On Wed, Jun 27, 2018 at 01:02:12PM -0700, Bart Van Assche wrote: > Because the hctx lock is not held around the only > blk_mq_tag_wakeup_all() call in the block layer, the wait queue > entry removal in blk_mq_dispatch_wake() is protected by the wait > queue lock only. Since the hctx->dispatch_wait entry can occur on > any of the SBQ_WAIT_QUEUES, the wait queue presence check, adding > .dispatch_wait to a wait queue and removing the wait queue entry > must all be protected by both the hctx lock and the wait queue > lock. Actually we don't need to use hctx->lock for protecting hctx->dispatch_wait, and one new lock of hctx->dispatch_wait_lock is enough, please see the following patch: https://marc.info/?l=linux-block&m=152998658713265&w=2 Then we can avoid to disable irq when acquiring hctx->lock. Thanks, Ming
