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| author | Lennert Buytenhek <buytenh@wantstofly.org> | 2009-05-25 00:42:34 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-05-25 00:42:34 -0700 |
| commit | 4e2fd555199977c5994d1a4d2d3b8761b20ca4c7 (patch) | |
| tree | 474454cd8fbe7f643d5ae5136bf43ec8a8513359 /drivers/net | |
| parent | 0975ecba3b670df7c488a5e0e6fe9f1f370a8ad8 (diff) | |
| download | lwn-4e2fd555199977c5994d1a4d2d3b8761b20ca4c7.tar.gz lwn-4e2fd555199977c5994d1a4d2d3b8761b20ca4c7.zip | |
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>
Diffstat (limited to 'drivers/net')
| -rw-r--r-- | drivers/net/gianfar.c | 11 |
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++; |