From 548095dea63ffc016d39c35b32c628d033638aca Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 9 Oct 2017 11:22:50 -0700 Subject: locking: Remove smp_read_barrier_depends() from queued_spin_lock_slowpath() Queued spinlocks are not used by DEC Alpha, and furthermore operations such as READ_ONCE() and release/relaxed RMW atomics are being changed to imply smp_read_barrier_depends(). This commit therefore removes the now-redundant smp_read_barrier_depends() from queued_spin_lock_slowpath(), and adjusts the comments accordingly. Signed-off-by: Paul E. McKenney Cc: Peter Zijlstra Cc: Ingo Molnar --- kernel/locking/qspinlock.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'kernel/locking') diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index 294294c71ba4..38ece035039e 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -170,7 +170,7 @@ static __always_inline void clear_pending_set_locked(struct qspinlock *lock) * @tail : The new queue tail code word * Return: The previous queue tail code word * - * xchg(lock, tail) + * xchg(lock, tail), which heads an address dependency * * p,*,* -> n,*,* ; prev = xchg(lock, node) */ @@ -409,13 +409,11 @@ queue: if (old & _Q_TAIL_MASK) { prev = decode_tail(old); /* - * The above xchg_tail() is also a load of @lock which generates, - * through decode_tail(), a pointer. - * - * The address dependency matches the RELEASE of xchg_tail() - * such that the access to @prev must happen after. + * The above xchg_tail() is also a load of @lock which + * generates, through decode_tail(), a pointer. The address + * dependency matches the RELEASE of xchg_tail() such that + * the subsequent access to @prev happens after. */ - smp_read_barrier_depends(); WRITE_ONCE(prev->next, node); -- cgit 1.4.1 From cc1321c96f855525fbd847fec130f000daa1bb1f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 16 Oct 2017 11:05:03 -0700 Subject: torture: Reduce #ifdefs for preempt_schedule() This commit adds a torture_preempt_schedule() that is nothingness in !PREEMPT builds and is preempt_schedule() otherwise. Then torture_preempt_schedule() is used to eliminate several ugly #ifdefs, both in rcutorture and in locktorture. Signed-off-by: Paul E. McKenney --- include/linux/torture.h | 6 ++++++ kernel/locking/locktorture.c | 24 ++++++------------------ kernel/rcu/rcutorture.c | 4 +--- 3 files changed, 13 insertions(+), 21 deletions(-) (limited to 'kernel/locking') diff --git a/include/linux/torture.h b/include/linux/torture.h index a45702eb3e7b..907d266aaddc 100644 --- a/include/linux/torture.h +++ b/include/linux/torture.h @@ -96,4 +96,10 @@ void _torture_stop_kthread(char *m, struct task_struct **tp); #define torture_stop_kthread(n, tp) \ _torture_stop_kthread("Stopping " #n " task", &(tp)) +#ifdef CONFIG_PREEMPT +#define torture_preempt_schedule() preempt_schedule() +#else +#define torture_preempt_schedule() +#endif + #endif /* __LINUX_TORTURE_H */ diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index f24582d4dad3..617cea2520b3 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -130,10 +130,8 @@ static void torture_lock_busted_write_delay(struct torture_random_state *trsp) if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * longdelay_ms))) mdelay(longdelay_ms); -#ifdef CONFIG_PREEMPT if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) - preempt_schedule(); /* Allow test to be preempted. */ -#endif + torture_preempt_schedule(); /* Allow test to be preempted. */ } static void torture_lock_busted_write_unlock(void) @@ -179,10 +177,8 @@ static void torture_spin_lock_write_delay(struct torture_random_state *trsp) if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 2 * shortdelay_us))) udelay(shortdelay_us); -#ifdef CONFIG_PREEMPT if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) - preempt_schedule(); /* Allow test to be preempted. */ -#endif + torture_preempt_schedule(); /* Allow test to be preempted. */ } static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock) @@ -352,10 +348,8 @@ static void torture_mutex_delay(struct torture_random_state *trsp) mdelay(longdelay_ms * 5); else mdelay(longdelay_ms / 5); -#ifdef CONFIG_PREEMPT if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) - preempt_schedule(); /* Allow test to be preempted. */ -#endif + torture_preempt_schedule(); /* Allow test to be preempted. */ } static void torture_mutex_unlock(void) __releases(torture_mutex) @@ -507,10 +501,8 @@ static void torture_rtmutex_delay(struct torture_random_state *trsp) if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 2 * shortdelay_us))) udelay(shortdelay_us); -#ifdef CONFIG_PREEMPT if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) - preempt_schedule(); /* Allow test to be preempted. */ -#endif + torture_preempt_schedule(); /* Allow test to be preempted. */ } static void torture_rtmutex_unlock(void) __releases(torture_rtmutex) @@ -547,10 +539,8 @@ static void torture_rwsem_write_delay(struct torture_random_state *trsp) mdelay(longdelay_ms * 10); else mdelay(longdelay_ms / 10); -#ifdef CONFIG_PREEMPT if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) - preempt_schedule(); /* Allow test to be preempted. */ -#endif + torture_preempt_schedule(); /* Allow test to be preempted. */ } static void torture_rwsem_up_write(void) __releases(torture_rwsem) @@ -574,10 +564,8 @@ static void torture_rwsem_read_delay(struct torture_random_state *trsp) mdelay(longdelay_ms * 2); else mdelay(longdelay_ms / 2); -#ifdef CONFIG_PREEMPT if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000))) - preempt_schedule(); /* Allow test to be preempted. */ -#endif + torture_preempt_schedule(); /* Allow test to be preempted. */ } static void torture_rwsem_up_read(void) __releases(torture_rwsem) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 74f6b0146b98..e7d3cce84214 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -315,11 +315,9 @@ static void rcu_read_delay(struct torture_random_state *rrsp) } if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) udelay(shortdelay_us); -#ifdef CONFIG_PREEMPT if (!preempt_count() && !(torture_random(rrsp) % (nrealreaders * 20000))) - preempt_schedule(); /* No QS if preempt_disable() in effect */ -#endif + torture_preempt_schedule(); /* QS only if preemptible. */ } static void rcu_torture_read_unlock(int idx) __releases(RCU) -- cgit 1.4.1 From f2f762608f45353b0b8c37507824f95bb716c3d5 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Mon, 15 May 2017 02:07:22 -0700 Subject: locking/locktorture: Fix rwsem reader_delay We should account for nreader threads, not writers in this callback. Could even trigger a div by 0 if the user explicitly disables writers. Signed-off-by: Davidlohr Bueso Signed-off-by: Paul E. McKenney --- kernel/locking/locktorture.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/locking') diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 617cea2520b3..a307a79e6b0b 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -560,7 +560,7 @@ static void torture_rwsem_read_delay(struct torture_random_state *trsp) /* We want a long delay occasionally to force massive contention. */ if (!(torture_random(trsp) % - (cxt.nrealwriters_stress * 2000 * longdelay_ms))) + (cxt.nrealreaders_stress * 2000 * longdelay_ms))) mdelay(longdelay_ms * 2); else mdelay(longdelay_ms / 2); -- cgit 1.4.1 From 2ce77d16db4240dd2e422fc0a5c26d3e2ec03446 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Mon, 15 May 2017 02:07:23 -0700 Subject: locking/locktorture: Fix num reader/writer corner cases Things can explode for locktorture if the user does combinations of nwriters_stress=0 nreaders_stress=0. Fix this by not assuming we always want to torture writer threads. Reported-by: Jeremy Linton Signed-off-by: Davidlohr Bueso Signed-off-by: Paul E. McKenney Reviewed-by: Jeremy Linton Tested-by: Jeremy Linton --- kernel/locking/locktorture.c | 76 +++++++++++++++++++++++++------------------- 1 file changed, 44 insertions(+), 32 deletions(-) (limited to 'kernel/locking') diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index a307a79e6b0b..2a1fc2a58910 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -703,8 +703,7 @@ static void __torture_print_stats(char *page, { bool fail = 0; int i, n_stress; - long max = 0; - long min = statp[0].n_lock_acquired; + long max = 0, min = statp ? statp[0].n_lock_acquired : 0; long long sum = 0; n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress; @@ -811,7 +810,7 @@ static void lock_torture_cleanup(void) * such, only perform the underlying torture-specific cleanups, * and avoid anything related to locktorture. */ - if (!cxt.lwsa) + if (!cxt.lwsa && !cxt.lrsa) goto end; if (writer_tasks) { @@ -886,6 +885,13 @@ static int __init lock_torture_init(void) firsterr = -EINVAL; goto unwind; } + + if (nwriters_stress == 0 && nreaders_stress == 0) { + pr_alert("lock-torture: must run at least one locking thread\n"); + firsterr = -EINVAL; + goto unwind; + } + if (cxt.cur_ops->init) cxt.cur_ops->init(); @@ -909,17 +915,19 @@ static int __init lock_torture_init(void) #endif /* Initialize the statistics so that each run gets its own numbers. */ + if (nwriters_stress) { + lock_is_write_held = 0; + cxt.lwsa = kmalloc(sizeof(*cxt.lwsa) * cxt.nrealwriters_stress, GFP_KERNEL); + if (cxt.lwsa == NULL) { + VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory"); + firsterr = -ENOMEM; + goto unwind; + } - lock_is_write_held = 0; - cxt.lwsa = kmalloc(sizeof(*cxt.lwsa) * cxt.nrealwriters_stress, GFP_KERNEL); - if (cxt.lwsa == NULL) { - VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory"); - firsterr = -ENOMEM; - goto unwind; - } - for (i = 0; i < cxt.nrealwriters_stress; i++) { - cxt.lwsa[i].n_lock_fail = 0; - cxt.lwsa[i].n_lock_acquired = 0; + for (i = 0; i < cxt.nrealwriters_stress; i++) { + cxt.lwsa[i].n_lock_fail = 0; + cxt.lwsa[i].n_lock_acquired = 0; + } } if (cxt.cur_ops->readlock) { @@ -936,19 +944,21 @@ static int __init lock_torture_init(void) cxt.nrealreaders_stress = cxt.nrealwriters_stress; } - lock_is_read_held = 0; - cxt.lrsa = kmalloc(sizeof(*cxt.lrsa) * cxt.nrealreaders_stress, GFP_KERNEL); - if (cxt.lrsa == NULL) { - VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory"); - firsterr = -ENOMEM; - kfree(cxt.lwsa); - cxt.lwsa = NULL; - goto unwind; - } - - for (i = 0; i < cxt.nrealreaders_stress; i++) { - cxt.lrsa[i].n_lock_fail = 0; - cxt.lrsa[i].n_lock_acquired = 0; + if (nreaders_stress) { + lock_is_read_held = 0; + cxt.lrsa = kmalloc(sizeof(*cxt.lrsa) * cxt.nrealreaders_stress, GFP_KERNEL); + if (cxt.lrsa == NULL) { + VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory"); + firsterr = -ENOMEM; + kfree(cxt.lwsa); + cxt.lwsa = NULL; + goto unwind; + } + + for (i = 0; i < cxt.nrealreaders_stress; i++) { + cxt.lrsa[i].n_lock_fail = 0; + cxt.lrsa[i].n_lock_acquired = 0; + } } } @@ -978,12 +988,14 @@ static int __init lock_torture_init(void) goto unwind; } - writer_tasks = kzalloc(cxt.nrealwriters_stress * sizeof(writer_tasks[0]), - GFP_KERNEL); - if (writer_tasks == NULL) { - VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory"); - firsterr = -ENOMEM; - goto unwind; + if (nwriters_stress) { + writer_tasks = kzalloc(cxt.nrealwriters_stress * sizeof(writer_tasks[0]), + GFP_KERNEL); + if (writer_tasks == NULL) { + VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory"); + firsterr = -ENOMEM; + goto unwind; + } } if (cxt.cur_ops->readlock) { -- cgit 1.4.1 From a2f2577d96ad060b65eb909dd39b57d676754119 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 21 Nov 2017 20:19:17 -0800 Subject: torture: Eliminate torture_runnable and perf_runnable The purpose of torture_runnable is to allow rcutorture and locktorture to be started and stopped via sysfs when they are built into the kernel (as in not compiled as loadable modules). However, the 0444 permissions