From f9010dbdce911ee1f1af1398a24b1f9f992e0080 Mon Sep 17 00:00:00 2001 From: Mike Christie Date: Thu, 1 Jun 2023 13:32:32 -0500 Subject: fork, vhost: Use CLONE_THREAD to fix freezer/ps regression When switching from kthreads to vhost_tasks two bugs were added: 1. The vhost worker tasks's now show up as processes so scripts doing ps or ps a would not incorrectly detect the vhost task as another process. 2. kthreads disabled freeze by setting PF_NOFREEZE, but vhost tasks's didn't disable or add support for them. To fix both bugs, this switches the vhost task to be thread in the process that does the VHOST_SET_OWNER ioctl, and has vhost_worker call get_signal to support SIGKILL/SIGSTOP and freeze signals. Note that SIGKILL/STOP support is required because CLONE_THREAD requires CLONE_SIGHAND which requires those 2 signals to be supported. This is a modified version of the patch written by Mike Christie which was a modified version of patch originally written by Linus. Much of what depended upon PF_IO_WORKER now depends on PF_USER_WORKER. Including ignoring signals, setting up the register state, and having get_signal return instead of calling do_group_exit. Tidied up the vhost_task abstraction so that the definition of vhost_task only needs to be visible inside of vhost_task.c. Making it easier to review the code and tell what needs to be done where. As part of this the main loop has been moved from vhost_worker into vhost_task_fn. vhost_worker now returns true if work was done. The main loop has been updated to call get_signal which handles SIGSTOP, freezing, and collects the message that tells the thread to exit as part of process exit. This collection clears __fatal_signal_pending. This collection is not guaranteed to clear signal_pending() so clear that explicitly so the schedule() sleeps. For now the vhost thread continues to exist and run work until the last file descriptor is closed and the release function is called as part of freeing struct file. To avoid hangs in the coredump rendezvous and when killing threads in a multi-threaded exec. The coredump code and de_thread have been modified to ignore vhost threads. Remvoing the special case for exec appears to require teaching vhost_dev_flush how to directly complete transactions in case the vhost thread is no longer running. Removing the special case for coredump rendezvous requires either the above fix needed for exec or moving the coredump rendezvous into get_signal. Fixes: 6e890c5d5021 ("vhost: use vhost_tasks for worker threads") Signed-off-by: Eric W. Biederman Co-developed-by: Mike Christie Signed-off-by: Mike Christie Acked-by: Michael S. Tsirkin Signed-off-by: Linus Torvalds --- include/linux/sched/task.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/sched/task.h') diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index 537cbf9a2ade..e0f5ac90a228 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -29,7 +29,6 @@ struct kernel_clone_args { u32 io_thread:1; u32 user_worker:1; u32 no_files:1; - u32 ignore_signals:1; unsigned long stack; unsigned long stack_size; unsigned long tls; -- cgit v1.2.3 From 54da6a0924311c7cf5015533991e44fb8eb12773 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 26 May 2023 12:23:48 +0200 Subject: locking: Introduce __cleanup() based infrastructure Use __attribute__((__cleanup__(func))) to build: - simple auto-release pointers using __free() - 'classes' with constructor and destructor semantics for scope-based resource management. - lock guards based on the above classes. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org --- include/linux/cleanup.h | 171 ++++++++++++++++++++++++++++++++++++ include/linux/compiler-clang.h | 9 ++ include/linux/compiler_attributes.h | 6 ++ include/linux/device.h | 7 ++ include/linux/file.h | 6 ++ include/linux/irqflags.h | 7 ++ include/linux/mutex.h | 4 + include/linux/percpu.h | 4 + include/linux/preempt.h | 5 ++ include/linux/rcupdate.h | 3 + include/linux/rwsem.h | 8 ++ include/linux/sched/task.h | 2 + include/linux/slab.h | 3 + include/linux/spinlock.h | 31 +++++++ include/linux/srcu.h | 5 ++ scripts/checkpatch.pl | 2 +- 16 files changed, 272 insertions(+), 1 deletion(-) create mode 100644 include/linux/cleanup.h (limited to 'include/linux/sched/task.h') diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h new file mode 100644 index 000000000000..53f1a7a932b0 --- /dev/null +++ b/include/linux/cleanup.h @@ -0,0 +1,171 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_GUARDS_H +#define __LINUX_GUARDS_H + +#include + +/* + * DEFINE_FREE(name, type, free): + * simple helper macro that defines the required wrapper for a __free() + * based cleanup function. @free