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. Could you please recheck my suggestion? The alternatives proposed are far too risky for a 4.17 consideration, and I'm hoping we can stabilize this behavior in the current release if possible. Thanks, Keith
