Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964835AbaFJAgT (ORCPT ); Mon, 9 Jun 2014 20:36:19 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58480 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934391AbaFJAWd (ORCPT ); Mon, 9 Jun 2014 20:22:33 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, Asias He , "Michael S. Tsirkin" , Rusty Russell , Ben Hutchings , Yijing Wang Subject: [PATCH 3.4 45/88] virtio-blk: Call del_gendisk() before disable guest kick Date: Mon, 9 Jun 2014 17:24:55 -0700 Message-Id: <20140610002426.025251054@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140610002424.500996570@linuxfoundation.org> References: <20140610002424.500996570@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 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Asias He commit 02e2b124943648fba0a2ccee5c3656a5653e0151 upstream. del_gendisk() might not return due to failing to remove the /sys/block/vda/serial sysfs entry when another thread (udev) is trying to read it. virtblk_remove() vdev->config->reset() : guest will not kick us through interrupt del_gendisk() device_del() kobject_del(): got stuck, sysfs entry ref count non zero sysfs_open_file(): user space process read /sys/block/vda/serial sysfs_get_active() : got sysfs entry ref count dev_attr_show() virtblk_serial_show() blk_execute_rq() : got stuck, interrupt is disabled request cannot be finished This patch fixes it by calling del_gendisk() before we disable guest's interrupt so that the request sent in virtblk_serial_show() will be finished and del_gendisk() will success. This fixes another race in hot-unplug process. It is save to call del_gendisk(vblk->disk) before flush_work(&vblk->config_work) which might access vblk->disk, because vblk->disk is not freed until put_disk(vblk->disk). Cc: virtualization@lists.linux-foundation.org Cc: kvm@vger.kernel.org Signed-off-by: Asias He Acked-by: Michael S. Tsirkin Signed-off-by: Rusty Russell Signed-off-by: Ben Hutchings Cc: Yijing Wang 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 @@ -581,13 +581,13 @@ static void __devexit virtblk_remove(str vblk->config_enable = false; mutex_unlock(&vblk->config_lock); + del_gendisk(vblk->disk); + /* Stop all the virtqueues. */ vdev->config->reset(vdev); flush_work(&vblk->config_work); - del_gendisk(vblk->disk); - /* Abort requests dispatched to driver. */ spin_lock_irqsave(&vblk->lock, flags); while ((vbr = virtqueue_detach_unused_buf(vblk->vq))) { -- 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/