is an expression using '_T' to access + * the variable. + * + * __free(name): + * variable attribute to add a scoped based cleanup to the variable. + * + * no_free_ptr(var): + * like a non-atomic xchg(var, NULL), such that the cleanup function will + * be inhibited -- provided it sanely deals with a NULL value. + * + * return_ptr(p): + * returns p while inhibiting the __free(). + * + * Ex. + * + * DEFINE_FREE(kfree, void *, if (_T) kfree(_T)) + * + * struct obj *p __free(kfree) = kmalloc(...); + * if (!p) + * return NULL; + * + * if (!init_obj(p)) + * return NULL; + * + * return_ptr(p); + */ + +#define DEFINE_FREE(_name, _type, _free) \ + static inline void __free_##_name(void *p) { _type _T = *(_type *)p; _free; } + +#define __free(_name) __cleanup(__free_##_name) + +#define no_free_ptr(p) \ + ({ __auto_type __ptr = (p); (p) = NULL; __ptr; }) + +#define return_ptr(p) return no_free_ptr(p) + + +/* + * DEFINE_CLASS(name, type, exit, init, init_args...): + * helper to define the destructor and constructor for a type. + * @exit is an expression using '_T' -- similar to FREE above. + * @init is an expression in @init_args resulting in @type + * + * EXTEND_CLASS(name, ext, init, init_args...): + * extends class @name to @name@ext with the new constructor + * + * CLASS(name, var)(args...): + * declare the variable @var as an instance of the named class + * + * Ex. + * + * DEFINE_CLASS(fdget, struct fd, fdput(_T), fdget(fd), int fd) + * + * CLASS(fdget, f)(fd); + * if (!f.file) + * return -EBADF; + * + * // use 'f' without concern + */ + +#define DEFINE_CLASS(_name, _type, _exit, _init, _init_args...) \ +typedef _type class_##_name##_t; \ +static inline void class_##_name##_destructor(_type *p) \ +{ _type _T = *p; _exit; } \ +static inline _type class_##_name##_constructor(_init_args) \ +{ _type t = _init; return t; } + +#define EXTEND_CLASS(_name, ext, _init, _init_args...) \ +typedef class_##_name##_t class_##_name##ext##_t; \ +static inline void class_##_name##ext##_destructor(class_##_name##_t *p)\ +{ class_##_name##_destructor(p); } \ +static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ +{ class_##_name##_t t = _init; return t; } + +#define CLASS(_name, var) \ + class_##_name##_t var __cleanup(class_##_name##_destructor) = \ + class_##_name##_constructor + + +/* + * DEFINE_GUARD(name, type, lock, unlock): + * trivial wrapper around DEFINE_CLASS() above specifically + * for locks. + * + * guard(name): + * an anonymous instance of the (guard) class + * + * scoped_guard (name, args...) { }: + * similar to CLASS(name, scope)(args), except the variable (with the + * explicit name 'scope') is declard in a for-loop such that its scope is + * bound to the next (compound) statement. + * + */ + +#define DEFINE_GUARD(_name, _type, _lock, _unlock) \ + DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T) + +#define guard(_name) \ + CLASS(_name, __UNIQUE_ID(guard)) + +#define scoped_guard(_name, args...) \ + for (CLASS(_name, scope)(args), \ + *done = NULL; !done; done = (void *)1) + +/* + * Additional helper macros for generating lock guards with types, either for + * locks that don't have a native type (eg. RCU, preempt) or those that need a + * 'fat' pointer (eg. spin_lock_irqsave). + * + * DEFINE_LOCK_GUARD_0(name, lock, unlock, ...) + * DEFINE_LOCK_GUARD_1(name, type, lock, unlock, ...) + * + * will result in the following type: + * + * typedef struct { + * type *lock; // 'type := void' for the _0 variant + * __VA_ARGS__; + * } class_##name##_t; + * + * As above, both _lock and _unlock are statements, except this time '_T' will + * be a pointer to the above struct. + */ + +#define __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, ...) \ +typedef struct { \ + _type *lock; \ + __VA_ARGS__; \ +} class_##_name##_t; \ + \ +static inline void class_##_name##_destructor(class_##_name##_t *_T) \ +{ \ + if (_T->lock) { _unlock; } \ +} + + +#define __DEFINE_LOCK_GUARD_1(_name, _type, _lock) \ +static inline class_##_name##_t class_##_name##_constructor(_type *l) \ +{ \ + class_##_name##_t _t = { .lock = l }, *_T = &_t; \ + _lock; \ + return _t; \ +} + +#define __DEFINE_LOCK_GUARD_0(_name, _lock) \ +static inline class_##_name##_t class_##_name##_constructor(void) \ +{ \ + class_##_name##_t _t = { .lock = (void*)1 }, \ + *_T __maybe_unused = &_t; \ + _lock; \ + return _t; \ +} + +#define DEFINE_LOCK_GUARD_1(_name, _type, _lock, _unlock, ...) \ +__DEFINE_UNLOCK_GUARD(_name, _type, _unlock, __VA_ARGS__) \ +__DEFINE_LOCK_GUARD_1(_name, _type, _lock) + +#define DEFINE_LOCK_GUARD_0(_name, _lock, _unlock, ...) \ +__DEFINE_UNLOCK_GUARD(_name, void, _unlock, __VA_ARGS__) \ +__DEFINE_LOCK_GUARD_0(_name, _lock) + +#endif /* __LINUX_GUARDS_H */ diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 6cfd6902bd5b..9b673fefcef8 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -5,6 +5,15 @@ /* Compiler specific definitions for Clang compiler */ +/* + * Clang prior to 17 is being silly and considers many __cleanup() variables + * as unused (because they are, their sole purpose is to go out of scope). + * + * https://reviews.llvm.org/D152180 + */ +#undef __cleanup +#define __cleanup(func) __maybe_unused __attribute__((__cleanup__(func))) + /* same as gcc, this was present in clang-2.6 so we can assume it works * with any version that can compile the kernel */ diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index e659cb6fded3..081deaef1f0f 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -69,6 +69,12 @@ */ #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) +/* + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cleanup-variable-attribute + * clang: https://clang.llvm.org/docs/AttributeReference.html#cleanup + */ +#define __cleanup(func) __attribute__((__cleanup__(func))) + /* * Note the long name. * diff --git a/include/linux/device.h b/include/linux/device.h index 472dd24d4823..2b64268d776c 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -30,6 +30,7 @@ #include #include #include +#include #include struct device; @@ -899,6 +900,9 @@ void device_unregister(struct device *dev); void device_initialize(struct device *dev); int __must_check device_add(struct device *dev); void device_del(struct device *dev); + +DEFINE_FREE(device_del, struct device *, if (_T) device_del(_T)) + int device_for_each_child(struct device *dev, void *data, int (*fn)(struct device *dev, void *data)); int device_for_each_child_reverse(struct device *dev, void *data, @@ -1066,6 +1070,9 @@ extern int (*platform_notify_remove)(struct device *dev); */ struct device *get_device(struct device *dev); void put_device(struct device *dev); + +DEFINE_FREE(put_device, struct device *, if (_T) put_device(_T)) + bool kill_device(struct device *dev); #ifdef CONFIG_DEVTMPFS diff --git a/include/linux/file.h b/include/linux/file.h index 39704eae83e2..6e9099d29343 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -10,6 +10,7 @@ #include #include #include +#include struct file; @@ -80,6 +81,8 @@ static inline void fdput_pos(struct fd f) fdput(f); } +DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd) + extern int f_dupfd(unsigned int from, struct file *file, unsigned flags); extern int replace_fd(unsigned fd, struct file *file, unsigned flags); extern void set_close_on_exec(unsigned int fd, int flag); @@ -88,6 +91,9 @@ extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile); extern int get_unused_fd_flags(unsigned flags); extern void put_unused_fd(unsigned int fd); +DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T), + get_unused_fd_flags(flags), unsigned flags) + extern void fd_install(unsigned int fd, struct file *file); extern int __receive_fd(struct file *file, int __user *ufd, diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 5ec0fa71399e..2b665c32f5fe 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -13,6 +13,7 @@ #define _LINUX_TRACE_IRQFLAGS_H #include +#include #include #include @@ -267,4 +268,10 @@ extern void warn_bogus_irq_restore(void); #define irqs_disabled_flags(flags) raw_irqs_disabled_flags(flags) +DEFINE_LOCK_GUARD_0(irq, local_irq_disable(), local_irq_enable()) +DEFINE_LOCK_GUARD_0(irqsave, + local_irq_save(_T->flags), + local_irq_restore(_T->flags), + unsigned long flags) + #endif diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 8f226d460f51..a33aa9eb9fc3 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -19,6 +19,7 @@ #include #include #include +#include #ifdef CONFIG_DEBUG_LOCK_ALLOC # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ @@ -219,4 +220,7 @@ extern void mutex_unlock(struct mutex *lock); extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); +DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T)) +DEFINE_FREE(mutex, struct mutex *, if (_T) mutex_unlock(_T)) + #endif /* __LINUX_MUTEX_H */ diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 1338ea2aa720..d33ab1799932 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -8,6 +8,7 @@ #include #include #include +#include #include @@ -127,6 +128,9 @@ extern void __init setup_per_cpu_areas(void); extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) __alloc_size(1); extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_size(1); extern void free_percpu(void __percpu *__pdata); + +DEFINE_FREE(free_percpu, void __percpu *, free_percpu(_T)) + extern phys_addr_t per_cpu_ptr_to_phys(void *addr); #define