From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
Valdis.Kletnieks@vt.edu, dhowells@redhat.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH RFC tip/core/rcu 11/18] rcu: add force_quiescent_state() testing to rcutorture
Date: Tue, 15 Dec 2009 15:02:34 -0800 [thread overview]
Message-ID: <1260918161183-git-send-email-> (raw)
In-Reply-To: <20091215230213.GA9093@linux.vnet.ibm.com>
From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Proposed for 2.6.34, not for inclusion.
Add force_quiescent_state() testing to rcutorture, with a separate
thread that repeatedly invokes force_quiescent_state() in bursts.
This can greatly increase the probability of encountering certain types
of race conditions.
Suggested-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcutiny.h | 12 +++++++
include/linux/rcutree.h | 3 ++
kernel/rcutorture.c | 80 +++++++++++++++++++++++++++++++++++++++++++++-
kernel/rcutree.c | 18 ++++++++++
kernel/rcutree_plugin.h | 19 +++++++++++
5 files changed, 130 insertions(+), 2 deletions(-)
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index c4ba9a7..b524590 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -62,6 +62,18 @@ static inline long rcu_batches_completed_bh(void)
extern int rcu_expedited_torture_stats(char *page);
+static inline void rcu_force_quiescent_state(void)
+{
+}
+
+static inline void rcu_bh_force_quiescent_state(void)
+{
+}
+
+static inline void rcu_sched_force_quiescent_state(void)
+{
+}
+
#define synchronize_rcu synchronize_sched
static inline void synchronize_rcu_expedited(void)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index c93eee5..564a025 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -88,6 +88,9 @@ extern void rcu_check_callbacks(int cpu, int user);
extern long rcu_batches_completed(void);
extern long rcu_batches_completed_bh(void);
extern long rcu_batches_completed_sched(void);
+extern void rcu_force_quiescent_state(void);
+extern void rcu_bh_force_quiescent_state(void);
+extern void rcu_sched_force_quiescent_state(void);
#ifdef CONFIG_NO_HZ
void rcu_enter_nohz(void);
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index a621a67..b4096d3 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -61,6 +61,9 @@ static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
static int stutter = 5; /* Start/stop testing interval (in sec) */
static int irqreader = 1; /* RCU readers from irq (timers). */
+static int fqs_duration = 0; /* Duration of bursts (us), 0 to disable. */
+static int fqs_holdoff = 0; /* Hold time within burst (us). */
+static int fqs_stutter = 3; /* Wait time between bursts (s). */
static char *torture_type = "rcu"; /* What RCU implementation to torture. */
module_param(nreaders, int, 0444);
@@ -79,6 +82,12 @@ module_param(stutter, int, 0444);
MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
module_param(irqreader, int, 0444);
MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
+module_param(fqs_duration, int, 0444);
+MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
+module_param(fqs_holdoff, int, 0444);
+MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
+module_param(fqs_stutter, int, 0444);
+MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
@@ -99,6 +108,7 @@ static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
static struct task_struct *shuffler_task;
static struct task_struct *stutter_task;
+static struct task_struct *fqs_task;
#define RCU_TORTURE_PIPE_LEN 10
@@ -263,6 +273,7 @@ struct rcu_torture_ops {
void (*deferred_free)(struct rcu_torture *p);
void (*sync)(void);
void (*cb_barrier)(void);
+ void (*fqs)(void);
int (*stats)(char *page);
int irq_capable;
char *name;
@@ -347,6 +358,7 @@ static struct rcu_torture_ops rcu_ops = {
.deferred_free = rcu_torture_deferred_free,
.sync = synchronize_rcu,
.cb_barrier = rcu_barrier,
+ .fqs = rcu_force_quiescent_state,
.stats = NULL,
.irq_capable = 1,
.name = "rcu"
@@ -388,6 +400,7 @@ static struct rcu_torture_ops rcu_sync_ops = {
.deferred_free = rcu_sync_torture_deferred_free,
.sync = synchronize_rcu,
.cb_barrier = NULL,
+ .fqs = rcu_force_quiescent_state,
.stats = NULL,
.irq_capable = 1,
.name = "rcu_sync"
@@ -403,6 +416,7 @@ static struct rcu_torture_ops rcu_expedited_ops = {
.deferred_free = rcu_sync_torture_deferred_free,
.sync = synchronize_rcu_expedited,
.cb_barrier = NULL,
+ .fqs = rcu_force_quiescent_state,
.stats = NULL,
.irq_capable = 1,
