diff options
| author | Asias He <asias@redhat.com> | 2012-05-25 10:34:47 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-09-12 03:37:33 +0100 |
| commit | 88963fd6c66bf065c6e9c36f1f5de4dff30624a1 (patch) | |
| tree | 3280afd1d677107a8b2cc90795c28770100e7ae2 | |
| parent | e5000b33460e5008a3a189dc2107d274d8096eff (diff) | |
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>
| -rw-r--r-- | drivers/block/virtio_blk.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index cadf9bba1b6b..4f018c495792 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -554,13 +554,13 @@ 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))) { |