From 091541bbdb9906349481a504e7d8e7fa89f6b6bb Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 10 Jan 2012 12:51:14 -0800 Subject: rcu: Make rcutorture flag online/offline failures Make rcutorture check for CPU-hotplug failures and complain if there were any. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutorture.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/rcutorture.c') diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index a58ac285fc69..a52b3217c160 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -1602,6 +1602,10 @@ rcu_torture_cleanup(void) cur_ops->cleanup(); if (atomic_read(&n_rcu_torture_error)) rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE"); + else if (n_online_successes != n_online_attempts || + n_offline_successes != n_offline_attempts) + rcu_torture_print_module_parms(cur_ops, + "End of test: RCU_HOTPLUG"); else rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS"); } -- cgit v1.2.3 From 9b9ec9b90ef481e182927989963274dc2697f9a6 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 17 Jan 2012 14:36:51 -0800 Subject: rcutorture: Permit holding off CPU-hotplug operations during boot When rcutorture is started automatically at boot time, it might well also start CPU-hotplug operations at that time, which might not be desirable. This commit therefore adds an rcutorture parameter that allows CPU-hotplug operations to be held off for the specified number of seconds after the start of boot. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- Documentation/RCU/torture.txt | 13 +++++++++++-- kernel/rcutorture.c | 12 ++++++++++-- 2 files changed, 21 insertions(+), 4 deletions(-) (limited to 'kernel/rcutorture.c') diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt index d67068d0d2b9..01a809b1dbc6 100644 --- a/Documentation/RCU/torture.txt +++ b/Documentation/RCU/torture.txt @@ -69,6 +69,13 @@ onoff_interval CPU-hotplug operations regardless of what value is specified for onoff_interval. +onoff_holdoff The number of seconds to wait until starting CPU-hotplug + operations. This would normally only be used when + rcutorture was built into the kernel and started + automatically at boot time, in which case it is useful + in order to avoid confusing boot-time code with CPUs + coming and going. + shuffle_interval The number of seconds to keep the test threads affinitied to a particular subset of the CPUs, defaults to 3 seconds. @@ -277,5 +284,7 @@ The following script may be used to torture RCU: The output can be manually inspected for the error flag of "!!!". One could of course create a more elaborate script that automatically -checked for such errors. The "rmmod" command forces a "SUCCESS" or -"FAILURE" indication to be printk()ed. +checked for such errors. The "rmmod" command forces a "SUCCESS", +"FAILURE", or "RCU_HOTPLUG" indication to be printk()ed. The first +two are self-explanatory, while the last indicates that while there +were no RCU failures, CPU-hotplug problems were detected. diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index a52b3217c160..2914cafe171b 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -65,6 +65,7 @@ static int fqs_duration; /* Duration of bursts (us), 0 to disable. */ static int fqs_holdoff; /* Hold time within burst (us). */ static int fqs_stutter = 3; /* Wait time between bursts (s). */ static int onoff_interval; /* Wait time between CPU hotplugs, 0=disable. */ +static int onoff_holdoff; /* Seconds after boot before CPU hotplugs. */ static int shutdown_secs; /* Shutdown time (s). <=0 for no shutdown. */ static int test_boost = 1; /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */ static int test_boost_interval = 7; /* Interval between boost tests, seconds. */ @@ -95,6 +96,8 @@ module_param(fqs_stutter, int, 0444); MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)"); module_param(onoff_interval, int, 0444); MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable"); +module_param(onoff_holdoff, int, 0444); +MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)"); module_param(shutdown_secs, int, 0444); MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable."); module_param(test_boost, int, 0444); @@ -1300,13 +1303,13 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag) "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d " "test_boost=%d/%d test_boost_interval=%d " "test_boost_duration=%d shutdown_secs=%d " - "onoff_interval=%d\n", + "onoff_interval=%d onoff_holdoff=%d\n", torture_type, tag, nrealreaders, nfakewriters, stat_interval, verbose, test_no_idle_hz, shuffle_interval, stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter, test_boost, cur_ops->can_boost, test_boost_interval, test_boost_duration, shutdown_secs, - onoff_interval); + onoff_interval, onoff_holdoff); } static