.name = "rcu_expedited"
@@ -465,6 +479,7 @@ static struct rcu_torture_ops rcu_bh_ops = {
.deferred_free = rcu_bh_torture_deferred_free,
.sync = rcu_bh_torture_synchronize,
.cb_barrier = rcu_barrier_bh,
+ .fqs = rcu_bh_force_quiescent_state,
.stats = NULL,
.irq_capable = 1,
.name = "rcu_bh"
@@ -480,6 +495,7 @@ static struct rcu_torture_ops rcu_bh_sync_ops = {
.deferred_free = rcu_sync_torture_deferred_free,
.sync = rcu_bh_torture_synchronize,
.cb_barrier = NULL,
+ .fqs = rcu_bh_force_quiescent_state,
.stats = NULL,
.irq_capable = 1,
.name = "rcu_bh_sync"
@@ -621,6 +637,7 @@ static struct rcu_torture_ops sched_ops = {
.deferred_free = rcu_sched_torture_deferred_free,
.sync = sched_torture_synchronize,
.cb_barrier = rcu_barrier_sched,
+ .fqs = rcu_sched_force_quiescent_state,
.stats = NULL,
.irq_capable = 1,
.name = "sched"
@@ -636,6 +653,7 @@ static struct rcu_torture_ops sched_sync_ops = {
.deferred_free = rcu_sync_torture_deferred_free,
.sync = sched_torture_synchronize,
.cb_barrier = NULL,
+ .fqs = rcu_sched_force_quiescent_state,
.stats = NULL,
.name = "sched_sync"
};
@@ -650,12 +668,45 @@ static struct rcu_torture_ops sched_expedited_ops = {
.deferred_free = rcu_sync_torture_deferred_free,
.sync = synchronize_sched_expedited,
.cb_barrier = NULL,
+ .fqs = rcu_sched_force_quiescent_state,
.stats = rcu_expedited_torture_stats,
.irq_capable = 1,
.name = "sched_expedited"
};
/*
+ * RCU torture force-quiescent-state kthread. Repeatedly induces
+ * bursts of calls to force_quiescent_state(), increasing the probability
+ * of occurrence of some important types of race conditions.
+ */
+static int
+rcu_torture_fqs(void *arg)
+{
+ unsigned long fqs_resume_time;
+ int fqs_burst_remaining;
+
+ VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
+ do {
+ fqs_resume_time = jiffies + fqs_stutter * HZ;
+ while (jiffies - fqs_resume_time > LONG_MAX) {
+ schedule_timeout_interruptible(1);
+ }
+ fqs_burst_remaining = fqs_duration;
+ while (fqs_burst_remaining > 0) {
+ cur_ops->fqs();
+ udelay(fqs_holdoff);
+ fqs_burst_remaining -= fqs_holdoff;
+ }
+ rcu_stutter_wait("rcu_torture_fqs");
+ } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
+ VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
+ rcutorture_shutdown_absorb("rcu_torture_fqs");
+ while (!kthread_should_stop())
+ schedule_timeout_uninterruptible(1);
+ return 0;
+}
+
+/*
* RCU torture writer kthread. Repeatedly substitutes a new structure
* for that pointed to by rcu_torture_current, freeing the old structure
* after a series of grace periods (the "pipeline").
@@ -1030,10 +1081,11 @@ rcu_torture_print_module_parms(char *tag)
printk(KERN_ALERT "%s" TORTURE_FLAG
"--- %s: nreaders=%d nfakewriters=%d "
"stat_interval=%d verbose=%d test_no_idle_hz=%d "
- "shuffle_interval=%d stutter=%d irqreader=%d\n",
+ "shuffle_interval=%d stutter=%d irqreader=%d "
+ "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
- stutter, irqreader);
+ stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
}
static struct notifier_block rcutorture_nb = {
@@ -1109,6 +1161,12 @@ rcu_torture_cleanup(void)
}
stats_task = NULL;
+ if (fqs_task) {
+ VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
+ kthread_stop(fqs_task);
+ }
+ fqs_task = NULL;
+
/* Wait for all RCU callbacks to fire. */
if (cur_ops->cb_barrier != NULL)
@@ -1154,6 +1212,11 @@ rcu_torture_init(void)
mutex_unlock(&fullstop_mutex);
return -EINVAL;
}
+ if (cur_ops->fqs == NULL && fqs_duration != 0) {
+ printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
+ "fqs_duration, fqs disabled.\n");
+ fqs_duration = 0;
+ }
if (cur_ops->init)
cur_ops->init(); /* no "goto unwind" prior to this point!!! */
@@ -1282,6 +1345,19 @@ rcu_torture_init(void)
goto unwind;
}
}
+ if (fqs_duration < 0)
+ fqs_duration = 0;
+ if (fqs_duration) {
+ /* Create the stutter thread */
+ fqs_task = kthread_run(rcu_torture_fqs, NULL,
+ "rcu_torture_fqs");
+ if (IS_ERR(fqs_task)) {
+ firsterr = PTR_ERR(fqs_task);
+ VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
+ fqs_task = NULL;
+ goto unwind;
+ }
+ }
register_reboot_notifier(&rcutorture_nb);
mutex_unlock(&fullstop_mutex);
return 0;
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 55e8f6e..0a4c328 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -157,6 +157,24 @@ long rcu_batches_completed_bh(void)
EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
/*
+ * Force a quiescent state for RCU BH.
