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Commit f67a3356 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Abstract torture_shutdown_absorb() 



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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org&gt;`>
parent c2884de3

include/linux/torture.h

+15 −0
Original line number Diff line number Diff line
@@ -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)
@@ -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 */

kernel/rcu/rcutorture.c

+18 −39
Original line number Diff line number Diff line
@@ -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;
@@ -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);
@@ -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.

 */
@@ -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);

	}

}
@@ -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. */
@@ -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;
@@ -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;
@@ -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;
@@ -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())
@@ -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;
@@ -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;
@@ -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;
@@ -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;
@@ -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();
@@ -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;

kernel/torture.c

+20 −0
Original line number Diff line number Diff line
@@ -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
@@ -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);