for both instances of torture_runnable prevent this use case from ever being put into practice. Given that there have been no complaints about this deficiency, it is reasonable to conclude that no one actually makes use of this sysfs capability. The perf_runnable module parameter for rcuperf is in the same situation. This commit therefore removes both torture_runnable instances as well as perf_runnable. Reported-by: Thomas Gleixner Signed-off-by: Paul E. McKenney --- Documentation/admin-guide/kernel-parameters.txt | 9 --------- Documentation/locking/locktorture.txt | 5 ----- include/linux/torture.h | 2 +- kernel/locking/locktorture.c | 6 +----- kernel/rcu/rcuperf.c | 6 +----- kernel/rcu/rcutorture.c | 6 +----- kernel/torture.c | 6 ++---- tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh | 1 - tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh | 1 - .../selftests/rcutorture/configs/rcuperf/ver_functions.sh | 1 - 10 files changed, 6 insertions(+), 37 deletions(-) (limited to 'kernel/locking') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6571fbfdb2a1..66d471f0b92e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2049,9 +2049,6 @@ This tests the locking primitive's ability to transition abruptly to and from idle. - locktorture.torture_runnable= [BOOT] - Start locktorture running at boot time. - locktorture.torture_type= [KNL] Specify the locking implementation to test. @@ -3459,9 +3456,6 @@ the same as for rcuperf.nreaders. N, where N is the number of CPUs - rcuperf.perf_runnable= [BOOT] - Start rcuperf running at boot time. - rcuperf.perf_type= [KNL] Specify the RCU implementation to test. @@ -3595,9 +3589,6 @@ Test RCU's dyntick-idle handling. See also the rcutorture.shuffle_interval parameter. - rcutorture.torture_runnable= [BOOT] - Start rcutorture running at boot time. - rcutorture.torture_type= [KNL] Specify the RCU implementation to test. diff --git a/Documentation/locking/locktorture.txt b/Documentation/locking/locktorture.txt index a2ef3a929bf1..6a8df4cd19bf 100644 --- a/Documentation/locking/locktorture.txt +++ b/Documentation/locking/locktorture.txt @@ -57,11 +57,6 @@ torture_type Type of lock to torture. By default, only spinlocks will o "rwsem_lock": read/write down() and up() semaphore pairs. -torture_runnable Start locktorture at boot time in the case where the - module is built into the kernel, otherwise wait for - torture_runnable to be set via sysfs before starting. - By default it will begin once the module is loaded. - ** Torture-framework (RCU + locking) ** diff --git a/include/linux/torture.h b/include/linux/torture.h index 907d266aaddc..66272862070b 100644 --- a/include/linux/torture.h +++ b/include/linux/torture.h @@ -79,7 +79,7 @@ void stutter_wait(const char *title); int torture_stutter_init(int s); /* Initialization and cleanup. */ -bool torture_init_begin(char *ttype, bool v, int *runnable); +bool torture_init_begin(char *ttype, bool v); void torture_init_end(void); bool torture_cleanup_begin(void); void torture_cleanup_end(void); diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 2a1fc2a58910..6850ffd69125 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -77,10 +77,6 @@ struct lock_stress_stats { long n_lock_acquired; }; -int torture_runnable = IS_ENABLED(MODULE); -module_param(torture_runnable, int, 0444); -MODULE_PARM_DESC(torture_runnable, "Start locktorture at module init"); - /* Forward reference. */ static void lock_torture_cleanup(void); @@ -866,7 +862,7 @@ static int __init lock_torture_init(void) &percpu_rwsem_lock_ops, }; - if (!torture_init_begin(torture_type, verbose, &torture_runnable)) + if (!torture_init_begin(torture_type, verbose)) return -EBUSY; /* Process args and tell the world that the torturer is on the job. */ diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index 1f87a02c3399..d1ebdf9868bb 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -106,10 +106,6 @@ static int