Re: [PATCH] Use list_splice for blk_abort_queue

Jens Axboe
2009-02-27T11:40:59Z

On Fri, Feb 27 2009, Hannes Reinecke wrote:
>
> blk_abort_queue takes the queue_lock with spinlock_irqsave and walks
> the timer_list with list_for_each_entry_safe. Since a path to a SCSI
> device just failed, the rport state is FC_PORTSTATE_BLOCKED. This
> rport state triggers blk_add_timer(), which in turn calls
> list_add_tail() to move the request to the end of timer_list. Thus,
> the list_for_each_XXX loop never reaches the end of the timer_list.
> By using list_splice_init() we're breaking the loop and process only
> the requests present on the timeout_list when blk_abort_queue() is
> called.
>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Tested-by: Christof Schmitt <christof.schmitt@de.ibm.com>
> ---
> block/blk-timeout.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/block/blk-timeout.c b/block/blk-timeout.c
> index a095353..67bcc3f 100644
> --- a/block/blk-timeout.c
> +++ b/block/blk-timeout.c
> @@ -209,12 +209,15 @@ void blk_abort_queue(struct request_queue *q)
> {
> unsigned long flags;
> struct request *rq, *tmp;
> + LIST_HEAD(list);
>
> spin_lock_irqsave(q->queue_lock, flags);
>
> elv_abort_queue(q);
>
> - list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
> + list_splice_init(&q->timeout_list, &list);
> +
> + list_for_each_entry_safe(rq, tmp, &list, timeout_list)
> blk_abort_request(rq);
>
> spin_unlock_irqrestore(q->queue_lock, flags);
> --
> 1.5.3.2
>

Hannes, this fix has been in mainline for about 10 days.

--
Jens Axboe