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authorAsias He <asias@redhat.com>2012-05-25 10:34:47 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-11 12:04:17 -0700
commitaf6e24de4b787c77070bbaa2d0cd8e479f1db2d7 (patch)
treecadfadd2528e9e31ebb401d89cce6ab3a299da25
parentf515bcabb5e4514126ab1635c215256cce4163a2 (diff)
downloadlinux-linaro-stable-af6e24de4b787c77070bbaa2d0cd8e479f1db2d7.tar.gz
virtio-blk: Call del_gendisk() before disable guest kick
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 <asias@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Yijing Wang <wangyijing@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/block/virtio_blk.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 4b8c77322c69..4d5108c6b64e 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -581,13 +581,13 @@ static void __devexit virtblk_remove(struct virtio_device *vdev)
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))) {