From ee1aa06ba3258686452dab2db2a458310a83d07a Mon Sep 17 00:00:00 2001
From: Logan Gunthorpe <logang@deltatee.com>
Date: Thu, 7 Jul 2022 13:15:33 -0600
Subject: [PATCH] md/raid5: Convert prepare_to_wait() to wait_woken() api
Git-commit: ee1aa06ba3258686452dab2db2a458310a83d07a
Patch-mainline: v6.0-rc1
References: jsc#PED-2766
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>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/raid5.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 2690298bd92b..6a6f7d969198 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -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);
--
2.35.3