On Thu, Jan 11, 2018 at 03:14:15PM -0500, Mike Snitzer wrote:
> blk_unregister_queue() must protect against any modifications of
> q->queue_flags (not just those performed in blk-sysfs.c). Therefore
> q->queue_lock needs to be used rather than q->sysfs_lock.
>
> Fixes: e9a823fb34a8b ("block: fix warning when I/O elevator is changed as request_queue is being removed")
> Cc: stable@xxxxxxxxxxxxxxx # 4.14+
> Reported-by: Bart Van Assche <Bart.VanAssche@xxxxxxx>
> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> ---
> block/blk-sysfs.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 870484eaed1f..52f57539f1c7 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -929,9 +929,9 @@ void blk_unregister_queue(struct gendisk *disk)
> if (WARN_ON(!q))
> return;
>
> - mutex_lock(&q->sysfs_lock);
> + spin_lock_irq(q->queue_lock);
> queue_flag_clear_unlocked(QUEUE_FLAG_REGISTERED, q);
> - mutex_unlock(&q->sysfs_lock);
> + spin_unlock_irq(q->queue_lock);
>
> wbt_exit(q);
Hi Mike,
This change may not be correct, since at least e9a823fb34a8b depends
on q->sysfs_lock to sync between testing the flag in __elevator_change()
and clearing it here.
Thanks,
Ming
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