On 27/11/13 11:47, Michael S. Tsirkin wrote:
On Wed, Nov 27, 2013 at 11:32:39AM +0100, Heinz Graalfs wrote:
Code is added to avoid calling blk_cleanup_queue() when the surprize_removal
flag is set due to a disappeared device. It avoid hangs due to incomplete
requests (e.g. in-flight requests). Such requests must be considered as lost.
Ugh. Can't we complete these immediately using detach_unused_buf? If not why?
OK, I will try
If the current remove callback was triggered due to an unregister driver,
and the surprize_removal is not already set (although the actual device
is already gone, e.g. virsh detach), blk_cleanup_queue() would be triggered
resulting in a possible hang. This hang is caused by e.g. 'in-flight' requests
that will never complete. This is a weird situation, and most likely not
'serializable'.
Hmm interesting. Implement some timeout and probe device to make sure
it's still alive?
but there is always some race, isn't it?
Signed-off-by: Heinz Graalfs <graalfs@xxxxxxxxxxxxxxxxxx>
---
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 0f64282..8c05001 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -892,7 +892,8 @@ static void virtblk_remove(struct virtio_device *vdev)
}
del_gendisk(vblk->disk);
- blk_cleanup_queue(vblk->disk->queue);
+ if (!vdev->surprize_removal)
+ blk_cleanup_queue(vblk->disk->queue);
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
--
1.8.3.1
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