diff options
author | Asias He <asias@redhat.com> | 2012-05-04 08:22:04 -0400 |
---|---|---|
committer | Rusty Russell <rusty@rustcorp.com.au> | 2012-05-21 22:46:13 -0400 |
commit | b79d866c8b7014a51f611a64c40546109beaf24a (patch) | |
tree | b20a73e60302c74e9a3e0663819cac6c52470c2b /drivers/block | |
parent | 90e03207f468e84258270ad07095ef50f925c17d (diff) |
virtio-blk: Fix hot-unplug race in remove method
If we reset the virtio-blk device before the requests already dispatched
to the virtio-blk driver from the block layer are finised, we will stuck
in blk_cleanup_queue() and the remove will fail.
blk_cleanup_queue() calls blk_drain_queue() to drain all requests queued
before DEAD marking. However it will never success if the device is
already stopped. We'll have q->in_flight[] > 0, so the drain will not
finish.
How to reproduce the race:
1. hot-plug a virtio-blk device
2. keep reading/writing the device in guest
3. hot-unplug while the device is busy serving I/O
Test:
~1000 rounds of hot-plug/hot-unplug test passed with this patch.
Changes in v3:
- Drop blk_abort_queue and blk_abort_request
- Use __blk_end_request_all to complete request dispatched to driver
Changes in v2:
- Drop req_in_flight
- Use virtqueue_detach_unused_buf to get request dispatched to driver
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/block')
-rw-r--r-- | drivers/block/virtio_blk.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 0d39f2f4294a..9d2223bba90c 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c | |||
@@ -583,6 +583,8 @@ static void __devexit virtblk_remove(struct virtio_device *vdev) | |||
583 | { | 583 | { |
584 | struct virtio_blk *vblk = vdev->priv; | 584 | struct virtio_blk *vblk = vdev->priv; |
585 | int index = vblk->index; | 585 | int index = vblk->index; |
586 | struct virtblk_req *vbr; | ||
587 | unsigned long flags; | ||
586 | 588 | ||
587 | /* Prevent config work handler from accessing the device. */ | 589 | /* Prevent config work handler from accessing the device. */ |
588 | mutex_lock(&vblk->config_lock); | 590 | mutex_lock(&vblk->config_lock); |
@@ -598,6 +600,15 @@ static void __devexit virtblk_remove(struct virtio_device *vdev) | |||
598 | flush_work(&vblk->config_work); | 600 | flush_work(&vblk->config_work); |
599 | 601 | ||
600 | del_gendisk(vblk->disk); | 602 | del_gendisk(vblk->disk); |
603 | |||
604 | /* Abort requests dispatched to driver. */ | ||
605 | spin_lock_irqsave(&vblk->lock, flags); | ||
606 | while ((vbr = virtqueue_detach_unused_buf(vblk->vq))) { | ||
607 | __blk_end_request_all(vbr->req, -EIO); | ||
608 | mempool_free(vbr, vblk->pool); | ||
609 | } | ||
610 | spin_unlock_irqrestore(&vblk->lock, flags); | ||
611 | |||
601 | blk_cleanup_queue(vblk->disk->queue); | 612 | blk_cleanup_queue(vblk->disk->queue); |
602 | put_disk(vblk->disk); | 613 | put_disk(vblk->disk); |
603 | mempool_destroy(vblk->pool); | 614 | mempool_destroy(vblk->pool); |