[SCSI] virtio-scsi: unlock during kick

Separate virtqueue_kick_prepare from virtqueue_notify, so that the
expensive vmexit is done without holding the lock.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 1b384311726897bff5ba3e1014a53a536eccc210..b0ad5aa6b552c442e4f57b23b8848570b8315472 100644 (file)
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -264,9 +264,11 @@ static int virtscsi_kick_cmd(struct virtio_scsi *vscsi, struct virtqueue *vq,
 
        ret = virtqueue_add_buf(vq, vscsi->sg, out_num, in_num, cmd, gfp);
        if (ret >= 0)
-               virtqueue_kick(vq);
+               ret = virtqueue_kick_prepare(vq);
 
        spin_unlock_irqrestore(&vscsi->vq_lock, flags);
+       if (ret > 0)
+               virtqueue_notify(vq);
        return ret;
 }