alloc_percpu_gfp(type, gfp) \ diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 0df425bf9bd7..1424670df161 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -8,6 +8,7 @@ */ #include +#include #include /* @@ -463,4 +464,8 @@ static __always_inline void preempt_enable_nested(void) preempt_enable(); } +DEFINE_LOCK_GUARD_0(preempt, preempt_disable(), preempt_enable()) +DEFINE_LOCK_GUARD_0(preempt_notrace, preempt_disable_notrace(), preempt_enable_notrace()) +DEFINE_LOCK_GUARD_0(migrate, migrate_disable(), migrate_enable()) + #endif /* __LINUX_PREEMPT_H */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index dcd2cf1e8326..7aa090329ba2 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -1095,4 +1096,6 @@ rcu_head_after_call_rcu(struct rcu_head *rhp, rcu_callback_t f) extern int rcu_expedited; extern int rcu_normal; +DEFINE_LOCK_GUARD_0(rcu, rcu_read_lock(), rcu_read_unlock()) + #endif /* __LINUX_RCUPDATE_H */ diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index efa5c324369a..1dd530ce8b45 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -15,6 +15,7 @@ #include #include #include +#include #ifdef CONFIG_DEBUG_LOCK_ALLOC # define __RWSEM_DEP_MAP_INIT(lockname) \ @@ -201,6 +202,13 @@ extern void up_read(struct rw_semaphore *sem); */ extern void up_write(struct rw_semaphore *sem); +DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T)) +DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T)) + +DEFINE_FREE(up_read, struct rw_semaphore *, if (_T) up_read(_T)) +DEFINE_FREE(up_write, struct rw_semaphore *, if (_T) up_write(_T)) + + /* * downgrade write lock to read lock */ diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index e0f5ac90a228..dd35ce28bb90 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -125,6 +125,8 @@ static inline void put_task_struct(struct task_struct *t) __put_task_struct(t); } +DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T)) + static inline void put_task_struct_many(struct task_struct *t, int nr) { if (refcount_sub_and_test(nr, &t->usage)) diff --git a/include/linux/slab.h b/include/linux/slab.h index 6b3e155b70bf..c1fb57d6107c 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -17,6 +17,7 @@ #include #include #include +#include /* @@ -211,6 +212,8 @@ void kfree(const void *objp); void kfree_sensitive(const void *objp); size_t __ksize(const void *objp); +DEFINE_FREE(kfree, void *, if (_T) kfree(_T)) + /** * ksize - Report actual allocation size of associated object * diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index be48f1cb1878..31d3d747a9db 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -61,6 +61,7 @@ #include #include #include +#include #include #include @@ -502,5 +503,35 @@ int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask, void free_bucket_spinlocks(spinlock_t *locks); +DEFINE_LOCK_GUARD_1(raw_spinlock, raw_spinlock_t, + raw_spin_lock(_T->lock), + raw_spin_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(raw_spinlock_nested, raw_spinlock_t, + raw_spin_lock_nested(_T->lock, SINGLE_DEPTH_NESTING), + raw_spin_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(raw_spinlock_irq, raw_spinlock_t, + raw_spin_lock_irq(_T->lock), + raw_spin_unlock_irq(_T->lock)) + +DEFINE_LOCK_GUARD_1(raw_spinlock_irqsave, raw_spinlock_t, + raw_spin_lock_irqsave(_T->lock, _T->flags), + raw_spin_unlock_irqrestore(_T->lock, _T->flags), + unsigned long flags) + +DEFINE_LOCK_GUARD_1(spinlock, spinlock_t, + spin_lock(_T->lock), + spin_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(spinlock_irq, spinlock_t, + spin_lock_irq(_T->lock), + spin_unlock_irq(_T->lock)) + +DEFINE_LOCK_GUARD_1(spinlock_irqsave, spinlock_t, + spin_lock_irqsave(_T->lock, _T->flags), + spin_unlock_irqrestore(_T->lock, _T->flags), + unsigned long flags) + #undef __LINUX_INSIDE_SPINLOCK_H #endif /* __LINUX_SPINLOCK_H */ diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 41c4b26fb1c1..b3b1def982dd 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -343,4 +343,9 @@ static inline void smp_mb__after_srcu_read_unlock(void) /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ } +DEFINE_LOCK_GUARD_1(srcu, struct srcu_struct, + _T->idx = srcu_read_lock(_T->lock), + srcu_read_unlock(_T->lock, _T->idx), + int idx) + #endif diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index b30114d637c4..3a6df9c2977b 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -5046,7 +5046,7 @@ sub process { if|for|while|switch|return|case| volatile|__volatile__| __attribute__|format|__extension__| - asm|__asm__)$/x) + asm|__asm__|scoped_guard)$/x) { # cpp #define statements have non-optional spaces, ie # if there is a space between the name and the open -- cgit v1.2.3