[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen-blkfront: fix mq start/stop race
On 07/19/2017 10:08 PM, Konrad Rzeszutek Wilk wrote: > On Wed, Jul 19, 2017 at 03:51:48PM +0800, Junxiao Bi wrote: >> Hi Konrad, >> >> On 07/19/2017 03:37 PM, Roger Pau Monné wrote: >>> On Wed, Jul 19, 2017 at 09:19:49AM +0800, Junxiao Bi wrote: >>>> Hi Roger, >>>> >>>> On 06/23/2017 08:57 PM, Roger Pau Monné wrote: >>>>> 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.bi@xxxxxxxxxx> >>>>>> Reviewed-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx> >>>>> >>>>> Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> >>>> Looks patch not in mainline. Can you please help merge it? >>> >>> I'm afraid this needs to be done by Konrad or one of the Linux >>> maintainers, I don't have an account on kernel.org in order to send >>> pull requests to Jens. >> Can you pls help merge it? > > Could you kindly repost it with the updated tags _and_ against Linus's latest > branch? Sure, v2 sent. Please check. Thanks, Junxiao. > > I get: > [konrad@char linux]$ git am -s < /tmp/a > Applying: xen-blkfront: fix mq start/stop race > error: patch failed: drivers/block/xen-blkfront.c:912 > error: drivers/block/xen-blkfront.c: patch does not apply > Patch failed at 0001 xen-blkfront: fix mq start/stop race > The copy of the patch that failed is found in: .git/rebase-apply/patch > When you have resolved this problem, run "git am --continue". > If you prefer to skip this patch, run "git am --skip" instead. > To restore the original branch and stop patching, run "git am --abort". > > >> >> Thanks, >> Junxiao. >>> >>> Roger. >>> >> _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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