diff options
| author | Asias He <asias@redhat.com> | 2012-05-04 20:22:04 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-09-12 03:37:32 +0100 |
| commit | e5000b33460e5008a3a189dc2107d274d8096eff (patch) | |
| tree | 18105aa77de20b11b1c5430d1d2e862a6254f0aa /drivers/block | |
| parent | 788c8de383e3c59df49126f95343eed0cf1733ea (diff) | |
virtio-blk: Fix hot-unplug race in remove method
commit b79d866c8b7014a51f611a64c40546109beaf24a upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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 108ebb43ed51..cadf9bba1b6b 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -546,6 +546,8 @@ static void __devexit virtblk_remove(struct virtio_device *vdev) { 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); @@ -558,6 +560,15 @@ static void __devexit virtblk_remove(struct virtio_device *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))) { + __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); |