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Subject[087/143] virtio_net: fix oom handling on tx
2.6.32-longterm review patch.  If anyone has any objections, please let us know.

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

commit 58eba97d0774c69b1cf3e5a8ac74419409d1abbf upstream.

virtio net will never try to overflow the TX ring, so the only reason
add_buf may fail is out of memory. Thus, we can not stop the
device until some request completes - there's no guarantee anything
at all is outstanding.

Make the error message clearer as well: error here does not
indicate queue full.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/net/virtio_net.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -525,7 +525,6 @@ static netdev_tx_t start_xmit(struct sk_
struct virtnet_info *vi = netdev_priv(dev);
int capacity;

-again:
/* Free up any pending old buffers before queueing new ones. */
free_old_xmit_skbs(vi);

@@ -534,14 +533,20 @@ again:

/* This can happen with OOM and indirect buffers. */
if (unlikely(capacity < 0)) {
- netif_stop_queue(dev);
- dev_warn(&dev->dev, "Unexpected full queue\n");
- if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
- vi->svq->vq_ops->disable_cb(vi->svq);
- netif_start_queue(dev);
- goto again;
+ if (net_ratelimit()) {
+ if (likely(capacity == -ENOMEM)) {
+ dev_warn(&dev->dev,
+ "TX queue failure: out of memory\n");
+ } else {
+ dev->stats.tx_fifo_errors++;
+ dev_warn(&dev->dev,
+ "Unexpected TX queue failure: %d\n",
+ capacity);
+ }
}
- return NETDEV_TX_BUSY;
+ dev->stats.tx_dropped++;
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
}
vi->svq->vq_ops->kick(vi->svq);




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