rcu_perf_writer_state; #define MAX_MEAS 10000 #define MIN_MEAS 100 -static int perf_runnable = IS_ENABLED(MODULE); -module_param(perf_runnable, int, 0444); -MODULE_PARM_DESC(perf_runnable, "Start rcuperf at boot"); - /* * Operations vector for selecting different types of tests. */ @@ -646,7 +642,7 @@ rcu_perf_init(void) &tasks_ops, }; - if (!torture_init_begin(perf_type, verbose, &perf_runnable)) + if (!torture_init_begin(perf_type, verbose)) return -EBUSY; /* Process args and tell the world that the perf'er is on the job. */ diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 1074ecc3f72f..308e6fdbced8 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -187,10 +187,6 @@ static const char *rcu_torture_writer_state_getname(void) return rcu_torture_writer_state_names[i]; } -static int torture_runnable = IS_ENABLED(MODULE); -module_param(torture_runnable, int, 0444); -MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot"); - #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) #define rcu_can_boost() 1 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */ @@ -1729,7 +1725,7 @@ rcu_torture_init(void) &sched_ops, &tasks_ops, }; - if (!torture_init_begin(torture_type, verbose, &torture_runnable)) + if (!torture_init_begin(torture_type, verbose)) return -EBUSY; /* Process args and tell the world that the torturer is on the job. */ diff --git a/kernel/torture.c b/kernel/torture.c index 3bcbd4fbfe18..572576ad9f58 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -61,7 +61,6 @@ static bool verbose; #define FULLSTOP_RMMOD 2 /* Normal rmmod of torture. */ static int fullstop = FULLSTOP_RMMOD; static DEFINE_MUTEX(fullstop_mutex); -static int *torture_runnable; #ifdef CONFIG_HOTPLUG_CPU @@ -577,7 +576,7 @@ void stutter_wait(const char *title) cond_resched_rcu_qs(); spt = READ_ONCE(stutter_pause_test); - while (spt || (torture_runnable && !READ_ONCE(*torture_runnable))) { + while (spt) { if (spt == 1) { schedule_timeout_interruptible(1); } else if (spt == 2) { @@ -649,7 +648,7 @@ static void torture_stutter_cleanup(void) * The runnable parameter points to a flag that controls whether or not * the test is currently runnable. If there is no such flag, pass in NULL. */ -bool torture_init_begin(char *ttype, bool v, int *runnable) +bool torture_init_begin(char *ttype, bool v) { mutex_lock(&fullstop_mutex); if (torture_type != NULL) { @@ -661,7 +660,6 @@ bool torture_init_begin(char *ttype, bool v, int *runnable) } torture_type = ttype; verbose = v; - torture_runnable = runnable; fullstop = FULLSTOP_DONTSTOP; return true; } diff --git a/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh index 252aae618984..80eb646e1319 100644 --- a/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh +++ b/tools/testing/selftests/rcutorture/configs/lock/ver_functions.sh @@ -38,6 +38,5 @@ per_version_boot_params () { echo $1 `locktorture_param_onoff "$1" "$2"` \ locktorture.stat_interval=15 \ locktorture.shutdown_secs=$3 \ - locktorture.torture_runnable=1 \ locktorture.verbose=1 } diff --git a/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh index ffb85ed786fa..24ec91041957 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh +++ b/tools/testing/selftests/rcutorture/configs/rcu/ver_functions.sh @@ -51,7 +51,6 @@ per_version_boot_params () { `rcutorture_param_n_barrier_cbs "$1"` \ rcutorture.stat_interval=15 \ rcutorture.shutdown_secs=$3 \ - rcutorture.torture_runnable=1 \ rcutorture.test_no_idle_hz=1 \ rcutorture.verbose=1 } diff --git a/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh index 34f2a1b35ee5..b9603115d7c7 100644 --- a/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh +++ b/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh @@ -46,7 +46,6 @@ rcuperf_param_nwriters () { per_version_boot_params () { echo $1 `rcuperf_param_nreaders "$1"` \ `rcuperf_param_nwriters "$1"` \ - rcuperf.perf_runnable=1 \ rcuperf.shutdown=1 \ rcuperf.verbose=1 } -- cgit 1.4.1