On 4/12/18 5:59 AM, Ming Lei wrote: > The normal request completion can be done before or during handling > BLK_EH_RESET_TIMER, and this race may cause the request to never be > completed since driver's .timeout() may always return > BLK_EH_RESET_TIMER. > > This issue can't be fixed completely by driver, since the normal > completion can be done between returning .timeout() and handling > BLK_EH_RESET_TIMER. > > This patch fixes the race by introducing rq state of > MQ_RQ_COMPLETE_IN_RESET, and reading/writing rq's state by holding > queue lock, which can be per-request actually, but just not necessary > to introduce one lock for so unusual event. > > Also when .timeout() returns BLK_EH_HANDLED, sync with normal > completion path before completing this timed-out rq finally for > avoiding this rq's state touched by normal completion. I like this approach since it keeps the cost outside of the fast path. And it's fine to reuse the queue lock for this, instead of adding a special lock for something we consider a rare occurrence. >From a quick look this looks sane, but I'll take a closer look tomrrow and add some testing too. -- Jens Axboe
