rcutorture: Fix rcutorture shutdown races

Not all of the rcutorture kthreads waited for kthread_should_stop()
before returning from their top-level functions, and none of them
used torture_shutdown_absorb() properly.  These problems can result in
segfaults and hangs at shutdown time, and some recent changes perturbed
timing sufficiently to make them much more probable.  This commit
therefore creates a torture_kthread_stopping() function that does the
proper kthread shutdown dance in one centralized location.

Accommodate this grouping by making VERBOSE_TOROUT_STRING() capable of
taking a non-const string as its argument, which allows the new
torture_kthread_stopping() to pass its "title" argument directly to
the updated version of VERBOSE_TOROUT_STRING().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2014-01-31 17:37:28 -08:00
parent 14562d1cf1
commit 7fafaac5b9
3 changed files with 35 additions and 33 deletions

View File

@ -45,7 +45,7 @@
#define TOROUT_STRING(s) \
pr_alert("%s" TORTURE_FLAG s "\n", torture_type)
#define VERBOSE_TOROUT_STRING(s) \
do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
do { if (verbose) pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s); } while (0)
#define VERBOSE_TOROUT_ERRSTRING(s) \
do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
@ -88,5 +88,6 @@ void torture_init_end(void);
bool torture_cleanup(void);
bool torture_must_stop(void);
bool torture_must_stop_irq(void);
void torture_kthread_stopping(char *title);
#endif /* __LINUX_TORTURE_H */

View File

@ -602,12 +602,13 @@ checkwait: stutter_wait("rcu_torture_boost");
} while (!torture_must_stop());
/* Clean up and exit. */
VERBOSE_TOROUT_STRING("rcu_torture_boost task stopping");
while (!kthread_should_stop() || rbi.inflight) {
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. */
destroy_rcu_head_on_stack(&rbi.rcu);
torture_kthread_stopping("rcu_torture_boost");
return 0;
}
@ -638,10 +639,7 @@ rcu_torture_fqs(void *arg)
}
stutter_wait("rcu_torture_fqs");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_fqs task stopping");
torture_shutdown_absorb("rcu_torture_fqs");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
torture_kthread_stopping("rcu_torture_fqs");
return 0;
}
@ -710,10 +708,7 @@ rcu_torture_writer(void *arg)
rcutorture_record_progress(++rcu_torture_current_version);
stutter_wait("rcu_torture_writer");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_writer task stopping");
torture_shutdown_absorb("rcu_torture_writer");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
torture_kthread_stopping("rcu_torture_writer");
return 0;
}
@ -748,10 +743,7 @@ rcu_torture_fakewriter(void *arg)
stutter_wait("rcu_torture_fakewriter");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task stopping");
torture_shutdown_absorb("rcu_torture_fakewriter");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
torture_kthread_stopping("rcu_torture_fakewriter");
return 0;
}
@ -892,12 +884,9 @@ rcu_torture_reader(void *arg)
schedule();
stutter_wait("rcu_torture_reader");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_reader task stopping");
torture_shutdown_absorb("rcu_torture_reader");
if (irqreader && cur_ops->irq_capable)
del_timer_sync(&t);
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
torture_kthread_stopping("rcu_torture_reader");
return 0;
}
@ -1010,7 +999,7 @@ rcu_torture_stats(void *arg)
rcu_torture_stats_print();
torture_shutdown_absorb("rcu_torture_stats");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_stats task stopping");
torture_kthread_stopping("rcu_torture_stats");
return 0;
}
@ -1171,12 +1160,9 @@ static int rcu_torture_barrier_cbs(void *arg)
if (atomic_dec_and_test(&barrier_cbs_count))
wake_up(&barrier_wq);
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task stopping");
torture_shutdown_absorb("rcu_torture_barrier_cbs");
while (!kthread_should_stop())
schedule_timeout_interruptible(1);
cur_ops->cb_barrier();
destroy_rcu_head_on_stack(&rcu);
torture_kthread_stopping("rcu_torture_barrier_cbs");
return 0;
}
@ -1207,10 +1193,7 @@ static int rcu_torture_barrier(void *arg)
n_barrier_successes++;
schedule_timeout_interruptible(HZ / 10);
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("rcu_torture_barrier task stopping");
torture_shutdown_absorb("rcu_torture_barrier");
while (!kthread_should_stop())
schedule_timeout_interruptible(1);
torture_kthread_stopping("rcu_torture_barrier");
return 0;
}

View File

@ -169,7 +169,7 @@ torture_onoff(void *arg)
}
schedule_timeout_interruptible(onoff_interval);
}
VERBOSE_TOROUT_STRING("torture_onoff task stopping");
torture_kthread_stopping("torture_onoff");
return 0;
}
@ -370,7 +370,7 @@ static int torture_shuffle(void *arg)
torture_shuffle_tasks();
torture_shutdown_absorb("torture_shuffle");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("torture_shuffle task stopping");
torture_kthread_stopping("torture_shuffle");
return 0;
}
@ -465,7 +465,7 @@ static int torture_shutdown(void *arg)
jiffies_snap = jiffies;
}
if (torture_must_stop()) {
VERBOSE_TOROUT_STRING("torture_shutdown task stopping");
torture_kthread_stopping("torture_shutdown");
return 0;
}
@ -583,7 +583,7 @@ static int torture_stutter(void *arg)
ACCESS_ONCE(stutter_pause_test) = 0;
torture_shutdown_absorb("torture_stutter");
} while (!torture_must_stop());
VERBOSE_TOROUT_STRING("torture_stutter task stopping");
torture_kthread_stopping("torture_stutter");
return 0;
}
@ -696,3 +696,21 @@ bool torture_must_stop_irq(void)
return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
}
EXPORT_SYMBOL_GPL(torture_must_stop_irq);
/*
* Each kthread must wait for kthread_should_stop() before returning from
* its top-level function, otherwise segfaults ensue. This function
* prints a "stopping" message and waits for kthread_should_stop(), and
* should be called from all torture kthreads immediately prior to
* returning.
*/
void torture_kthread_stopping(char *title)
{
if (verbose)
VERBOSE_TOROUT_STRING(title);
while (!kthread_should_stop()) {
torture_shutdown_absorb(title);
schedule_timeout_uninterruptible(1);
}
}
EXPORT_SYMBOL_GPL(torture_kthread_stopping);