On Thu, Jun 22, 2017 at 09:36:52AM +0800, Junxiao Bi wrote: > When ring buf full, hw queue will be stopped. While blkif interrupt consume > request and make free space in ring buf, hw queue will be started again. > But since start queue is protected by spin lock while stop not, that will > cause a race. > > interrupt: process: > blkif_interrupt() blkif_queue_rq() > kick_pending_request_queues_locked() > blk_mq_start_stopped_hw_queues() > clear_bit(BLK_MQ_S_STOPPED, &hctx->state) > blk_mq_stop_hw_queue(hctx) > blk_mq_run_hw_queue(hctx, async) > > If ring buf is made empty in this case, interrupt will never come, then the > hw queue will be stopped forever, all processes waiting for the pending io > in the queue will hung. > > Signed-off-by: Junxiao Bi <junxiao...@oracle.com> > Reviewed-by: Ankur Arora <ankur.a.ar...@oracle.com>
Acked-by: Roger Pau Monné <roger....@citrix.com> Thanks, Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
