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: Rusty Russell <ru...@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <m...@redhat.com>
Cc: virtualizat...@lists.linux-foundation.org
Cc: kvm@vger.kernel.org
Signed-off-by: Asias He <as...@redhat.com>
---
drivers/block/virtio_blk.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 693187d..7d5f5b0 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -584,12 +584,13 @@ 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);
--
1.7.10.1
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
