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rcu: Add duplicate-callback tests to rcutorture

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This commit adds a object_debug option to rcutorture to allow the
debug-object-based checks for duplicate call_rcu() invocations to
be deterministically tested.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
[ paulmck: Banish mid-function ifdef, more or less per Josh Triplett. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
[ paulmck: Improve duplicate-callback test, per Lai Jiangshan. ]
This commit is contained in:
Paul E. McKenney 2013-04-23 17:05:42 -07:00
parent f7f7bac9cb
commit d2818df168
1 changed files with 61 additions and 0 deletions
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61
kernel/rcutorture.c
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@ -66,6 +66,7 @@ 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 n_barrier_cbs; /* Number of callbacks to test RCU barriers. */
static int object_debug; /* Test object-debug double call_rcu()?. */
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. */
@ -100,6 +101,8 @@ module_param(fqs_stutter, int, 0444);
MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
module_param(n_barrier_cbs, int, 0444);
MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
module_param(object_debug, int, 0444);
MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() testing");
module_param(onoff_interval, int, 0444);
MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
module_param(onoff_holdoff, int, 0444);
@ -1934,6 +1937,62 @@ rcu_torture_cleanup(void)
rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
}
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
static void rcu_torture_leak_cb(struct rcu_head *rhp)
{
}
static void rcu_torture_err_cb(struct rcu_head *rhp)
{
/*
* This -might- happen due to race conditions, but is unlikely.
* The scenario that leads to this happening is that the
* first of the pair of duplicate callbacks is queued,
* someone else starts a grace period that includes that
* callback, then the second of the pair must wait for the
* next grace period. Unlikely, but can happen. If it
* does happen, the debug-objects subsystem won't have splatted.
*/
pr_alert("rcutorture: duplicated callback was invoked.\n");
}
#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
/*
* Verify that double-free causes debug-objects to complain, but only
* if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y. Otherwise, say that the test
* cannot be carried out.
*/
static void rcu_test_debug_objects(void)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
struct rcu_head rh1;
struct rcu_head rh2;
init_rcu_head_on_stack(&rh1);
init_rcu_head_on_stack(&rh2);
pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
/* Try to queue the rh2 pair of callbacks for the same grace period. */
preempt_disable(); /* Prevent preemption from interrupting test. */
rcu_read_lock(); /* Make it impossible to finish a grace period. */
call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
local_irq_disable(); /* Make it harder to start a new grace period. */
call_rcu(&rh2, rcu_torture_leak_cb);
call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
local_irq_enable();
rcu_read_unlock();
preempt_enable();
/* Wait for them all to get done so we can safely return. */
rcu_barrier();
pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
destroy_rcu_head_on_stack(&rh1);
destroy_rcu_head_on_stack(&rh2);
#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
}
static int __init
rcu_torture_init(void)
{
@ -2163,6 +2222,8 @@ rcu_torture_init(void)
firsterr = retval;
goto unwind;
}
if (object_debug)
rcu_test_debug_objects();
rcutorture_record_test_transition();
mutex_unlock(&fullstop_mutex);
return 0;