diff mbox

virtio-net: fix data corruption with OOM

Message ID 200910261211.52148.rusty@rustcorp.com.au (mailing list archive)
State New, archived
Headers show

Commit Message

Rusty Russell Oct. 26, 2009, 1:41 a.m. UTC
None
diff mbox

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -516,8 +516,7 @@  again:
 	/* Free up any pending old buffers before queueing new ones. */
 	free_old_xmit_skbs(vi);
 
-	/* Put new one in send queue and do transmit */
-	__skb_queue_head(&vi->send, skb);
+	/* Try to transmit */
 	capacity = xmit_skb(vi, skb);
 
 	/* This can happen with OOM and indirect buffers. */
@@ -531,8 +530,17 @@  again:
 		}
 		return NETDEV_TX_BUSY;
 	}
+	vi->svq->vq_ops->kick(vi->svq);
 
-	vi->svq->vq_ops->kick(vi->svq);
+	/*
+	 * Put new one in send queue.  You'd expect we'd need this before
+	 * xmit_skb calls add_buf(), since the callback can be triggered
+	 * immediately after that.  But since the callback just triggers
+	 * another call back here, normal network xmit locking prevents the
+	 * race.
+	 */
+	__skb_queue_head(&vi->send, skb);
+
 	/* Don't wait up for transmitted skbs to be freed. */
 	skb_orphan(skb);
 	nf_reset(skb);