; /* Possible ->gp_seq wrap. */ - bool deferred_qs; /* This CPU awaiting a deferred QS? */ + bool exp_deferred_qs; /* This CPU awaiting a deferred QS? */ struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ unsigned long grpmask; /* Mask to apply to leaf qsmask. */ unsigned long ticks_this_gp; /* The number of scheduling-clock */ /* ticks this CPU has handled */ /* during and after the last grace */ /* period it is aware of. */ + struct irq_work defer_qs_iw; /* Obtain later scheduler attention. */ + bool defer_qs_iw_pending; /* Scheduler attention pending? */ /* 2) batch handling */ struct rcu_segcblist cblist; /* Segmented callback list, with */ @@ -407,8 +409,8 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func); static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck); static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); -static void invoke_rcu_callbacks_kthread(void); static bool rcu_is_callbacks_kthread(void); +static void rcu_cpu_kthread_setup(unsigned int cpu); static void __init rcu_spawn_boost_kthreads(void); static void rcu_prepare_kthreads(int cpu); static void rcu_cleanup_after_idle(void); diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 9c990df880d1..af7e7b9c86af 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -250,7 +250,7 @@ static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, */ static void rcu_report_exp_rdp(struct rcu_data *rdp) { - WRITE_ONCE(rdp->deferred_qs, false); + WRITE_ONCE(rdp->exp_deferred_qs, false); rcu_report_exp_cpu_mult(rdp->mynode, rdp->grpmask, true); } @@ -259,8 +259,7 @@ static bool sync_exp_work_done(unsigned long s) { if (rcu_exp_gp_seq_done(s)) { trace_rcu_exp_grace_period(rcu_state.name, s, TPS("done")); - /* Ensure test happens before caller kfree(). */ - smp_mb__before_atomic(); /* ^^^ */ + smp_mb(); /* Ensure test happens before caller kfree(). */ return true; } return false; @@ -384,7 +383,12 @@ retry_ipi: mask_ofl_test |= mask; continue; } + if (get_cpu() == cpu) { + put_cpu(); + continue; + } ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0); + put_cpu(); if (!ret) { mask_ofl_ipi &= ~mask; continue; @@ -611,7 +615,7 @@ static void rcu_exp_handler(void *unused) rcu_dynticks_curr_cpu_in_eqs()) { rcu_report_exp_rdp(rdp); } else { - rdp->deferred_qs = true; + rdp->exp_deferred_qs = true; set_tsk_need_resched(t); set_preempt_need_resched(); } @@ -633,7 +637,7 @@ static void rcu_exp_handler(void *unused) if (t->rcu_read_lock_nesting > 0) { raw_spin_lock_irqsave_rcu_node(rnp, flags); if (rnp->expmask & rdp->grpmask) { - rdp->deferred_qs = true; + rdp->exp_deferred_qs = true; t->rcu_read_unlock_special.b.exp_hint = true; } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -656,7 +660,7 @@ static void rcu_exp_handler(void *unused) * * Otherwise, force a context switch after the CPU enables everything. */ - rdp->deferred_qs = true; + rdp->exp_deferred_qs = true; if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) || WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs())) { rcu_preempt_deferred_qs(t); @@ -694,6 +698,16 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp) #else /* #ifdef CONFIG_PREEMPT_RCU */ +/* Request an expedited quiescent state. */ +static void rcu_exp_need_qs(void) +{ + __this_cpu_write(rcu_data.cpu_no_qs.b.exp, true); + /* Store .exp before .rcu_urgent_qs. */ + smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true); + set_tsk_need_resched(current); + set_preempt_need_resched(); +} + /* Invoked on each online non-idle CPU for expedited quiescent state. */ static void rcu_exp_handler(void *unused) { @@ -709,25 +723,38 @@ static void rcu_exp_handler(void *unused) rcu_report_exp_rdp(this_cpu_ptr(&rcu_data)); return; } - __this_cpu_write(rcu_data.cpu_no_qs.b.exp, true); - /* Store .exp before .rcu_urgent_qs. */ - smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true); - set_tsk_need_resched(current); - set_preempt_need_resched(); + rcu_exp_need_qs(); } /* Send IPI for expedited cleanup if needed at end of CPU-hotplug operation. */ static void sync_sched_exp_online_cleanup(int cpu) { + unsigned long flags; + int my_cpu; struct rcu_data *rdp; int ret; struct rcu_node *rnp; rdp = per_cpu_ptr(&rcu_data, cpu); rnp = rdp->mynode; - if (!(READ_ONCE(rnp->expmask) & rdp->grpmask)) + my_cpu = get_cpu(); + /* Quiescent state either not needed or already requested, leave. */ + if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) || + __this_cpu_read(rcu_data.cpu_no_qs.b.exp)) { + put_cpu(); + return; + } + /* Quiescent state needed on current CPU, so set it up locally. */ + if (my_cpu == cpu) { + local_irq_save(flags); + rcu_exp_need_qs(); + local_irq_restore(flags); + put_cpu(); return; + } + /* Quiescent state needed on some other CPU, send IPI. */ ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0); + put_cpu(); WARN_ON_ONCE(ret); } @@ -765,7 +792,6 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp) */ void synchronize_rcu_expedited(void) { - struct rcu_data *rdp; struct rcu_exp_work rew; struct rcu_node *rnp; unsigned long s; @@ -802,7 +828,6 @@ void synchronize_rcu_expedited(void) } /* Wait for expedited grace period to complete. */ - rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id()); rnp = rcu_get_root(); wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3], sync_exp_work_done(s)); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 1102765f91fd..acb225023ed1 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -11,29 +11,7 @@ * Paul E. McKenney <paulmck@linux.ibm.com> */ -#include <linux/delay.h> -#include <linux/gfp.h> -#include <linux/oom.h> -#include <linux/sched/debug.h> -#include <linux/smpboot.h> -#include <linux/sched/isolation.h> -#include <uapi/linux/sched/types.h> -#include "../time/tick-internal.h" - -#ifdef CONFIG_RCU_BOOST #include "../locking/rtmutex_common.h" -#else /* #ifdef CONFIG_RCU_BOOST */ - -/* - * Some architectures do not define rt_mutexes, but if !CONFIG_RCU_BOOST, - * all uses are in dead code. Provide a definition to keep the compiler - * happy, but add WARN_ON_ONCE() to complain if used in the wrong place. - * This probably needs to be excluded from -rt builds. - */ -#define rt_mutex_owner(a) ({ WARN_ON_ONCE(1); NULL; }) -#define rt_mutex_futex_unlock(x) WARN_ON_ONCE(1) - -#endif /* #else #ifdef CONFIG_RCU_BOOST */ #ifdef CONFIG_RCU_NOCB_CPU static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */ @@ -94,6 +72,8 @@ static void __init rcu_bootup_announce_oddness(void) pr_info("\tRCU debug GP init slowdown %d jiffies.