Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964848AbaFIXKG (ORCPT ); Mon, 9 Jun 2014 19:10:06 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56749 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933476AbaFIWpd (ORCPT ); Mon, 9 Jun 2014 18:45:33 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Rusty Russell , Ming Lei , Jens Axboe Subject: [PATCH 3.14 31/78] virtio_blk: fix race between start and stop queue Date: Mon, 9 Jun 2014 15:48:11 -0700 Message-Id: <20140609224814.341955807@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140609224813.282275135@linuxfoundation.org> References: <20140609224813.282275135@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei commit aa0818c6ee8d8e4772725a43550823347bc1ad30 upstream. When there isn't enough vring descriptor for adding to vq, blk-mq will be put as stopped state until some of pending descriptors are completed & freed. Unfortunately, the vq's interrupt may come just before blk-mq's BLK_MQ_S_STOPPED flag is set, so the blk-mq will still be kept as stopped even though lots of descriptors are completed and freed in the interrupt handler. The worst case is that all pending descriptors are freed in the interrupt handler, and the queue is kept as stopped forever. This patch fixes the problem by starting/stopping blk-mq with holding vq_lock. Cc: Jens Axboe Cc: Rusty Russell Signed-off-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/virtio_blk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -144,11 +144,11 @@ static void virtblk_done(struct virtqueu if (unlikely(virtqueue_is_broken(vq))) break; } while (!virtqueue_enable_cb(vq)); - spin_unlock_irqrestore(&vblk->vq_lock, flags); /* In case queue is stopped waiting for more buffers. */ if (req_done) blk_mq_start_stopped_hw_queues(vblk->disk->queue); + spin_unlock_irqrestore(&vblk->vq_lock, flags); } static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) @@ -200,8 +200,8 @@ static int virtio_queue_rq(struct blk_mq spin_lock_irqsave(&vblk->vq_lock, flags); if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) { virtqueue_kick(vblk->vq); - spin_unlock_irqrestore(&vblk->vq_lock, flags); blk_mq_stop_hw_queue(hctx); + spin_unlock_irqrestore(&vblk->vq_lock, flags); return BLK_MQ_RQ_QUEUE_BUSY; } -- 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/