ACK: [SRU][Xenial][PATCH 1/1] block: Fix a race between blk_cleanup_queue() and timeout handling

[Stefan Bader]

On 20.09.2018 12:01, Joseph Salisbury wrote:
> From: Bart Van Assche <bart.vanassche at wdc.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1791790
> 
> Make sure that if the timeout timer fires after a queue has been
> marked "dying" that the affected requests are finished.
> 
> Reported-by: chenxiang (M) <chenxiang66 at hisilicon.com>
> Fixes: commit 287922eb0b18 ("block: defer timeouts to a workqueue")
> Signed-off-by: Bart Van Assche <bart.vanassche at wdc.com>
> Tested-by: chenxiang (M) <chenxiang66 at hisilicon.com>
> Cc: Christoph Hellwig <hch at lst.de>
> Cc: Keith Busch <keith.busch at intel.com>
> Cc: Hannes Reinecke <hare at suse.com>
> Cc: Ming Lei <ming.lei at redhat.com>
> Cc: Johannes Thumshirn <jthumshirn at suse.de>
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Jens Axboe <axboe at kernel.dk>
> (cherry picked from commit 4e9b6f20828ac880dbc1fa2fdbafae779473d1af)
> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  block/blk-core.c    | 2 ++
>  block/blk-timeout.c | 3 ---
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index be184a8..13c1e5c 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -266,6 +266,7 @@ EXPORT_SYMBOL(blk_stop_queue);
>  void blk_sync_queue(struct request_queue *q)
>  {
>  	del_timer_sync(&q->timeout);
> +	cancel_work_sync(&q->timeout_work);
>  
>  	if (q->mq_ops) {
>  		struct blk_mq_hw_ctx *hctx;
> @@ -701,6 +702,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
>  	setup_timer(&q->backing_dev_info->laptop_mode_wb_timer,
>  		    laptop_mode_timer_fn, (unsigned long) q);
>  	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
> +	INIT_WORK(&q->timeout_work, NULL);
>  	INIT_LIST_HEAD(&q->queue_head);
>  	INIT_LIST_HEAD(&q->timeout_list);
>  	INIT_LIST_HEAD(&q->icq_list);
> diff --git a/block/blk-timeout.c b/block/blk-timeout.c
> index 7c176f6..aedd128 100644
> --- a/block/blk-timeout.c
> +++ b/block/blk-timeout.c
> @@ -135,8 +135,6 @@ void blk_timeout_work(struct work_struct *work)
>  	struct request *rq, *tmp;
>  	int next_set = 0;
>  
> -	if (blk_queue_enter(q, true))
> -		return;
>  	spin_lock_irqsave(q->queue_lock, flags);
>  
>  	list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
> @@ -146,7 +144,6 @@ void blk_timeout_work(struct work_struct *work)
>  		mod_timer(&q->timeout, round_jiffies_up(next));
>  
>  	spin_unlock_irqrestore(q->queue_lock, flags);
> -	blk_queue_exit(q);
>  }
>  
>  /**
> 


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