From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 12 Jan 2018 15:09:37 +0800 From: Ming Lei To: Mike Snitzer Cc: axboe@kernel.dk, Ming Lei , hare@suse.de, Bart.VanAssche@wdc.com, dm-devel@redhat.com, linux-block@vger.kernel.org Subject: Re: [for-4.16 PATCH v4 2/4] block: use queue_lock when clearing QUEUE_FLAG_REGISTERED in blk_unregister_queue Message-ID: <20180112070936.GB31164@ming.t460p> References: <20180111201417.2042-1-snitzer@redhat.com> <20180111201417.2042-3-snitzer@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180111201417.2042-3-snitzer@redhat.com> List-ID: 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@vger.kernel.org # 4.14+ > Reported-by: Bart Van Assche > Signed-off-by: Mike Snitzer > --- > 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