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

On Thu, 2018-04-12 at 04:55 +0800, Ming Lei wrote:

+again: switch (ret) { case BLK_EH_HANDLED: __blk_mq_complete_request(req); break; case BLK_EH_RESET_TIMER: [ ... ]

• 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);
  

• } else {
  

• 	blk_mq_rq_update_state(req, MQ_RQ_IN_FLIGHT);
  

• 	ret = BLK_EH_HANDLED;
  

• 	goto again;
  

• }
  

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

Does the above chunk introduce a backwards goto from inside a region around which a spinlock is held to outside that region? Can such a goto result in anything else than a deadlock?

Thanks,

Bart.