[1/3] dm-delay: fix workqueue delay_timer race

Commit Message

Benjamin Marzinski May 7, 2024, 9:16 p.m. UTC

delay_timer could be pending when delay_dtr() is called. It needs to be
shut down before kdelayd_wq is destroyed, so it won't try queueing more
work to kdelayd_wq while that's getting destroyed.

Also the del_timer_sync() call in delay_presuspend() doesn't protect
against the timer getting immediately rearmed by the queued call to
flush_delayed_bios(), but there's no real harm if that does happen.
timer_delete() is less work, and is basically just as likely to stop a
pointless call to flush_delayed_bios().

Fixes: 26b9f228703f ("dm: delay target")
Signed-off-by: Benjamin Marzinski <[e-mail]>
---
 drivers/md/dm-delay.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index 1c424983c042..584e3b10802d 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -154,8 +154,10 @@  static void delay_dtr(struct dm_target *ti)
 {
 	struct delay_c *dc = ti->private;
 
-	if (dc->kdelayd_wq)
+	if (dc->kdelayd_wq) {
+		timer_shutdown_sync(&dc->delay_timer);
 		destroy_workqueue(dc->kdelayd_wq);
+	}
 
 	if (dc->read.dev)
 		dm_put_device(ti, dc->read.dev);
@@ -334,7 +336,7 @@  static void delay_presuspend(struct dm_target *ti)
 	mutex_unlock(&delayed_bios_lock);
 
 	if (!delay_is_fast(dc))
-		del_timer_sync(&dc->delay_timer);
+		timer_delete(&dc->delay_timer);
 	flush_delayed_bios(dc, true);
 }