This is a note to let you know that I've just added the patch titled
virtio-blk: Reset device after blk_cleanup_queue()
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio-blk-reset-device-after-blk_cleanup_queue.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 95964784565aeac65d1c03fc7b2443f8f7102340 Mon Sep 17 00:00:00 2001
From: Asias He <asias@xxxxxxxxxx>
Date: Fri, 25 May 2012 10:34:48 +0800
Subject: virtio-blk: Reset device after blk_cleanup_queue()
From: Asias He <asias@xxxxxxxxxx>
commit 483001c765af6892b3fc3726576cb42f17d1d6b5 upstream.
blk_cleanup_queue() will call blk_drian_queue() to drain all the
requests before queue DEAD marking. If we reset the device before
blk_cleanup_queue() the drain would fail.
1) if the queue is stopped in do_virtblk_request() because device is
full, the q->request_fn() will not be called.
blk_drain_queue() {
while(true) {
...
if (!list_empty(&q->queue_head))
__blk_run_queue(q) {
if (queue is not stoped)
q->request_fn()
}
...
}
}
Do no reset the device before blk_cleanup_queue() gives the chance to
start the queue in interrupt handler blk_done().
2) In commit b79d866c8b7014a51f611a64c40546109beaf24a, We abort requests
dispatched to driver before blk_cleanup_queue(). There is a race if
requests are dispatched to driver after the abort and before the queue
DEAD mark. To fix this, instead of aborting the requests explicitly, we
can just reset the device after after blk_cleanup_queue so that the
device can complete all the requests before queue DEAD marking in the
drain process.
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Signed-off-by: Asias He <asias@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Yijing Wang <wangyijing@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/virtio_blk.c | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -573,8 +573,6 @@ static void __devexit virtblk_remove(str
{
struct virtio_blk *vblk = vdev->priv;
int index = vblk->index;
- struct virtblk_req *vbr;
- unsigned long flags;
/* Prevent config work handler from accessing the device. */
mutex_lock(&vblk->config_lock);
@@ -582,21 +580,13 @@ static void __devexit virtblk_remove(str
mutex_unlock(&vblk->config_lock);
del_gendisk(vblk->disk);
+ blk_cleanup_queue(vblk->disk->queue);
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
flush_work(&vblk->config_work);
- /* Abort requests dispatched to driver. */
- spin_lock_irqsave(&vblk->lock, flags);
- while ((vbr = virtqueue_detach_unused_buf(vblk->vq))) {
- __blk_end_request_all(vbr->req, -EIO);
- mempool_free(vbr, vblk->pool);
- }
- spin_unlock_irqrestore(&vblk->lock, flags);
-
- blk_cleanup_queue(vblk->disk->queue);
put_disk(vblk->disk);
mempool_destroy(vblk->pool);
vdev->config->del_vqs(vdev);
Patches currently in stable-queue which might be from asias@xxxxxxxxxx are
queue-3.4/virtio-blk-fix-hot-unplug-race-in-remove-method.patch
queue-3.4/virtio-blk-call-del_gendisk-before-disable-guest-kick.patch
queue-3.4/virtio_blk-drop-unused-request-tracking-list.patch
queue-3.4/virtio-blk-reset-device-after-blk_cleanup_queue.patch
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