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md/raid5: Convert prepare_to_wait() to wait_woken() api

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raid5_get_active_stripe() can sleep in various situations and it
is called by make_stripe_request() while inside the
prepare_to_wait()/finish_wait() section. Nested waits like this are
not supported.

This was noticed while making other changes that add different sleeps
to raid5_get_active_stripe() that caused a WARNING with
CONFIG_DEBUG_ATOMIC_SLEEP.

No ill effects have been noticed with the code as is, but theoretically
a nested and here could cause a dead lock so it should be fixed.

To fix this, convert the prepare_to_wait() call to use wake_woken()
which supports nested sleeps.

Link: https://lwn.net/Articles/628628/
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Logan Gunthorpe 2022-07-07 13:15:33 -06:00 committed by Jens Axboe
parent b9f91d80de
commit ee1aa06ba3
1 changed files with 6 additions and 7 deletions
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13
drivers/md/raid5.c
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@ -6044,12 +6044,12 @@ static enum stripe_result make_stripe_request(struct mddev *mddev,
static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
struct r5conf *conf = mddev->private;
sector_t logical_sector;
struct stripe_request_ctx ctx = {};
const int rw = bio_data_dir(bi);
enum stripe_result res;
DEFINE_WAIT(w);
int s, stripe_cnt;
if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
@ -6112,7 +6112,8 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
return true;
}
md_account_bio(mddev, &bi);
prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
add_wait_queue(&conf->wait_for_overlap, &wait);
while (1) {
res = make_stripe_request(mddev, conf, &ctx, logical_sector,
bi);
@ -6135,9 +6136,8 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
ctx.batch_last = NULL;
}
schedule();
prepare_to_wait(&conf->wait_for_overlap, &w,
TASK_UNINTERRUPTIBLE);
wait_woken(&wait, TASK_UNINTERRUPTIBLE,
MAX_SCHEDULE_TIMEOUT);
continue;
}
@ -6148,8 +6148,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
logical_sector = ctx.first_sector +
(s << RAID5_STRIPE_SHIFT(conf));
}
finish_wait(&conf->wait_for_overlap, &w);
remove_wait_queue(&conf->wait_for_overlap, &wait);
if (ctx.batch_last)
raid5_release_stripe(ctx.batch_last);