\n", gp_init_delay); if (gp_cleanup_delay) pr_info("\tRCU debug GP init slowdown %d jiffies.\n", gp_cleanup_delay); + if (!use_softirq) + pr_info("\tRCU_SOFTIRQ processing moved to rcuc kthreads.\n"); if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG)) pr_info("\tRCU debug extended QS entry/exit.\n"); rcupdate_announce_bootup_oddness(); @@ -257,10 +237,10 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) * no need to check for a subsequent expedited GP. (Though we are * still in a quiescent state in any case.) */ - if (blkd_state & RCU_EXP_BLKD && rdp->deferred_qs) + if (blkd_state & RCU_EXP_BLKD && rdp->exp_deferred_qs) rcu_report_exp_rdp(rdp); else - WARN_ON_ONCE(rdp->deferred_qs); + WARN_ON_ONCE(rdp->exp_deferred_qs); } /* @@ -357,7 +337,7 @@ void rcu_note_context_switch(bool preempt) * means that we continue to block the current grace period. */ rcu_qs(); - if (rdp->deferred_qs) + if (rdp->exp_deferred_qs) rcu_report_exp_rdp(rdp); trace_rcu_utilization(TPS("End context switch")); barrier(); /* Avoid RCU read-side critical sections leaking up. */ @@ -471,14 +451,15 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) */ special = t->rcu_read_unlock_special; rdp = this_cpu_ptr(&rcu_data); - if (!special.s && !rdp->deferred_qs) { + if (!special.s && !rdp->exp_deferred_qs) { local_irq_restore(flags); return; } + t->rcu_read_unlock_special.b.deferred_qs = false; if (special.b.need_qs) { rcu_qs(); t->rcu_read_unlock_special.b.need_qs = false; - if (!t->rcu_read_unlock_special.s && !rdp->deferred_qs) { + if (!t->rcu_read_unlock_special.s && !rdp->exp_deferred_qs) { local_irq_restore(flags); return; } @@ -490,7 +471,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) * tasks are handled when removing the task from the * blocked-tasks list below. */ - if (rdp->deferred_qs) { + if (rdp->exp_deferred_qs) { rcu_report_exp_rdp(rdp); if (!t->rcu_read_unlock_special.s) { local_irq_restore(flags); @@ -579,7 +560,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) */ static bool rcu_preempt_need_deferred_qs(struct task_struct *t) { - return (__this_cpu_read(rcu_data.deferred_qs) || + return (__this_cpu_read(rcu_data.exp_deferred_qs) || READ_ONCE(t->rcu_read_unlock_special.s)) && t->rcu_read_lock_nesting <= 0; } @@ -607,6 +588,17 @@ static void rcu_preempt_deferred_qs(struct task_struct *t) } /* + * Minimal handler to give the scheduler a chance to re-evaluate. + */ +static void rcu_preempt_deferred_qs_handler(struct irq_work *iwp) +{ + struct rcu_data *rdp; + + rdp = container_of(iwp, struct rcu_data, defer_qs_iw); + rdp->defer_qs_iw_pending = false; +} + +/* * Handle special cases during rcu_read_unlock(), such as needing to * notify RCU core processing or task having blocked during the RCU * read-side critical section. @@ -625,16 +617,41 @@ static void rcu_read_unlock_special(struct task_struct *t) local_irq_save(flags); irqs_were_disabled = irqs_disabled_flags(flags); if (preempt_bh_were_disabled || irqs_were_disabled) { - WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, false); - /* Need to defer quiescent state until everything is enabled. */ - if (irqs_were_disabled) { - /* Enabling irqs does not reschedule, so... */ + bool exp; + struct rcu_data *rdp = this_cpu_ptr(&rcu_data); + struct rcu_node *rnp = rdp->mynode; + + t->rcu_read_unlock_special.b.exp_hint = false; + exp = (t->rcu_blocked_node && t->rcu_blocked_node->exp_tasks) || + (rdp->grpmask & rnp->expmask) || + tick_nohz_full_cpu(rdp->cpu); + // Need to defer quiescent state until everything is enabled. + if ((exp || in_irq()) && irqs_were_disabled && use_softirq && + (in_irq() || !t->rcu_read_unlock_special.b.deferred_qs)) { + // Using softirq, safe to awaken, and we get + // no help from enabling irqs, unlike bh/preempt. raise_softirq_irqoff(RCU_SOFTIRQ); + } else if (exp && irqs_were_disabled && !use_softirq && + !t->rcu_read_unlock_special.b.deferred_qs) { + // Safe to awaken and we get no help from enabling + // irqs, unlike bh/preempt. + invoke_rcu_core(); } else { - /* Enabling BH or preempt does reschedule, so... */ + // Enabling BH or preempt does reschedule, so... + // Also if no expediting or NO_HZ_FULL, slow is OK. set_tsk_need_resched(current); set_preempt_need_resched(); + if (IS_ENABLED(CONFIG_IRQ_WORK) && + !rdp->defer_qs_iw_pending && exp) { + // Get scheduler to re-evaluate and call hooks. + // If !IRQ_WORK, FQS scan will eventually IPI. + init_irq_work(&rdp->defer_qs_iw, + rcu_preempt_deferred_qs_handler); + rdp->defer_qs_iw_pending = true; + irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu); + } } + t->rcu_read_unlock_special.b.deferred_qs = true; local_irq_restore(flags); return; } @@ -760,7 +777,7 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck) i = 0; list_for_each(lhp, &rnp->blkd_tasks) { pr_cont(" %p", lhp); - if (++i >= 10) + if (++i >= ncheck) break; } pr_cont("\n"); @@ -944,18 +961,21 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck) #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ +/* + * If boosting, set rcuc kthreads to realtime priority. + */ +static void rcu_cpu_kthread_setup(unsigned int cpu) +{ #ifdef CONFIG_RCU_BOOST + struct sched_param sp; -static void rcu_wake_cond(struct task_struct *t, int status) -{ - /* - * If the thread is yielding, only wake it when this - * is invoked from idle - */ - if (status != RCU_KTHREAD_YIELDING || is_idle_task(current)) - wake_up_process(t); + sp.sched_priority = kthread_prio; + sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); +#endif /* #ifdef CONFIG_RCU_BOOST */ } +#ifdef CONFIG_RCU_BOOST + /* * Carry out RCU priority boosting on the task indicated by ->exp_tasks * or ->boost_tasks, advancing the pointer to the next task in the @@ -1091,23 +1111,6 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) } /* - * Wake up the per-CPU kthread to invoke RCU callbacks. - */ -static void invoke_rcu_callbacks_kthread(void) -{ - unsigned long flags; - - local_irq_save(flags); - __this_cpu_write(rcu_data.rcu_cpu_has_work, 1); - if (__this_cpu_read(rcu_data.rcu_cpu_kthread_task) != NULL && - current != __this_cpu_read(rcu_data.rcu_cpu_kthread_task)) { - rcu_wake_cond(__this_cpu_read(rcu_data.rcu_cpu_kthread_task), - __this_cpu_read(rcu_data.rcu_cpu_kthread_status)); - } - local_irq_restore(flags); -} - -/* * Is the current CPU running the RCU-callbacks kthread? * Caller must have preemption disabled. */ @@ -1160,59 +1163,6 @@ static int rcu_spawn_one_boost_kthread(struct rcu_node *rnp) return 0; } -static void rcu_cpu_kthread_setup(unsigned int cpu) -{ - struct sched_param sp; - - sp.sched_priority = kthread_prio; - sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); -} - -static void rcu_cpu_kthread_park(unsigned int cpu) -{ - per_cpu(rcu_data.rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU; -} - -static int rcu_cpu_kthread_should_run(unsigned int cpu) -{ - return __this_cpu_read(rcu_data.rcu_cpu_has_work); -} - -/* - * Per-CPU kernel thread that invokes RCU callbacks. This replaces - * the RCU softirq used in configurations of RCU that do not support RCU - * priority boosting. - */ -static void rcu_cpu_kthread(unsigned int cpu) -{ - unsigned int *statusp = this_cpu_ptr(&rcu_data.rcu_cpu_kthread_status); - char work, *workp = this_cpu_ptr(&rcu_data.rcu_cpu_has_work); - int spincnt; - - for (spincnt = 0; spincnt < 10; spincnt++) { - trace_rcu_utilization(TPS("Start CPU kthread@rcu_wait")); - local_bh_disable(); - *statusp = RCU_KTHREAD_RUNNING; - local_irq_disable(); - work = *workp; - *workp = 0; - local_irq_enable(); - if (work) - rcu_do_batch(this_cpu_ptr(&rcu_data)); - local_bh_enable(); - if (*workp == 0) { - trace_rcu_utilization(TPS("End CPU kthread@rcu_wait")); - *statusp = RCU_KTHREAD_WAITING; - return; - } - } - *statusp = RCU_KTHREAD_YIELDING; - trace_rcu_utilization(TPS("Start CPU kthread@rcu_yield")); - schedule_timeout_interruptible(2); - trace_rcu_utilization(TPS("End CPU kthread@rcu_yield")); - *statusp = RCU_KTHREAD_WAITING; -} - /* * Set the per-rcu_node kthread's affinity to cover all CPUs that are * served by the rcu_node in question. The CPU hotplug lock is still @@ -1243,27 +1193,13 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) free_cpumask_var(cm); } -static struct smp_hotplug_thread rcu_cpu_thread_spec = { - .store = &rcu_data.rcu_cpu_kthread_task, - .thread_should_run = rcu_cpu_kthread_should_run, - .thread_fn = rcu_cpu_kthread, - .thread_comm = "rcuc/%u", - .setup = rcu_cpu_kthread_setup, - .park = rcu_cpu_kthread_park, -}; - /* * Spawn boost kthreads -- called as soon as the scheduler is running. */ static void __init rcu_spawn_boost_kthreads(void) { struct rcu_node *rnp; - int cpu; - for_each_possible_cpu(cpu) - per_cpu(rcu_data.rcu_cpu_has_work, cpu) = 0; - if (WARN_ONCE(smpboot_register_percpu_thread(&rcu_cpu_thread_spec), "%s: Could not start rcub kthread, OOM is now expected behavior\n", __func__)) - return; rcu_for_each_leaf_node(rnp) (void)rcu_spawn_one_boost_kthread(rnp); } @@ -1286,11 +1222,6 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } -static void invoke_rcu_callbacks_kthread(void) -{ - WARN_ON_ONCE(1); -} - static bool rcu_is_callbacks_kthread(void) { return false; diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index f65a73a97323..065183391f75 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -630,7 +630,9 @@ static void rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp, time_before(j, rcu_state.gp_req_activity + gpssdelay) || time_before(j, rcu_state.gp_activity + gpssdelay) || atomic_xchg(&warned, 1)) { - raw_spin_unlock_rcu_node(rnp_root); /* irqs remain disabled. */ + if (rnp_root != rnp) + /* irqs remain disabled. */ + raw_spin_unlock_rcu_node(rnp_root); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); return; } diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index c3bf44ba42e5..61df2bf08563 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -423,6 +423,19 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); do { } while (0) #endif +#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) +/* Get rcutorture access to sched_setaffinity(). */ +long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask) +{ + int ret; + + ret = sched_setaffinity(pid, in_mask); + WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret); + return ret; +} +EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity); +#endif + #ifdef CONFIG_RCU_STALL_COMMON int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); diff --git a/kernel/torture.c b/kernel/torture.c index 17b2be9bde12..a8d9bdfba7c3 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -570,6 +570,7 @@ static void torture_shutdown_cleanup(void) static struct task_struct *stutter_task; static int stutter_pause_test; static int stutter; +static int stutter_gap; /* * Block until the stutter interval ends. This must be called periodically @@ -578,10 +579,12 @@ static int stutter; bool stutter_wait(const char *title) { int spt; + bool ret = false; cond_resched_tasks_rcu_qs(); spt = READ_ONCE(stutter_pause_test); for (; spt; spt = READ_ONCE(stutter_pause_test)) { + ret = true; if (spt == 1) { schedule_timeout_interruptible(1); } else if (spt == 2) { @@ -592,7 +595,7 @@ bool stutter_wait(const char *title) } torture_shutdown_absorb(title); } - return !!spt; + return ret; } EXPORT_SYMBOL_GPL(stutter_wait); @@ -602,17 +605,24 @@ EXPORT_SYMBOL_GPL(stutter_wait); */ static int torture_stutter(void *arg) { + int wtime; + VERBOSE_TOROUT_STRING("torture_stutter task started"); do { if (!torture_must_stop() && stutter > 1) { - WRITE_ONCE(stutter_pause_test, 1); - schedule_timeout_interruptible(stutter - 1); + wtime = stutter; + if (stutter > HZ + 1) { + WRITE_ONCE(stutter_pause_test, 1); + wtime = stutter - HZ - 1; + schedule_timeout_interruptible(wtime); + wtime = HZ + 1; + } WRITE_ONCE(stutter_pause_test, 2); - schedule_timeout_interruptible(1); + schedule_timeout_interruptible(wtime); } WRITE_ONCE(stutter_pause_test, 0); if (!torture_must_stop()) - schedule_timeout_interruptible(stutter); + schedule_timeout_interruptible(stutter_gap); torture_shutdown_absorb("torture_stutter"); } while (!torture_must_stop()); torture_kthread_stopping("torture_stutter"); @@ -622,9 +632,10 @@ static int torture_stutter(void *arg) /* * Initialize and kick off the torture_stutter kthread. */ -int torture_stutter_init(const int s) +int torture_stutter_init(const int s, const int sgap) { stutter = s; + stutter_gap = sgap; return torture_create_kthread(torture_stutter, NULL, stutter_task); } EXPORT_SYMBOL_GPL(torture_stutter_init); diff --git a/tools/include/linux/rcu.h b/tools/include/linux/rcu.h index 7d02527e5bce..9554d3fa54f3 100644 --- a/tools/include/linux/rcu.h +++ b/tools/include/linux/rcu.h @@ -19,7 +19,7 @@ static inline bool rcu_is_watching(void) return false; } -#define rcu_assign_pointer(p, v) ((p) = (v)) -#define RCU_INIT_POINTER(p, v) p=(v) +#define rcu_assign_pointer(p, v) do { (p) = (v); } while (0) +#define RCU_INIT_POINTER(p, v) do { (p) = (v); } while (0) #endif diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell index def9131d3d8e..5be86b1025e8 100644 --- a/tools/memory-model/linux-kernel.bell +++ b/tools/memory-model/linux-kernel.bell @@ -24,6 +24,7 @@ instructions RMW[{'once,'acquire,'release}] enum Barriers = 'wmb (*smp_wmb*) || 'rmb (*smp_rmb*) || 'mb (*smp_mb*) || + 'barrier (*barrier*) || 'rcu-lock (*rcu_read_lock*) || 'rcu-unlock (*rcu_read_unlock*) || 'sync-rcu (*synchronize_rcu*) || @@ -76,3 +77,8 @@ flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep (* Validate SRCU dynamic match *) flag ~empty different-values(srcu-rscs) as srcu-bad-nesting + +(* Compute marked and plain memory accesses *) +let Marked = (~M) | IW | Once | Release | Acquire | domain(rmw) | range(rmw) | + LKR | LKW | UL | LF | RL | RU +let Plain = M \ Marked diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index 8dcb37835b61..ea2ff4b94074 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -24,8 +24,14 @@ include "lock.cat" (* Basic relations *) (*******************) +(* Release Acquire *) +let acq-po = [Acquire] ; po ; [M] +let po-rel = [M] ; po ; [Release] +let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po + (* Fences *) -let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn] +let R4rmb = R \ Noreturn (* Reads for which rmb works *) +let rmb = [R4rmb] ; fencerel(Rmb) ; [R4rmb] let wmb = [W] ; fencerel(Wmb) ; [W] let mb = ([M] ; fencerel(Mb) ; [M]) | ([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) | @@ -34,13 +40,14 @@ let mb = ([M] ; fencerel(Mb) ; [M]) | ([M] ; po ; [UL] ; (co | po) ; [LKW] ; fencerel(After-unlock-lock) ; [M]) let gp = po ; [Sync-rcu | Sync-srcu] ; po? - let strong-fence = mb | gp -(* Release Acquire *) -let acq-po = [Acquire] ; po ; [M] -let po-rel = [M] ; po ; [Release] -let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po +let nonrw-fence = strong-fence | po-rel | acq-po +let fence = nonrw-fence | wmb | rmb +let barrier = fencerel(Barrier | Rmb | Wmb | Mb | Sync-rcu | Sync-srcu | + Before-atomic | After-atomic | Acquire | Release | + Rcu-lock | Rcu-unlock | Srcu-lock | Srcu-unlock) | + (po ; [Release]) | ([Acquire] ; po) (**********************************) (* Fundamental coherence ordering *) @@ -61,21 +68,22 @@ empty rmw & (fre ; coe) as atomic let dep = addr | data let rwdep = (dep | ctrl) ; [W] let overwrite = co | fr -let to-w = rwdep | (overwrite & int) -let to-r = addr | (dep ; rfi) -let fence = strong-fence | wmb | po-rel | rmb | acq-po +let to-w = rwdep | (overwrite & int) | (addr ; [Plain] ; wmb) +let to-r = addr | (dep ; [Marked] ; rfi) let ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int) (* Propagation: Ordering from release operations and strong fences. *) -let A-cumul(r) = rfe? ; r -let cumul-fence = A-cumul(strong-fence | po-rel) | wmb | po-unlock-rf-lock-po -let prop = (overwrite & ext)? ; cumul-fence* ; rfe? +let A-cumul(r) = (rfe ; [Marked])? ; r +let cumul-fence = [Marked] ; (A-cumul(strong-fence | po-rel) | wmb | + po-unlock-rf-lock-po) ; [Marked] +let prop = [Marked] ; (overwrite & ext)? ; cumul-fence* ; + [Marked] ; rfe? ; [Marked] (* * Happens Before: Ordering from the passage of time. * No fences needed here for prop because relation confined to one process. *) -let hb = ppo | rfe | ((prop \ id) & int) +let hb = [Marked] ; (ppo | rfe | ((prop \ id) & int)) ; [Marked] acyclic hb as happens-before (****************************************) @@ -83,7 +91,7 @@ acyclic hb as happens-before (****************************************) (* Propagation: Each non-rf link needs a strong fence. *) -let pb = prop ; strong-fence ; hb* +let pb = prop ; strong-fence ; hb* ; [Marked] acyclic pb as propagation (*******) @@ -114,24 +122,28 @@ let rcu-link = po? ; hb* ; pb* ; prop ; po (* * Any sequence containing at least as many grace periods as RCU read-side - * critical sections (joined by rcu-link) acts as a generalized strong fence. + * critical sections (joined by rcu-link) induces order like a generalized + * inter-CPU strong fence. * Likewise for SRCU grace periods and read-side critical sections, provided * the synchronize_srcu() and srcu_read_[un]lock() calls refer to the same * struct srcu_struct location. *) -let rec rcu-fence = rcu-gp | srcu-gp | +let rec rcu-order = rcu-gp | srcu-gp | (rcu-gp ; rcu-link ; rcu-rscsi) | ((srcu-gp ; rcu-link ; srcu-rscsi) & loc) | (rcu-rscsi ; rcu-link ; rcu-gp) | ((srcu-rscsi ; rcu-link ; srcu-gp) & loc) | - (rcu-gp ; rcu-link ; rcu-fence ; rcu-link ; rcu-rscsi) | - ((srcu-gp ; rcu-link ; rcu-fence ; rcu-link ; srcu-rscsi) & loc) | - (rcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; rcu-gp) | - ((srcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; srcu-gp) & loc) | - (rcu-fence ; rcu-link ; rcu-fence) + (rcu-gp ; rcu-link ; rcu-order ; rcu-link ; rcu-rscsi) | + ((srcu-gp ; rcu-link ; rcu-order ; rcu-link ; srcu-rscsi) & loc) | + (rcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; rcu-gp) | + ((srcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; srcu-gp) & loc) | + (rcu-order ; rcu-link ; rcu-order) +let rcu-fence = po ; rcu-order ; po? +let fence = fence | rcu-fence +let strong-fence = strong-fence | rcu-fence (* rb orders instructions just as pb does *) -let rb = prop ; po ; rcu-fence ; po? ; hb* ; pb* +let rb = prop ; rcu-fence ; hb* ; pb* ; [Marked] irreflexive rb as rcu @@ -143,3 +155,49 @@ irreflexive rb as rcu * let xb = hb | pb | rb * acyclic xb as executes-before *) + +(*********************************) +(* Plain accesses and data races *) +(*********************************) + +(* Warn about plain writes and marked accesses in the same region *) +let mixed-accesses = ([Plain & W] ; (po-loc \ barrier) ; [Marked]) | + ([Marked] ; (po-loc \ barrier) ; [Plain & W]) +flag ~empty mixed-accesses as mixed-accesses + +(* Executes-before and visibility *) +let xbstar = (hb | pb | rb)* +let vis = cumul-fence* ; rfe? ; [Marked] ; + ((strong-fence ; [Marked] ; xbstar) | (xbstar & int)) + +(* Boundaries for lifetimes of plain accesses *) +let w-pre-bounded = [Marked] ; (addr | fence)? +let r-pre-bounded = [Marked] ; (addr | nonrw-fence | + ([R4rmb] ; fencerel(Rmb) ; [~Noreturn]))? +let w-post-bounded = fence? ; [Marked] +let r-post-bounded = (nonrw-fence | ([~Noreturn] ; fencerel(Rmb) ; [R4rmb]))? ; + [Marked] + +(* Visibility and executes-before for plain accesses *) +let ww-vis = fence | (strong-fence ; xbstar ; w-pre-bounded) | + (w-post-bounded ; vis ; w-pre-bounded) +let wr-vis = fence | (strong-fence ; xbstar ; r-pre-bounded) | + (w-post-bounded ; vis ; r-pre-bounded) +let rw-xbstar = fence | (r-post-bounded ; xbstar ; w-pre-bounded) + +(* Potential races *) +let pre-race = ext & ((Plain * M) | ((M \ IW) * Plain)) + +(* Coherence requirements for plain accesses *) +let wr-incoh = pre-race & rf & rw-xbstar^-1 +let rw-incoh = pre-race & fr & wr-vis^-1 +let ww-incoh = pre-race & co & ww-vis^-1 +empty (wr-incoh | rw-incoh | ww-incoh) as plain-coherence + +(* Actual races *) +let ww-nonrace = ww-vis & ((Marked * W) | rw-xbstar) & ((W * Marked) | wr-vis) +let ww-race = (pre-race & co) \ ww-nonrace +let wr-race = (pre-race & (co? ; rf)) \ wr-vis +let rw-race = (pre-race & fr) \ rw-xbstar + +flag ~empty (ww-race | wr-race | rw-race) as data-race diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def index 551eeaa389d4..ef0f3c1850de 100644 --- a/tools/memory-model/linux-kernel.def +++ b/tools/memory-model/linux-kernel.def @@ -24,6 +24,7 @@ smp_mb__before_atomic() { __fence{before-atomic}; } smp_mb__after_atomic() { __fence{after-atomic}; } smp_mb__after_spinlock() { __fence{after-spinlock}; } smp_mb__after_unlock_lock() { __fence{after-unlock-lock}; } +barrier() { __fence{barrier}; } // Exchange xchg(X,V) __xchg{mb}(X,V) diff --git a/tools/memory-model/litmus-tests/MP+poonceonces.litmus b/tools/memory-model/litmus-tests/MP+poonceonces.litmus index b2b60b84fb9d..172f0145301c 100644 --- a/tools/memory-model/litmus-tests/MP+poonceonces.litmus +++ b/tools/memory-model/litmus-tests/MP+poonceonces.litmus @@ -1,7 +1,7 @@ C MP+poonceonces (* - * Result: Maybe + * Result: Sometimes * * Can the counter-intuitive message-passing outcome be prevented with * no ordering at all? diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README index 5ee08f129094..681f9067fa9e 100644 --- a/tools/memory-model/litmus-tests/README +++ b/tools/memory-model/litmus-tests/README @@ -244,7 +244,7 @@ produce the name: Adding the ".litmus" suffix: SB+rfionceonce-poonceonces.litmus The descriptors that describe connections between consecutive accesses -within the cycle through a given litmus test can be provided by the herd +within the cycle through a given litmus test can be provided by the herd7 tool (Rfi, Po, Fre, and so on) or by the linux-kernel.bell file (Once, Release, Acquire, and so on). diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat index a059d1a6d8a2..6b52f365d73a 100644 --- a/tools/memory-model/lock.cat +++ b/tools/memory-model/lock.cat @@ -11,7 +11,7 @@ include "cross.cat" (* - * The lock-related events generated by herd are as follows: + * The lock-related events generated by herd7 are as follows: * * LKR Lock-Read: the read part of a spin_lock() or successful * spin_trylock() read-modify-write event pair diff --git a/tools/memory-model/scripts/README b/tools/memory-model/scripts/README index 29375a1fbbfa..095c7eb36f9f 100644 --- a/tools/memory-model/scripts/README +++ b/tools/memory-model/scripts/README @@ -22,7 +22,7 @@ checklitmushist.sh Run all litmus tests having .litmus.out files from previous initlitmushist.sh or newlitmushist.sh runs, comparing the - herd output to that of the original runs. + herd7 output to that of the original runs. checklitmus.sh @@ -43,7 +43,7 @@ initlitmushist.sh judgelitmus.sh - Given a .litmus file and its .litmus.out herd output, check the + Given a .litmus file and its .litmus.out herd7 output, check the .litmus.out file against the .litmus file's "Result:" comment to judge whether the test ran correctly. Not normally run manually, provided instead for use by other scripts. diff --git a/tools/memory-model/scripts/checkalllitmus.sh b/tools/memory-model/scripts/checkalllitmus.sh index b35fcd61ecf6..3c0c7fbbd223 100755 --- a/tools/memory-model/scripts/checkalllitmus.sh +++ b/tools/memory-model/scripts/checkalllitmus.sh @@ -1,7 +1,7 @@ #!