From 474beb575c03e0e7f1a704ac428916898f81b3cd Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 4 Dec 2017 08:21:04 +1100 Subject: md/raid1,raid10: silence warning about wait-within-wait If you prepare_to_wait() after a previous prepare_to_wait(), but before calling schedule(), you get warning: do not call blocking ops when !TASK_RUNNING; state=2 This is appropriate as it is often a bug. The event that the first prepare_to_wait() expects might wake up the schedule following the second prepare_to_wait(), which could be confusing. However if both prepare_to_wait()s are part of simple wait_event() loops, and if the inner one is rarely called, then there is no problem. The inner loop is too simple to get confused by a stray wakeup, and the outer loop won't spin unduly because the inner doesnt affect it often. This pattern occurs in both raid1.c and raid10.c in the use of flush_pending_writes(). The warning can be silenced by setting current->state to TASK_RUNNING. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid1.c | 11 +++++++++++ drivers/md/raid10.c | 12 ++++++++++++ 2 files changed, 23 insertions(+) (limited to 'drivers') diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 6df398e3a008..b2eae332e1a2 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -815,6 +815,17 @@ static void flush_pending_writes(struct r1conf *conf) bio = bio_list_get(&conf->pending_bio_list); conf->pending_count = 0; spin_unlock_irq(&conf->device_lock); + + /* + * As this is called in a wait_event() loop (see freeze_array), + * current->state might be TASK_UNINTERRUPTIBLE which will + * cause a warning when we prepare to wait again. As it is + * rare that this path is taken, it is perfectly safe to force + * us to go around the wait_event() loop again, so the warning + * is a false-positive. Silence the warning by resetting + * thread state + */ + __set_current_state(TASK_RUNNING); blk_start_plug(&plug); flush_bio_list(conf, bio); blk_finish_plug(&plug); diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index c131835cf008..99c9207899a7 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -900,6 +900,18 @@ static void flush_pending_writes(struct r10conf *conf) bio = bio_list_get(&conf->pending_bio_list); conf->pending_count = 0; spin_unlock_irq(&conf->device_lock); + + /* + * As this is called in a wait_event() loop (see freeze_array), + * current->state might be TASK_UNINTERRUPTIBLE which will + * cause a warning when we prepare to wait again. As it is + * rare that this path is taken, it is perfectly safe to force + * us to go around the wait_event() loop again, so the warning + * is a false-positive. Silence the warning by resetting + * thread state + */ + __set_current_state(TASK_RUNNING); + blk_start_plug(&plug); /* flush any pending bitmap writes to disk * before proceeding w/ I/O */ -- cgit v1.2.3