struct notifier_block rcutorture_shutdown_nb = { @@ -1410,6 +1413,11 @@ rcu_torture_onoff(void *arg) for_each_online_cpu(cpu) maxcpu = cpu; WARN_ON(maxcpu < 0); + if (onoff_holdoff > 0) { + VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff"); + schedule_timeout_interruptible(onoff_holdoff * HZ); + VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff"); + } while (!kthread_should_stop()) { cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1); if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) { -- cgit v1.2.3 From c13f3757d0fcdcc2b7fc5d5e38da76b8913e6648 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 20 Jan 2012 15:36:33 -0800 Subject: rcu: Add CPU-stall capability to rcutorture Add module parameters to rcutorture that induce a CPU stall. The stall_cpu parameter specifies how long to stall in seconds, defaulting to zero, which indicates no stalling is to be undertaken. The stall_cpu_holdoff parameter specifies how many seconds after insmod (or boot, if rcutorture is built into the kernel) that this stall is to start. The default value for stall_cpu_holdoff is ten seconds. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- Documentation/RCU/torture.txt | 18 ++++++++++++ kernel/rcutorture.c | 66 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 84 insertions(+) (limited to 'kernel/rcutorture.c') diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt index d25be872ae33..375d3fb71437 100644 --- a/Documentation/RCU/torture.txt +++ b/Documentation/RCU/torture.txt @@ -86,6 +86,24 @@ shutdown_secs The number of seconds to run the test before terminating zero, which disables test termination and system shutdown. This capability is useful for automated testing. +stall_cpu The number of seconds that a CPU should be stalled while + within both an rcu_read_lock() and a preempt_disable(). + This stall happens only once per rcutorture run. + If you need multiple stalls, use modprobe and rmmod to + repeatedly run rcutorture. The default for stall_cpu + is zero, which prevents rcutorture from stalling a CPU. + + Note that attempts to rmmod rcutorture while the stall + is ongoing will hang, so be careful what value you + choose for this module parameter! In addition, too-large + values for stall_cpu might well induce failures and + warnings in other parts of the kernel. You have been + warned! + +stall_cpu_holdoff + The number of seconds to wait after rcutorture starts + before stalling a CPU. Defaults to 10 seconds. + stat_interval The number of seconds between output of torture statistics (via printk()). Regardless of the interval, statistics are printed when the module is unloaded. diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 2914cafe171b..5cfa23be43bd 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -67,6 +67,8 @@ static int fqs_stutter = 3; /* Wait time between bursts (s). */ static int onoff_interval; /* Wait time between CPU hotplugs, 0=disable. */ static int onoff_holdoff; /* Seconds after boot before CPU hotplugs. */ static int shutdown_secs; /* Shutdown time (s). <=0 for no shutdown. */ +static int stall_cpu; /* CPU-stall duration (s). 0 for no stall. */ +static int stall_cpu_holdoff = 10; /* Time to wait until stall (s). */ static int test_boost = 1; /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */ static int test_boost_interval = 7; /* Interval between boost tests, seconds. */ static int test_boost_duration = 4; /* Duration of each boost test, seconds. */ @@ -100,6 +102,10 @@ module_param(onoff_holdoff, int, 0444); MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)"); module_param(shutdown_secs, int, 0444); MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable."); +module_param(stall_cpu, int, 0444); +MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable."); +module_param(stall_cpu_holdoff, int, 0444); +MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s)."); module_param(test_boost, int, 0444); MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes."); module_param(test_boost_interval, int, 0444); @@ -132,6 +138,7 @@ static struct task_struct *shutdown_task; #ifdef CONFIG_HOTPLUG_CPU static struct task_struct *onoff_task; #endif /* #ifdef CONFIG_HOTPLUG_CPU */ +static struct task_struct *stall_task; #define RCU_TORTURE_PIPE_LEN 10 @@ -1489,6 +1496,63 @@ static void rcu_torture_onoff_cleanup(void) #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ +/* + * CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then + * induces a CPU stall for the time specified by stall_cpu. + */ +static int __cpuinit rcu_torture_stall(void *args) +{ + unsigned long stop_at; + + VERBOSE_PRINTK_STRING("rcu_torture_stall task started"); + if (stall_cpu_holdoff > 0) { + VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff"); + schedule_timeout_interruptible(stall_cpu_holdoff * HZ); + VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff"); + } + if (!kthread_should_stop()) { + stop_at = get_seconds() + stall_cpu; + /* RCU CPU stall is expected behavior in following code. */ + printk(KERN_ALERT "rcu_torture_stall start.