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Subject[ 099/108] net: fix napi_reuse_skb() skb reserve
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <eric.dumazet@gmail.com>

[ Upstream commit 2a2a459eeeff48640dc557548ce576d666ab06ed ]

napi->skb is allocated in napi_get_frags() using
netdev_alloc_skb_ip_align(), with a reserve of NET_SKB_PAD +
NET_IP_ALIGN bytes.

However, when such skb is recycled in napi_reuse_skb(), it ends with a
reserve of NET_IP_ALIGN which is suboptimal.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/dev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3504,7 +3504,8 @@ EXPORT_SYMBOL(napi_gro_receive);
static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
{
__skb_pull(skb, skb_headlen(skb));
- skb_reserve(skb, NET_IP_ALIGN - skb_headroom(skb));
+ /* restore the reserve we had after netdev_alloc_skb_ip_align() */
+ skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
skb->vlan_tci = 0;
skb->dev = napi->dev;
skb->skb_iif = 0;



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