diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2014-10-31 13:57:30 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-11-04 09:17:44 +0300 |
| commit | cb6538e740d7543cd989128625cf8cac4b471e0a (patch) | |
| tree | c2b2c8d97c12fe06ead2f810471bd6f0317da2d0 /kernel/sched/wait.c | |
| parent | 3427445afd26bd2395f29241319283a93f362cd0 (diff) | |
| download | linux-cb6538e740d7543cd989128625cf8cac4b471e0a.tar.xz | |
sched/wait: Fix a kthread race with wait_woken()
There is a race between kthread_stop() and the new wait_woken() that
can result in a lack of progress.
CPU 0 | CPU 1
|
rfcomm_run() | kthread_stop()
... |
if (!test_bit(KTHREAD_SHOULD_STOP)) |
| set_bit(KTHREAD_SHOULD_STOP)
| wake_up_process()
wait_woken() | wait_for_completion()
set_current_state(INTERRUPTIBLE) |
if (!WQ_FLAG_WOKEN) |
schedule_timeout() |
|
After which both tasks will wait.. forever.
Fix this by having wait_woken() check for kthread_should_stop() but
only for kthreads (obviously).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/wait.c')
| -rw-r--r-- | kernel/sched/wait.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c index 4dae1885db6f..852143a79f36 100644 --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -9,6 +9,7 @@ #include <linux/mm.h> #include <linux/wait.h> #include <linux/hash.h> +#include <linux/kthread.h> void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *key) { @@ -297,6 +298,10 @@ int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void * } EXPORT_SYMBOL(autoremove_wake_function); +static inline bool is_kthread_should_stop(void) +{ + return (current->flags & PF_KTHREAD) && kthread_should_stop(); +} /* * DEFINE_WAIT_FUNC(wait, woken_wake_func); @@ -326,7 +331,7 @@ long wait_woken(wait_queue_t *wait, unsigned mode, long timeout) * woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must * also observe all state before the wakeup. */ - if (!(wait->flags & WQ_FLAG_WOKEN)) + if (!(wait->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop()) timeout = schedule_timeout(timeout); __set_current_state(TASK_RUNNING); |