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rcutorture: Abstract torture_shutdown_absorb()
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Because handling races between rmmod and normal shutdown is not specific
to rcutorture, this commit renames rcutorture_shutdown_absorb() to
torture_shutdown_absorb() and pulls it out into then kernel/torture.c
module.  This implies pulling the fullstop mechanism into kernel/torture.c
as well.

The exporting of fullstop and fullstop_mutex is ugly and must die.
And it does in fact die in later commits that introduce higher-level
APIs that encapsulate both of these variables.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>`
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paulmck committed Feb 23, 2014
1 parent c2884de commit f67a335
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Showing 3 changed files with 53 additions and 39 deletions.
15 changes: 15 additions & 0 deletions include/linux/torture.h
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,18 @@
module_param(name, type, 0444); \
MODULE_PARM_DESC(name, msg);

/* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
#define FULLSTOP_DONTSTOP 0 /* Normal operation. */
#define FULLSTOP_SHUTDOWN 1 /* System shutdown with rcutorture running. */
#define FULLSTOP_RMMOD 2 /* Normal rmmod of rcutorture. */
extern int fullstop;
/* Protect fullstop transitions and spawning of kthreads. */
extern struct mutex fullstop_mutex;

/* Common module parameters. */
extern char *torture_type;
extern bool verbose;

#define TORTURE_FLAG "-torture:"
#define TOROUT_STRING(s) \
pr_alert("%s" TORTURE_FLAG s "\n", torture_type)
Expand All @@ -57,4 +69,7 @@ struct torture_random_state {
#define DEFINE_TORTURE_RANDOM(name) struct torture_random_state name = { 0, 0 }
unsigned long torture_random(struct torture_random_state *trsp);

/* Shutdown task absorption, for when the tasks cannot safely be killed. */
void torture_shutdown_absorb(const char *title);

#endif /* __LINUX_TORTURE_H */
57 changes: 18 additions & 39 deletions kernel/rcu/rcutorture.c
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Original file line number Diff line number Diff line change
Expand Up @@ -91,11 +91,15 @@ torture_param(int, test_boost_interval, 7,
"Interval between boost tests, seconds.");
torture_param(bool, test_no_idle_hz, true,
"Test support for tickless idle CPUs");
torture_param(bool, verbose, false, "Enable verbose debugging printk()s");

static char *torture_type = "rcu";
char *torture_type = "rcu";
EXPORT_SYMBOL_GPL(torture_type);
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
bool verbose;
EXPORT_SYMBOL_GPL(verbose);
module_param(verbose, bool, 0444);
MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");

static int nrealreaders;
static struct task_struct *writer_task;
Expand Down Expand Up @@ -200,17 +204,6 @@ static atomic_t barrier_cbs_invoked; /* Barrier callbacks invoked. */
static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);

/* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */

#define FULLSTOP_DONTSTOP 0 /* Normal operation. */
#define FULLSTOP_SHUTDOWN 1 /* System shutdown with rcutorture running. */
#define FULLSTOP_RMMOD 2 /* Normal rmmod of rcutorture. */
static int fullstop = FULLSTOP_RMMOD;
/*
* Protect fullstop transitions and spawning of kthreads.
*/
static DEFINE_MUTEX(fullstop_mutex);

/* Forward reference. */
static void rcu_torture_cleanup(void);

Expand All @@ -231,20 +224,6 @@ rcutorture_shutdown_notify(struct notifier_block *unused1,
return NOTIFY_DONE;
}

/*
* Absorb kthreads into a kernel function that won't return, so that
* they won't ever access module text or data again.
*/
static void rcutorture_shutdown_absorb(const char *title)
{
if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
pr_notice(
"rcutorture thread %s parking due to system shutdown\n",
title);
schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
}
}

/*
* Allocate an element from the rcu_tortures pool.
*/
Expand Down Expand Up @@ -286,7 +265,7 @@ rcu_stutter_wait(const char *title)
schedule_timeout_interruptible(1);
else
schedule_timeout_interruptible(round_jiffies_relative(HZ));
rcutorture_shutdown_absorb(title);
torture_shutdown_absorb(title);
}
}

Expand Down Expand Up @@ -681,7 +660,7 @@ checkwait: rcu_stutter_wait("rcu_torture_boost");

/* Clean up and exit. */
VERBOSE_TOROUT_STRING("rcu_torture_boost task stopping");
rcutorture_shutdown_absorb("rcu_torture_boost");
torture_shutdown_absorb("rcu_torture_boost");
while (!kthread_should_stop() || rbi.inflight)
schedule_timeout_uninterruptible(1);
smp_mb(); /* order accesses to ->inflight before stack-frame death. */
Expand Down Expand Up @@ -717,7 +696,7 @@ rcu_torture_fqs(void *arg)
rcu_stutter_wait("rcu_torture_fqs");
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
VERBOSE_TOROUT_STRING("rcu_torture_fqs task stopping");
rcutorture_shutdown_absorb("rcu_torture_fqs");
torture_shutdown_absorb("rcu_torture_fqs");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
Expand Down Expand Up @@ -789,7 +768,7 @@ rcu_torture_writer(void *arg)
rcu_stutter_wait("rcu_torture_writer");
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
VERBOSE_TOROUT_STRING("rcu_torture_writer task stopping");
rcutorture_shutdown_absorb("rcu_torture_writer");
torture_shutdown_absorb("rcu_torture_writer");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
Expand Down Expand Up @@ -827,7 +806,7 @@ rcu_torture_fakewriter(void *arg)
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);

VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task stopping");
rcutorture_shutdown_absorb("rcu_torture_fakewriter");
torture_shutdown_absorb("rcu_torture_fakewriter");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
Expand Down Expand Up @@ -971,7 +950,7 @@ rcu_torture_reader(void *arg)
rcu_stutter_wait("rcu_torture_reader");
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
VERBOSE_TOROUT_STRING("rcu_torture_reader task stopping");
rcutorture_shutdown_absorb("rcu_torture_reader");
torture_shutdown_absorb("rcu_torture_reader");
if (irqreader && cur_ops->irq_capable)
del_timer_sync(&t);
while (!kthread_should_stop())
Expand Down Expand Up @@ -1095,7 +1074,7 @@ rcu_torture_stats(void *arg)
do {
schedule_timeout_interruptible(stat_interval * HZ);
rcu_torture_stats_print();
rcutorture_shutdown_absorb("rcu_torture_stats");
torture_shutdown_absorb("rcu_torture_stats");
} while (!kthread_should_stop());
VERBOSE_TOROUT_STRING("rcu_torture_stats task stopping");
return 0;
Expand Down Expand Up @@ -1179,7 +1158,7 @@ rcu_torture_shuffle(void *arg)
do {
schedule_timeout_interruptible(shuffle_interval * HZ);
rcu_torture_shuffle_tasks();
rcutorture_shutdown_absorb("rcu_torture_shuffle");
torture_shutdown_absorb("rcu_torture_shuffle");
} while (!kthread_should_stop());
VERBOSE_TOROUT_STRING("rcu_torture_shuffle task stopping");
return 0;
Expand All @@ -1198,7 +1177,7 @@ rcu_torture_stutter(void *arg)
if (!kthread_should_stop())
schedule_timeout_interruptible(stutter * HZ);
stutter_pause_test = 0;
rcutorture_shutdown_absorb("rcu_torture_stutter");
torture_shutdown_absorb("rcu_torture_stutter");
} while (!kthread_should_stop());
VERBOSE_TOROUT_STRING("rcu_torture_stutter task stopping");
return 0;
Expand Down Expand Up @@ -1470,7 +1449,7 @@ static int rcu_torture_stall(void *args)
rcu_read_unlock();
pr_alert("rcu_torture_stall end.\n");
}
rcutorture_shutdown_absorb("rcu_torture_stall");
torture_shutdown_absorb("rcu_torture_stall");
while (!kthread_should_stop())
schedule_timeout_interruptible(10 * HZ);
return 0;
Expand Down Expand Up @@ -1534,7 +1513,7 @@ static int rcu_torture_barrier_cbs(void *arg)
wake_up(&barrier_wq);
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task stopping");
rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
torture_shutdown_absorb("rcu_torture_barrier_cbs");
while (!kthread_should_stop())
schedule_timeout_interruptible(1);
cur_ops->cb_barrier();
Expand Down Expand Up @@ -1571,7 +1550,7 @@ static int rcu_torture_barrier(void *arg)
schedule_timeout_interruptible(HZ / 10);
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
VERBOSE_TOROUT_STRING("rcu_torture_barrier task stopping");
rcutorture_shutdown_absorb("rcu_torture_barrier");
torture_shutdown_absorb("rcu_torture_barrier");
while (!kthread_should_stop())
schedule_timeout_interruptible(1);
return 0;
Expand Down
20 changes: 20 additions & 0 deletions kernel/torture.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,11 @@
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");

int fullstop = FULLSTOP_RMMOD;
EXPORT_SYMBOL_GPL(fullstop);
DEFINE_MUTEX(fullstop_mutex);
EXPORT_SYMBOL_GPL(fullstop_mutex);

#define TORTURE_RANDOM_MULT 39916801 /* prime */
#define TORTURE_RANDOM_ADD 479001701 /* prime */
#define TORTURE_RANDOM_REFRESH 10000
Expand All @@ -69,3 +74,18 @@ torture_random(struct torture_random_state *trsp)
return swahw32(trsp->trs_state);
}
EXPORT_SYMBOL_GPL(torture_random);

/*
* Absorb kthreads into a kernel function that won't return, so that
* they won't ever access module text or data again.
*/
void torture_shutdown_absorb(const char *title)
{
while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
pr_notice(
"torture thread %s parking due to system shutdown\n",
title);
schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
}
}
EXPORT_SYMBOL_GPL(torture_shutdown_absorb);

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