\n"); + rcu_read_lock(); + preempt_disable(); + while (ULONG_CMP_LT(get_seconds(), stop_at)) + continue; /* Induce RCU CPU stall warning. */ + preempt_enable(); + rcu_read_unlock(); + printk(KERN_ALERT "rcu_torture_stall end.\n"); + } + rcutorture_shutdown_absorb("rcu_torture_stall"); + while (!kthread_should_stop()) + schedule_timeout_interruptible(10 * HZ); + return 0; +} + +/* Spawn CPU-stall kthread, if stall_cpu specified. */ +static int __init rcu_torture_stall_init(void) +{ + int ret; + + if (stall_cpu <= 0) + return 0; + stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall"); + if (IS_ERR(stall_task)) { + ret = PTR_ERR(stall_task); + stall_task = NULL; + return ret; + } + return 0; +} + +/* Clean up after the CPU-stall kthread, if one was spawned. */ +static void rcu_torture_stall_cleanup(void) +{ + if (stall_task == NULL) + return; + VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task."); + kthread_stop(stall_task); +} + static int rcutorture_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { @@ -1531,6 +1595,7 @@ rcu_torture_cleanup(void) fullstop = FULLSTOP_RMMOD; mutex_unlock(&fullstop_mutex); unregister_reboot_notifier(&rcutorture_shutdown_nb); + rcu_torture_stall_cleanup(); if (stutter_task) { VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task"); kthread_stop(stutter_task); @@ -1831,6 +1896,7 @@ rcu_torture_init(void) } rcu_torture_onoff_init(); register_reboot_notifier(&rcutorture_shutdown_nb); + rcu_torture_stall_init(); rcutorture_record_test_transition(); mutex_unlock(&fullstop_mutex); return 0; -- cgit v1.2.3 From 7129d383d9f46eb8276bee5fb46df63f09a70130 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 31 Jan 2012 16:46:34 -0800 Subject: rcu: Trace only after NULL-pointer check Fix a bonehead error introduced when adding event tracing to rcutorture. Move the traces to follow the NULL-pointer checks. Signed-off-by: Paul E. McKenney --- kernel/rcutorture.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcutorture.c') diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 5cfa23be43bd..ed1c72bd9c09 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -1000,12 +1000,12 @@ static void rcu_torture_timer(unsigned long unused) rcu_read_lock_bh_held() || rcu_read_lock_sched_held() || srcu_read_lock_held(&srcu_ctl)); - do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu); if (p == NULL) { /* Leave because rcu_torture_writer is not yet underway */ cur_ops->readunlock(idx); return; } + do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu); if (p->rtort_mbtest == 0) atomic_inc(&n_rcu_torture_mberror); spin_lock(&rand_lock); @@ -1063,13 +1063,13 @@ rcu_torture_reader(void *arg) rcu_read_lock_bh_held() || rcu_read_lock_sched_held() || srcu_read_lock_held(&srcu_ctl)); - do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu); if (p == NULL) { /* Wait for rcu_torture_writer to get underway */ cur_ops->readunlock(idx); schedule_timeout_interruptible(HZ); continue; } + do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu); if (p->rtort_mbtest == 0) atomic_inc(&n_rcu_torture_mberror); cur_ops->read_delay(&rand); -- cgit v1.2.3 From 3c1b1ce00d2702d6be9b92233822e560f37ea780 Mon Sep 17 00:00:00 2001 From: Julia Lawall Date: Thu, 2 Feb 2012 07:52:54 -0800 Subject: PTR_ERR should be called before its argument is cleared. The semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @@ expression e,e1; constant c; @@ *e = c ... when != e = e1 when != &e when != true IS_ERR(e) *PTR_ERR(e) // Signed-off-by: Julia Lawall Reported-by: Josh Triplett Signed-off-by: Paul E. McKenney --- kernel/rcutorture.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/rcutorture.c') diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index ed1c72bd9c09..a89b381a8c6e 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -1465,12 +1465,15 @@ rcu_torture_onoff(void *arg) static int __cpuinit rcu_torture_onoff_init(void) { + int ret; + if (onoff_interval <= 0) return 0; onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff"); if (IS_ERR(onoff_task)) { + ret = PTR_ERR(onoff_task); onoff_task = NULL; - return PTR_ERR(onoff_task); + return ret; } return 0; } -- cgit v1.2.3