Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756928AbaFSKKa (ORCPT ); Thu, 19 Jun 2014 06:10:30 -0400 Received: from mail-ve0-f181.google.com ([209.85.128.181]:40442 "EHLO mail-ve0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752125AbaFSKK3 (ORCPT ); Thu, 19 Jun 2014 06:10:29 -0400 MIME-Version: 1.0 In-Reply-To: <1403104872-22236-2-git-send-email-tj@kernel.org> References: <1403104872-22236-1-git-send-email-tj@kernel.org> <1403104872-22236-2-git-send-email-tj@kernel.org> Date: Thu, 19 Jun 2014 18:10:28 +0800 Message-ID: Subject: Re: [PATCH 1/6] blk-mq: make blk_mq_stop_hw_queue() reliably block queue processing From: Ming Lei To: Tejun Heo Cc: Jens Axboe , Linux Kernel Mailing List , Kent Overstreet , "Nicholas A. Bellinger" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 18, 2014 at 11:21 PM, Tejun Heo wrote: > blk_mq_stop_hw_queue() has the following two issues. > > * BLK_MQ_S_STOPPED should be set before canceling the work items; > otherwise, a new instance may proceed beyond STOPPED checking > inbetween. > > * cancel_delayed_work() doesn't do anything to work instance already > executing. Use cancel_delayed_work_sync() to ensure that the > currently in-flight one is finished. > > Signed-off-by: Tejun Heo > Cc: Jens Axboe > Cc: Nicholas A. Bellinger > --- > block/blk-mq.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index e11f5f8..4787c3d 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -862,9 +862,9 @@ EXPORT_SYMBOL(blk_mq_run_queues); > > void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx) > { > - cancel_delayed_work(&hctx->run_work); > - cancel_delayed_work(&hctx->delay_work); > set_bit(BLK_MQ_S_STOPPED, &hctx->state); > + cancel_delayed_work_sync(&hctx->run_work); > + cancel_delayed_work_sync(&hctx->delay_work); The function can be called from atomic context, like virtio-blk. Currently blk_mq_stop_hw_queue() is called in case of queue being busy, so looks it is ok with cancel_delayed_work(). Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/