On Fri, Jun 15, 2018 at 10:44 AM, jianchao.wang <jianchao.w.wang@xxxxxxxxxx> wrote: > > > On 06/15/2018 10:22 AM, jianchao.wang wrote: >> Hi Ming >> >> On 06/15/2018 10:17 AM, Ming Lei wrote: >>> On Fri, Jun 15, 2018 at 9:57 AM, Jianchao Wang >>> <jianchao.w.wang@xxxxxxxxxx> wrote: >>>> After f6e7d48 (block: remove BLK_EH_HANDLED), LLDD is responsible >>>> to complete the timed out request, however, for blk-legacy, the >>>> 'complete' is still marked, blk_complete_request will do nothing, >>>> we export __blk_complete_request for LLDD to complete the request >>>> in timeout path. >>>> >>>> Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx> >>>> --- >>>> block/blk-softirq.c | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/block/blk-softirq.c b/block/blk-softirq.c >>>> index 01e2b35..15c1f5e 100644 >>>> --- a/block/blk-softirq.c >>>> +++ b/block/blk-softirq.c >>>> @@ -144,6 +144,7 @@ void __blk_complete_request(struct request *req) >>>> >>>> local_irq_restore(flags); >>>> } >>>> +EXPORT_SYMBOL(__blk_complete_request); >>>> >>>> /** >>>> * blk_complete_request - end I/O on a request >>>> -- >>>> 2.7.4 >>>> >>> >>> Looks non-blk-mq timeout code need to convert to ref-counter >>> based approach too? >> >> IMO, ref-counter is just to fix the blk-mq req life recycle issue. >> It cannot replace the blk_mark_rq_complete which could avoid the race between >> timeout and io completion path. > > The .timeout return BLK_EH_DONE doesn't always mean the request has been completed. > Such as scsi-mid layer, its .timeout callback return BLK_EH_DONE but the timed out > request is still in abort or eh process. What if a completion irq come during that ? For blk-mq, it is avoided by the atomic state change in __blk_mq_complete_request(), that is why I mentioned the question in my last reply. But what if the timed-out request has been freed by EH? Then seems req's ref_counter is still needed for non-mq? Thanks, Ming Lei
