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authorLennert Buytenhek <buytenh@wantstofly.org>2009-05-25 00:42:34 -0700
committerDavid S. Miller <davem@davemloft.net>2009-05-25 00:42:34 -0700
commit4e2fd555199977c5994d1a4d2d3b8761b20ca4c7 (patch)
tree474454cd8fbe7f643d5ae5136bf43ec8a8513359
parent0975ecba3b670df7c488a5e0e6fe9f1f370a8ad8 (diff)
gianfar: fix BUG under load after introduction of skb recycling
Since commit 0fd56bb5be6455d0d42241e65aed057244665e5e ("gianfar: Add support for skb recycling"), gianfar puts skbuffs that are in the rx ring back onto the recycle list as-is in case there was a receive error, but this breaks the following invariant: that all skbuffs on the recycle list have skb->data = skb->head + NET_SKB_PAD. The RXBUF_ALIGNMENT realignment done in gfar_new_skb() will be done twice on skbuffs recycled in this way, causing there not to be enough room in the skb anymore to receive a full packet, eventually leading to an skb_over_panic from gfar_clean_rx_ring() -> skb_put(). Resetting the skb->data pointer to skb->head + NET_SKB_PAD before putting the skb back onto the recycle list restores the mentioned invariant, and should fix this issue. Reported-by: Michael Guntsche <mike@it-loops.com> Tested-by: Michael Guntsche <mike@it-loops.com> Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/gianfar.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index b2c49679bba7..a0519184e54e 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -1885,8 +1885,17 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit)
if (unlikely(!newskb))
newskb = skb;
- else if (skb)
+ else if (skb) {
+ /*
+ * We need to reset ->data to what it
+ * was before gfar_new_skb() re-aligned
+ * it to an RXBUF_ALIGNMENT boundary
+ * before we put the skb back on the
+ * recycle list.
+ */
+ skb->data = skb->head + NET_SKB_PAD;
__skb_queue_head(&priv->rx_recycle, skb);
+ }
} else {
/* Increment the number of packets */
dev->stats.rx_packets++;