On Fri, May 11, 2018 at 04:52:11AM +0800, Ming Lei wrote: > Hi Keith, > > On Tue, May 8, 2018 at 11:30 PM, Keith Busch <keith.busch@xxxxxxxxx> wrote: > > On Sat, Apr 28, 2018 at 11:50:17AM +0800, Ming Lei wrote: > >> This sync may be raced with one timed-out request, which may be handled > >> as BLK_EH_HANDLED or BLK_EH_RESET_TIMER, so the above sync queues can't > >> work reliably. > > > > Ming, > > > > As proposed, that scenario is impossible to encounter. Resetting the > > controller inline with the timeout reaps all the commands, and then > > sets the controller state to RESETTING. While blk-mq may not allow the > > driver to complete those requests, having the driver sync with the queues > > will hold the controller in the reset state until blk-mq is done with > > its timeout work; therefore, it is impossible for the NVMe driver to > > return "BLK_EH_RESET_TIMER", and all commands will be completed through > > nvme_timeout's BLK_EH_HANDLED exactly as desired. > > That isn't true for multiple namespace case, each request queue has its > own timeout work, and all these timeout work can be triggered concurrently. The controller state is most certainly not per queue/namespace. It's global to the controller. Once the reset is triggered, nvme_timeout can only return EH_HANDLED.