+ */
+void rcu_bh_force_quiescent_state(void)
+{
+ force_quiescent_state(&rcu_bh_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
+
+/*
+ * Force a quiescent state for RCU-sched.
+ */
+void rcu_sched_force_quiescent_state(void)
+{
+ force_quiescent_state(&rcu_sched_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
+
+/*
* Does the CPU have callbacks ready to be invoked?
*/
static int
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 37fbccd..f11ebd4 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -62,6 +62,15 @@ long rcu_batches_completed(void)
EXPORT_SYMBOL_GPL(rcu_batches_completed);
/*
+ * Force a quiescent state for preemptible RCU.
+ */
+void rcu_force_quiescent_state(void)
+{
+ force_quiescent_state(&rcu_preempt_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
+
+/*
* Record a preemptable-RCU quiescent state for the specified CPU. Note
* that this just means that the task currently running on the CPU is
* not in a quiescent state. There might be any number of tasks blocked
@@ -713,6 +722,16 @@ long rcu_batches_completed(void)
EXPORT_SYMBOL_GPL(rcu_batches_completed);
/*
+ * Force a quiescent state for RCU, which, because there is no preemptible
+ * RCU, becomes the same as rcu-sched.
+ */
+void rcu_force_quiescent_state(void)
+{
+ rcu_sched_force_quiescent_state();
+}
+EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
+
+/*
* Because preemptable RCU does not exist, we never have to check for
* CPUs being in quiescent states.
*/
--
1.5.2.5
next prev parent reply other threads:[~2009-12-15 23:15 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-15 23:02 [PATCH RFC tip/core/rcu 0/18] rcu: simplify race conditions, add checking Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 01/18] rcu: adjust force_quiescent_state() locking, step 1 Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 02/18] rcu: adjust force_quiescent_state() locking, step 2 Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 03/18] rcu: prohibit starting new grace periods while forcing quiescent states Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 04/18] rcu: eliminate local variable signaled from force_quiescent_state() Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 05/18] rcu: eliminate local variable lastcomp " Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 06/18] rcu: eliminate second argument of rcu_process_dyntick() Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 07/18] rcu: eliminate rcu_process_dyntick() return value Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 08/18] rcu: remove leg of force_quiescent_state() switch statement Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 09/18] rcu: remove redundant grace-period check Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 10/18] rcu: make force_quiescent_state() start grace period if needed Paul E. McKenney
2009-12-15 23:02 ` Paul E. McKenney [this message]
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 12/18] rcu: make MAINTAINERS file match new RCU reality Paul E. McKenney
2009-12-16 0:53 ` Josh Triplett
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 13/18] rcu: add debug check for too many rcu_read_unlock() Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 14/18] rcu: lockdep check for exiting to user space as RCU reader Paul E. McKenney
2009-12-16 10:24 ` Peter Zijlstra
2009-12-16 15:11 ` Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 15/18] rcu: give different levels of the rcu_node hierarchy distinct lockdep names Paul E. McKenney
2009-12-16 0:59 ` Josh Triplett
2009-12-16 1:59 ` Paul E. McKenney
2009-12-16 10:26 ` Peter Zijlstra
2009-12-16 10:33 ` Peter Zijlstra
2009-12-16 15:13 ` Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 16/18] rcu: make lockdep aware of SRCU read-side critical sections Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 17/18] rcu: Provide different lockdep classes for each flavor of RCU Paul E. McKenney
2009-12-15 23:02 ` [PATCH RFC tip/core/rcu 18/18] rcu: add primitives to check for RCU read-side critical sections Paul E. McKenney
2009-12-16 1:04 ` Josh Triplett
2009-12-16 2:08 ` Paul E. McKenney
2009-12-16 10:31 ` Peter Zijlstra
2009-12-16 15:18 ` Paul E. McKenney
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