/bin/sh # SPDX-License-Identifier: GPL-2.0+ # -# Run herd tests on all .litmus files in the litmus-tests directory +# Run herd7 tests on all .litmus files in the litmus-tests directory # and check each file's result against a "Result:" comment within that # litmus test. If the verification result does not match that specified # in the litmus test, this script prints an error message prefixed with diff --git a/tools/memory-model/scripts/checklitmus.sh b/tools/memory-model/scripts/checklitmus.sh index dd08801a30b0..11461ed40b5e 100755 --- a/tools/memory-model/scripts/checklitmus.sh +++ b/tools/memory-model/scripts/checklitmus.sh @@ -1,7 +1,7 @@ #!/bin/sh # SPDX-License-Identifier: GPL-2.0+ # -# Run a herd test and invokes judgelitmus.sh to check the result against +# Run a herd7 test and invokes judgelitmus.sh to check the result against # a "Result:" comment within the litmus test. It also outputs verification # results to a file whose name is that of the specified litmus test, but # with ".out" appended. diff --git a/tools/memory-model/scripts/parseargs.sh b/tools/memory-model/scripts/parseargs.sh index 859e1d581e05..40f52080fdbd 100644 --- a/tools/memory-model/scripts/parseargs.sh +++ b/tools/memory-model/scripts/parseargs.sh @@ -91,7 +91,7 @@ do shift ;; --herdopts|--herdopt) - checkarg --destdir "(herd options)" "$#" "$2" '.*' '^--' + checkarg --destdir "(herd7 options)" "$#" "$2" '.*' '^--' LKMM_HERD_OPTIONS="$2" shift ;; diff --git a/tools/memory-model/scripts/runlitmushist.sh b/tools/memory-model/scripts/runlitmushist.sh index e507f5f933d5..6ed376f495bb 100644 --- a/tools/memory-model/scripts/runlitmushist.sh +++ b/tools/memory-model/scripts/runlitmushist.sh @@ -79,7 +79,7 @@ then echo ' ---' Summary: 1>&2 grep '!!!' $T/*.sh.out 1>&2 nfail="`grep '!!!' $T/*.sh.out | wc -l`" - echo 'Number of failed herd runs (e.g., timeout): ' $nfail 1>&2 + echo 'Number of failed herd7 runs (e.g., timeout): ' $nfail 1>&2 exit 1 else echo All runs completed successfully. 1>&2 diff --git a/tools/testing/radix-tree/linux/rcupdate.h b/tools/testing/radix-tree/linux/rcupdate.h index fd280b070fdb..fed468fb0c78 100644 --- a/tools/testing/radix-tree/linux/rcupdate.h +++ b/tools/testing/radix-tree/linux/rcupdate.h @@ -7,6 +7,6 @@ #define rcu_dereference_raw(p) rcu_dereference(p) #define rcu_dereference_protected(p, cond) rcu_dereference(p) #define rcu_dereference_check(p, cond) rcu_dereference(p) -#define RCU_INIT_POINTER(p, v) (p) = (v) +#define RCU_INIT_POINTER(p, v) do { (p) = (v); } while (0) #endif diff --git a/tools/testing/selftests/rcutorture/Makefile b/tools/testing/selftests/rcutorture/Makefile new file mode 100644 index 000000000000..5202dc666206 --- /dev/null +++ b/tools/testing/selftests/rcutorture/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0+ +all: + ( cd ../../../..; tools/testing/selftests/rcutorture/bin/kvm.sh --duration 10 --configs TREE01 ) diff --git a/tools/testing/selftests/rcutorture/bin/configinit.sh b/tools/testing/selftests/rcutorture/bin/configinit.sh index 40359486b3a8..93e80a42249a 100755 --- a/tools/testing/selftests/rcutorture/bin/configinit.sh +++ b/tools/testing/selftests/rcutorture/bin/configinit.sh @@ -1,7 +1,7 @@ #!/bin/bash # SPDX-License-Identifier: GPL-2.0+ # -# Usage: configinit.sh config-spec-file build-output-dir results-dir +# Usage: configinit.sh config-spec-file results-dir # # Create a .config file from the spec file. Run from the kernel source tree. # Exits with 0 if all went well, with 1 if all went well but the config @@ -11,10 +11,6 @@ # desired settings, for example, "CONFIG_NO_HZ=y". For best results, # this should be a full pathname. # -# The second argument is a optional path to a build output directory, -# for example, "O=/tmp/foo". If this argument is omitted, the .config -# file will be generated directly in the current directory. -# # Copyright (C) IBM Corporation, 2013 # # Authors: Paul E. McKenney <paulmck@linux.ibm.com> @@ -26,34 +22,23 @@ mkdir $T # Capture config spec file. c=$1 -buildloc=$2 -resdir=$3 -builddir= -if echo $buildloc | grep -q '^O=' -then - builddir=`echo $buildloc | sed -e 's/^O=//'` - if test ! -d $builddir - then - mkdir $builddir - fi -else - echo Bad build directory: \"$buildloc\" - exit 2 -fi +resdir=$2 sed -e 's/^\(CONFIG[0-9A-Z_]*\)=.*$/grep -v "^# \1" |/' < $c > $T/u.sh sed -e 's/^\(CONFIG[0-9A-Z_]*=\).*$/grep -v \1 |/' < $c >> $T/u.sh grep '^grep' < $T/u.sh > $T/upd.sh echo "cat - $c" >> $T/upd.sh -make mrproper -make $buildloc distclean > $resdir/Make.distclean 2>&1 -make $buildloc $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1 -mv $builddir/.config $builddir/.config.sav -sh $T/upd.sh < $builddir/.config.sav > $builddir/.config -cp $builddir/.config $builddir/.config.new -yes '' | make $buildloc oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err +if test -z "$TORTURE_TRUST_MAKE" +then + make clean > $resdir/Make.clean 2>&1 +fi +make $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1 +mv .config .config.sav +sh $T/upd.sh < .config.sav > .config +cp .config .config.new +yes '' | make oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err # verify new config matches specification. -configcheck.sh $builddir/.config $c +configcheck.sh .config $c exit 0 diff --git a/tools/testing/selftests/rcutorture/bin/cpus2use.sh b/tools/testing/selftests/rcutorture/bin/cpus2use.sh index ff7102212703..4e9485590c10 100755 --- a/tools/testing/selftests/rcutorture/bin/cpus2use.sh +++ b/tools/testing/selftests/rcutorture/bin/cpus2use.sh @@ -9,6 +9,11 @@ # # Authors: Paul E. McKenney <paulmck@linux.ibm.com> +if test -n "$TORTURE_ALLOTED_CPUS" +then + echo $TORTURE_ALLOTED_CPUS + exit 0 +fi ncpus=`grep '^processor' /proc/cpuinfo | wc -l` idlecpus=`mpstat | tail -1 | \ awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }'` diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh index 6bcb8b5b2ff2..c3a49fb4d6f6 100644 --- a/tools/testing/selftests/rcutorture/bin/functions.sh +++ b/tools/testing/selftests/rcutorture/bin/functions.sh @@ -172,7 +172,7 @@ identify_qemu_append () { local console=ttyS0 case "$1" in qemu-system-x86_64|qemu-system-i386) - echo noapic selinux=0 initcall_debug debug + echo selinux=0 initcall_debug