Re: [PATCH] blk-mq: fix race between complete and BLK_EH_RESET_TIMER

On Wed, Apr 11, 2018 at 02:30:07PM -0700, Tejun Heo wrote:

Hello, Ming.

On Thu, Apr 12, 2018 at 04:55:29AM +0800, Ming Lei wrote: ...

...

• spin_lock_irqsave(req->q->queue_lock, flags);
  

• if (blk_mq_rq_state(req) != MQ_RQ_COMPLETE_IN_RESET) {
  

• 	blk_mq_rq_update_aborted_gstate(req, 0);
  

• 	blk_add_timer(req);
  

Nothing prevents the above blk_add_timer() racing against the next recycle instance of the request, so this still leaves a small race window.

OK.

But this small race window can be avoided by running blk_add_timer(req) before blk_mq_rq_update_aborted_gstate(req, 0), can't it?