[PATCH for-2.6.35] virtio_net: fix oom handling on tx

From: Michael S. Tsirkin
Date: Thu Jun 10 2010 - 11:25:59 EST


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@xxxxxxxxxx>
---
drivers/net/virtio_net.c | 15 ++++++++-------
1 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 85615a3..e48a06f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -563,7 +563,6 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
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);

@@ -572,12 +571,14 @@ 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(!virtqueue_enable_cb(vi->svq))) {
- virtqueue_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_warn(&dev->dev,
+ "Unexpected TX queue failure: %d\n",
+ capacity);
}
return NETDEV_TX_BUSY;
}
--
1.7.1.12.g42b7f
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