debug ;; qemu-system-aarch64) console=ttyAMA0 @@ -191,8 +191,19 @@ identify_qemu_append () { # Output arguments for qemu arguments based on the TORTURE_QEMU_MAC # and TORTURE_QEMU_INTERACTIVE environment variables. identify_qemu_args () { + local KVM_CPU="" + case "$1" in + qemu-system-x86_64) + KVM_CPU=kvm64 + ;; + qemu-system-i386) + KVM_CPU=kvm32 + ;; + esac case "$1" in qemu-system-x86_64|qemu-system-i386) + echo -machine q35,accel=kvm + echo -cpu ${KVM_CPU} ;; qemu-system-aarch64) echo -machine virt,gic-version=host -cpu host diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh index 435b60933985..dc49a3ba6111 100755 --- a/tools/testing/selftests/rcutorture/bin/jitter.sh +++ b/tools/testing/selftests/rcutorture/bin/jitter.sh @@ -34,10 +34,15 @@ do exit 0; fi - # Set affinity to randomly selected CPU - cpus=`ls /sys/devices/system/cpu/*/online | - sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' | - grep -v '^0*$'` + # Set affinity to randomly selected online CPU + cpus=`grep 1 /sys/devices/system/cpu/*/online | + sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//'` + + # Do not leave out poor old cpu0 which may not be hot-pluggable + if [ ! -f "/sys/devices/system/cpu/cpu0/online" ]; then + cpus="0 $cpus" + fi + cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN { srand(n + me + systime()); ncpus = split(cpus, ca); diff --git a/tools/testing/selftests/rcutorture/bin/kvm-build.sh b/tools/testing/selftests/rcutorture/bin/kvm-build.sh index c27a0bbb9c02..18d6518504ee 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-build.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-build.sh @@ -3,7 +3,7 @@ # # Build a kvm-ready Linux kernel from the tree in the current directory. # -# Usage: kvm-build.sh config-template build-dir resdir +# Usage: kvm-build.sh config-template resdir # # Copyright (C) IBM Corporation, 2011 # @@ -15,8 +15,7 @@ then echo "kvm-build.sh :$config_template: Not a readable file" exit 1 fi -builddir=${2} -resdir=${3} +resdir=${2} T=${TMPDIR-/tmp}/test-linux.sh.$$ trap 'rm -rf $T' 0 @@ -29,14 +28,14 @@ CONFIG_VIRTIO_PCI=y CONFIG_VIRTIO_CONSOLE=y ___EOF___ -configinit.sh $T/config O=$builddir $resdir +configinit.sh $T/config $resdir retval=$? if test $retval -gt 1 then exit 2 fi ncpus=`cpus2use.sh` -make O=$builddir -j$ncpus $TORTURE_KMAKE_ARG > $resdir/Make.out 2>&1 +make -j$ncpus $TORTURE_KMAKE_ARG > $resdir/Make.out 2>&1 retval=$? if test $retval -ne 0 || grep "rcu[^/]*": < $resdir/Make.out | egrep -q "Stop|Error|error:|warning:" || egrep -q "Stop|Error|error:" < $resdir/Make.out then diff --git a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh index 8426fe1f15ee..1871d00bccd7 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh @@ -11,6 +11,7 @@ # # The "directory" above should end with the date/time directory, for example, # "tools/testing/selftests/rcutorture/res/2018.02.25-14:27:27". +# Returns error status reflecting the success (or not) of the specified run. # # Copyright (C) IBM Corporation, 2018 # @@ -56,6 +57,8 @@ done if test -n "$files" then $editor $files + exit 1 else echo No errors in console logs. + exit 0 fi diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh index 2adde6aaafdb..e5edd5198725 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh @@ -7,6 +7,8 @@ # # Usage: kvm-recheck.sh resdir ... # +# Returns status reflecting the success or not of the last run specified. +# # Copyright (C) IBM Corporation, 2011 # # Authors: Paul E. McKenney <paulmck@linux.ibm.com> @@ -28,8 +30,16 @@ do TORTURE_SUITE="`cat $i/../TORTURE_SUITE`" rm -f $i/console.log.*.diags kvm-recheck-${TORTURE_SUITE}.sh $i - if test -f "$i/console.log" + if test -f "$i/qemu-retval" && test "`cat $i/qemu-retval`" -ne 0 && test "`cat $i/qemu-retval`" -ne 137 + then + echo QEMU error, output: + cat $i/qemu-output + elif test -f "$i/console.log" then + if test -f "$i/qemu-retval" && test "`cat $i/qemu-retval`" -eq 137 + then + echo QEMU killed + fi configcheck.sh $i/.config $i/ConfigFragment if test -r $i/Make.oldconfig.err then @@ -58,3 +68,4 @@ do fi done done +EDITOR=echo kvm-find-errors.sh "${@: -1}" > /dev/null 2>&1 diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh index 0eb1ec16d78a..27b7b5693ede 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh @@ -36,11 +36,6 @@ config_template=${1} config_dir=`echo $config_template | sed -e 's,/[^/]*$,,'` title=`echo $config_template | sed -e 's/^.*\///'` builddir=${2} -if test -z "$builddir" -o ! -d "$builddir" -o ! -w "$builddir" -then - echo "kvm-test-1-run.sh :$builddir: Not a writable directory, cannot build into it" - exit 1 -fi resdir=${3} if test -z "$resdir" -o ! -d "$resdir" -o ! -w "$resdir" then @@ -85,18 +80,18 @@ then ln -s $base_resdir/.config $resdir # for kvm-recheck.sh # Arch-independent indicator touch $resdir/builtkernel -elif kvm-build.sh $T/Kc2 $builddir $resdir +elif kvm-build.sh $T/Kc2 $resdir then # Had to build a kernel for this test. - QEMU="`identify_qemu $builddir/vmlinux`" + QEMU="`identify_qemu vmlinux`" BOOT_IMAGE="`identify_boot_image $QEMU`" - cp $builddir/vmlinux $resdir - cp $builddir/.config $resdir - cp $builddir/Module.symvers $resdir > /dev/null || : - cp $builddir/System.map $resdir > /dev/null || : + cp vmlinux $resdir + cp .config $resdir + cp Module.symvers $resdir > /dev/null || : + cp System.map $resdir > /dev/null || : if test -n "$BOOT_IMAGE" then - cp $builddir/$BOOT_IMAGE $resdir + cp $BOOT_IMAGE $resdir KERNEL=$resdir/${BOOT_IMAGE##*/} # Arch-independent indicator touch $resdir/builtkernel @@ -107,7 +102,7 @@ then parse-build.sh $resdir/Make.out $title else # Build failed. - cp $builddir/.config $resdir || : + cp .config $resdir || : echo Build failed, not running KVM, see $resdir. if test -f $builddir.wait then @@ -165,7 +160,7 @@ then fi echo "NOTE: $QEMU either did not run or was interactive" > $resdir/console.log echo $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append \"$qemu_append $boot_args\" > $resdir/qemu-cmd -( $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append "$qemu_append $boot_args"& echo $! > $resdir/qemu_pid; wait `cat $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) & +( $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append "$qemu_append $boot_args" > $resdir/qemu-output 2>&1 & echo $! > $resdir/qemu_pid; wait `cat $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) & commandcompleted=0 sleep 10 # Give qemu's pid a chance to reach the file if test -s "$resdir/qemu_pid" diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh index 8f1e337b9b54..72518580df23 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh @@ -24,6 +24,7 @@ dur=$((30*60)) dryrun="" KVM="`pwd`/tools/testing/selftests/rcutorture"; export KVM PATH=${KVM}/bin:$PATH; export PATH +TORTURE_ALLOTED_CPUS="" TORTURE_DEFCONFIG=defconfig TORTURE_BOOT_IMAGE="" TORTURE_INITRD="$KVM/initrd"; export TORTURE_INITRD @@ -32,6 +33,7 @@ TORTURE_KMAKE_ARG="" TORTURE_QEMU_MEM=512 TORTURE_SHUTDOWN_GRACE=180 TORTURE_SUITE=rcu +TORTURE_TRUST_MAKE="" resdir="" configs="" cpus=0 @@ -62,6 +64,7 @@ usage () { echo " --qemu-cmd qemu-system-..." echo " --results absolute-pathname" echo " --torture rcu" + echo " --trust-make" exit 1 } @@ -89,6 +92,7 @@ do --cpus) checkarg --cpus "(number)" "$#" "$2" '^[0-9]*$' '^--' cpus=$2 + TORTURE_ALLOTED_CPUS="$2" shift ;; --datestamp) @@ -173,6 +177,9 @@ do jitter=0 fi ;; + --trust-make) + TORTURE_TRUST_MAKE="y" + ;; *) echo Unknown argument $1 usage @@ -285,6 +292,7 @@ cat << ___EOF___ > $T/script CONFIGFRAG="$CONFIGFRAG"; export CONFIGFRAG KVM="$KVM"; export KVM PATH="$PATH"; export PATH +TORTURE_ALLOTED_CPUS="$TORTURE_ALLOTED_CPUS"; export TORTURE_ALLOTED_CPUS TORTURE_BOOT_IMAGE="$TORTURE_BOOT_IMAGE"; export TORTURE_BOOT_IMAGE TORTURE_BUILDONLY="$TORTURE_BUILDONLY"; export TORTURE_BUILDONLY TORTURE_DEFCONFIG="$TORTURE_DEFCONFIG"; export TORTURE_DEFCONFIG @@ -297,6 +305,7 @@ TORTURE_QEMU_MAC="$TORTURE_QEMU_MAC"; export TORTURE_QEMU_MAC TORTURE_QEMU_MEM="$TORTURE_QEMU_MEM"; export TORTURE_QEMU_MEM TORTURE_SHUTDOWN_GRACE="$TORTURE_SHUTDOWN_GRACE"; export TORTURE_SHUTDOWN_GRACE TORTURE_SUITE="$TORTURE_SUITE"; export TORTURE_SUITE +TORTURE_TRUST_MAKE="$TORTURE_TRUST_MAKE"; export TORTURE_TRUST_MAKE if ! test -e $resdir then mkdir -p "$resdir" || : @@ -342,7 +351,7 @@ function dump(first, pastlast, batchnum) print "needqemurun=" jn=1 for (j = first; j < pastlast; j++) { - builddir=KVM "/b1" + builddir=KVM "/b" j - first + 1 cpusr[jn] = cpus[j]; if (cfrep[cf[j]] == "") { cfr[jn] = cf[j]; @@ -358,7 +367,6 @@ function dump(first, pastlast, batchnum) print "echo ", cfr[jn], cpusr[jn] ovf ": Starting build. `date` | tee -a " rd "log"; print "rm -f " builddir ".*"; print "touch " builddir ".wait"; - print "mkdir " builddir " > /dev/null 2>&1 || :"; print "mkdir " rd cfr[jn] " || :"; print "kvm-test-1-run.sh " CONFIGDIR cf[j], builddir, rd cfr[jn], dur " \"" TORTURE_QEMU_ARG "\" \"" TORTURE_BOOTARGS "\" > " rd cfr[jn] "/kvm-test-1-run.sh.out 2>&1 &" print "echo ", cfr[jn], cpusr[jn] ovf ": Waiting for build to complete. `date` | tee -a " rd "log"; @@ -464,3 +472,5 @@ else fi # Tracing: trace_event=rcu:rcu_grace_period,rcu:rcu_future_grace_period,rcu:rcu_grace_period_init,rcu:rcu_nocb_wake,rcu:rcu_preempt_task,rcu:rcu_unlock_preempted_task,rcu:rcu_quiescent_state_report,rcu:rcu_fqs,rcu:rcu_callback,rcu:rcu_kfree_callback,rcu:rcu_batch_start,rcu:rcu_invoke_callback,rcu:rcu_invoke_kfree_callback,rcu:rcu_batch_end,rcu:rcu_torture_read,rcu:rcu_barrier +# Function-graph tracing: ftrace=function_graph ftrace_graph_filter=sched_setaffinity,migration_cpu_stop +# Also --kconfig "CONFIG_FUNCTION_TRACER=y CONFIG_FUNCTION_GRAPH_TRACER=y" diff --git a/tools/testing/selftests/rcutorture/bin/parse-build.sh b/tools/testing/selftests/rcutorture/bin/parse-build.sh index 0701b3bf6ade..09155c15ea65 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-build.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-build.sh @@ -21,7 +21,7 @@ mkdir $T . functions.sh -if grep -q CC < $F +if grep -q CC < $F || test -n "$TORTURE_TRUST_MAKE" then : else diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh index 4508373a922f..4bf62d7b1cbc 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-console.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh @@ -106,6 +106,7 @@ fi | tee -a $file.diags egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state|rcu_.*kthread starved for' < $file | grep -v 'ODEBUG: ' | +grep -v 'This means that this is a DEBUG kernel and it is' | grep -v 'Warning: unable to open an initial console' > $T.diags if test -s $T.diags then diff --git a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon index d2d2a86139db..e19a444a0684 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon +++ b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon @@ -1,2 +1,5 @@ CONFIG_RCU_TORTURE_TEST=y CONFIG_PRINTK_TIME=y +CONFIG_HYPERVISOR_GUEST=y +CONFIG_PARAVIRT=y +CONFIG_KVM_GUEST=y diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot index ea47da95374b..d6da9a61d44a 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot @@ -3,3 +3,4 @@ rcutree.gp_preinit_delay=3 rcutree.gp_init_delay=3 rcutree.gp_cleanup_delay=3 rcu_nocbs=0 +rcutorture.fwd_progress=0 diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL new file mode 100644 index 000000000000..4d8eb5bfb6f6 --- /dev/null +++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL @@ -0,0 +1,14 @@ +CONFIG_SMP=y +CONFIG_NR_CPUS=8 +CONFIG_PREEMPT_NONE=y +CONFIG_PREEMPT_VOLUNTARY=n +CONFIG_PREEMPT=n +CONFIG_HZ_PERIODIC=n +CONFIG_NO_HZ_IDLE=y +CONFIG_NO_HZ_FULL=n +CONFIG_HOTPLUG_CPU=n +CONFIG_SUSPEND=n +CONFIG_HIBERNATION=n +CONFIG_DEBUG_LOCK_ALLOC=n +CONFIG_DEBUG_OBJECTS_RCU_HEAD=n +CONFIG_RCU_EXPERT=y diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot new file mode 100644 index 000000000000..7017f5f5a55f --- /dev/null +++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot @@ -0,0 +1,3 @@ +rcutorture.torture_type=trivial +rcutorture.onoff_interval=0 +rcutorture.shuffle_interval=0 |