From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch fixes a regression bug in virtscsi_kick_cmd() that relinquishes
the acquired spinlocks in the incorrect order using the wrong spin_unlock
macros, namely releasing vq->vq_lock before tgt->tgt_lock while invoking
the calls to virtio_ring.c:virtqueue_add_buf() and friends.
This bug was originally introduced in v3.5-rc7 code with:
commit 2bd37f0fde99cbf8b78fb55f1128e8c3a63cf1da
Author: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Wed Jun 13 16:56:34 2012 +0200
[SCSI] virtio-scsi: split scatterlist per target
Go ahead and make sure that vq->vq_lock is relinquished w/ spin_unlock
first, then release tgt->tgt_lock w/ spin_unlock_irqrestore.
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/scsi/virtio_scsi.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 595af1a..b2abb8a 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -417,11 +417,11 @@ static int virtscsi_kick_cmd(struct virtio_scsi_target_state *tgt,
spin_lock(&vq->vq_lock);
ret = virtqueue_add_buf(vq->vq, tgt->sg, out_num, in_num, cmd, gfp);
- spin_unlock(&tgt->tgt_lock);
+ spin_unlock(&vq->vq_lock);
if (ret >= 0)
ret = virtqueue_kick_prepare(vq->vq);
- spin_unlock_irqrestore(&vq->vq_lock, flags);
+ spin_unlock_irqrestore(&tgt->tgt_lock, flags);
if (ret > 0)
virtqueue_notify(vq->vq);
--
1.7.2.5
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