[PATCH 3.13 180/212] virtio_blk: don't crash, report error if virtqueue is broken.

Kamal Mostafa
2014-06-17T21:44:34Z

From: Rusty Russell <rusty@rustcorp.com.au>

commit 5261b85e586afe6ebe54e16e0a8acc32fc6d4902 upstream.

A bad implementation of virtio might cause us to mark the virtqueue
broken: we'll dev_err() in that case, and the device is useless, but
let's not BUG_ON().

ENOMEM or ENOSPC implies the ring is full, and we should try again
later (-ENOMEM is documented to happen, but doesn't, as we fall
through to ENOSPC).

EIO means it's broken.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/block/virtio_blk.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 6a680d4..704d6c8 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -158,6 +158,7 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
unsigned long flags;
unsigned int num;
const bool last = (req->cmd_flags & REQ_END) != 0;
+ int err;

BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);

@@ -198,11 +199,16 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
}

spin_lock_irqsave(&vblk->vq_lock, flags);
- if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) {
+ err = __virtblk_add_req(vblk->vq, vbr, vbr->sg, num);
+ if (err) {
virtqueue_kick(vblk->vq);
spin_unlock_irqrestore(&vblk->vq_lock, flags);
blk_mq_stop_hw_queue(hctx);
- return BLK_MQ_RQ_QUEUE_BUSY;
+ /* Out of mem doesn't actually happen, since we fall back
+ * to direct descriptors */
+ if (err == -ENOMEM || err == -ENOSPC)
+ return BLK_MQ_RQ_QUEUE_BUSY;
+ return BLK_MQ_RQ_QUEUE_ERROR;
}

if (last)
--
1.9.1