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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2008-12-15 16:13:07 -0800
committerIngo Molnar <mingo@elte.hu>2008-12-17 00:04:40 +0100
commit343e9099c8152daff20e10d6269edec21da44fc0 (patch)
tree1d82d5b90d0c83ab4a5240d0c3c3c74b4e19e227
parent29cbda77a67cf263d636feea65d3bbc9c7de2e24 (diff)
downloadlinux-343e9099c8152daff20e10d6269edec21da44fc0.tar.bz2
rcu: fix rcutorture behavior during reboot
Impact: fix very rare reboot hang Because rcutorture ignored all signals, it does not terminate in response to the signals sent at shutdown time. This can cause strange failures due to its continuing to make use of kernel function too late in the shutdown sequence. This patch therefore adds a shutdown notifier to rcutorture, causing it to shut down in response to a reboot or an orderly shutdown. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/rcutorture.c66
1 files changed, 56 insertions, 10 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 85cb90588a55..b31065522104 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -39,6 +39,7 @@
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
+#include <linux/reboot.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/delay.h>
@@ -108,7 +109,6 @@ struct rcu_torture {
int rtort_mbtest;
};
-static int fullstop = 0; /* stop generating callbacks at test end. */
static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture *rcu_torture_current = NULL;
static long rcu_torture_current_version = 0;
@@ -136,6 +136,30 @@ static int stutter_pause_test = 0;
#endif
int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
+#define FULLSTOP_SIGNALED 1 /* Bail due to signal. */
+#define FULLSTOP_CLEANUP 2 /* Orderly shutdown. */
+static int fullstop; /* stop generating callbacks at test end. */
+DEFINE_MUTEX(fullstop_mutex); /* protect fullstop transitions and */
+ /* spawning of kthreads. */
+
+/*
+ * Detect and respond to a signal-based shutdown.
+ */
+static int
+rcutorture_shutdown_notify(struct notifier_block *unused1,
+ unsigned long unused2, void *unused3)
+{
+ if (fullstop)
+ return NOTIFY_DONE;
+ if (signal_pending(current)) {
+ mutex_lock(&fullstop_mutex);
+ if (!ACCESS_ONCE(fullstop))
+ fullstop = FULLSTOP_SIGNALED;
+ mutex_unlock(&fullstop_mutex);
+ }
+ return NOTIFY_DONE;
+}
+
/*
* Allocate an element from the rcu_tortures pool.
*/
@@ -199,11 +223,12 @@ rcu_random(struct rcu_random_state *rrsp)
static void
rcu_stutter_wait(void)
{
- while (stutter_pause_test || !rcutorture_runnable)
+ while ((stutter_pause_test || !rcutorture_runnable) && !fullstop) {
if (rcutorture_runnable)
schedule_timeout_interruptible(1);
else
schedule_timeout_interruptible(round_jiffies_relative(HZ));
+ }
}
/*
@@ -599,7 +624,7 @@ rcu_torture_writer(void *arg)
rcu_stutter_wait();
} while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
- while (!kthread_should_stop())
+ while (!kthread_should_stop() && fullstop != FULLSTOP_SIGNALED)
schedule_timeout_uninterruptible(1);
return 0;
}
@@ -624,7 +649,7 @@ rcu_torture_fakewriter(void *arg)
} while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
- while (!kthread_should_stop())
+ while (!kthread_should_stop() && fullstop != FULLSTOP_SIGNALED)
schedule_timeout_uninterruptible(1);
return 0;
}
@@ -734,7 +759,7 @@ rcu_torture_reader(void *arg)
VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
if (irqreader && cur_ops->irqcapable)
del_timer_sync(&t);
- while (!kthread_should_stop())
+ while (!kthread_should_stop() && fullstop != FULLSTOP_SIGNALED)
schedule_timeout_uninterruptible(1);
return 0;
}
@@ -831,7 +856,7 @@ rcu_torture_stats(void *arg)
do {
schedule_timeout_interruptible(stat_interval * HZ);
rcu_torture_stats_print();
- } while (!kthread_should_stop());
+ } while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
return 0;
}
@@ -899,7 +924,7 @@ rcu_torture_shuffle(void *arg)
do {
schedule_timeout_interruptible(shuffle_interval * HZ);
rcu_torture_shuffle_tasks();
- } while (!kthread_should_stop());
+ } while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
return 0;
}
@@ -914,10 +939,10 @@ rcu_torture_stutter(void *arg)
do {
schedule_timeout_interruptible(stutter * HZ);
stutter_pause_test = 1;
- if (!kthread_should_stop())
+ if (!kthread_should_stop() && !fullstop)
schedule_timeout_interruptible(stutter * HZ);
stutter_pause_test = 0;
- } while (!kthread_should_stop());
+ } while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
return 0;
}
@@ -934,12 +959,27 @@ rcu_torture_print_module_parms(char *tag)
stutter, irqreader);
}
+static struct notifier_block rcutorture_nb = {
+ .notifier_call = rcutorture_shutdown_notify,
+};
+
static void
rcu_torture_cleanup(void)
{
int i;
- fullstop = 1;
+ mutex_lock(&fullstop_mutex);
+ if (!fullstop) {
+ /* If being signaled, let it happen, then exit. */
+ mutex_unlock(&fullstop_mutex);
+ schedule_timeout_interruptible(10 * HZ);
+ if (cur_ops->cb_barrier != NULL)
+ cur_ops->cb_barrier();
+ return;
+ }
+ fullstop = FULLSTOP_CLEANUP;
+ mutex_unlock(&fullstop_mutex);
+ unregister_reboot_notifier(&rcutorture_nb);
if (stutter_task) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
kthread_stop(stutter_task);
@@ -1015,6 +1055,8 @@ rcu_torture_init(void)
{ &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
&srcu_ops, &sched_ops, &sched_ops_sync, };
+ mutex_lock(&fullstop_mutex);
+
/* Process args and tell the world that the torturer is on the job. */
for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
cur_ops = torture_ops[i];
@@ -1024,6 +1066,7 @@ rcu_torture_init(void)
if (i == ARRAY_SIZE(torture_ops)) {
printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
torture_type);
+ mutex_unlock(&fullstop_mutex);
return (-EINVAL);
}
if (cur_ops->init)
@@ -1146,9 +1189,12 @@ rcu_torture_init(void)
goto unwind;
}
}
+ register_reboot_notifier(&rcutorture_nb);
+ mutex_unlock(&fullstop_mutex);
return 0;
unwind:
+ mutex_unlock(&fullstop_mutex);
rcu_torture_cleanup();
return firsterr;
}