On Wed, 2018-01-24 at 00:59 +0800, Ming Lei wrote: > How is that enough to fix the IO hang when driver returns STS_RESOURCE > and the queue is idle? If you want to follow previous dm-rq's way of > call blk_mq_delay_run_hw_queue() in .queue_rq(), the same trick need > to be applied to other drivers too, right? > > Unfortunately most of STS_RESOURCE don't use this trick, but they need > to be handled. > > The patch of 'blk-mq: introduce BLK_STS_DEV_RESOURCE' can fix all these > cases. The goal of my proposal was to address the race between running the queue and adding requests back to the dispatch queue only. Regarding the I/O hangs that can occur if a block driver returns BLK_STS_RESOURCE: since all of these can be addressed by inserting blk_mq_delay_run_hw_queue() calls in the affected block drivers I prefer to modify the block drivers instead of making the blk-mq core even more complicated. Thanks, Bart.
