From 9eb5bf838d06aa6ddebe4aca6b5cedcf2eb53b86 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 3 Jul 2013 05:02:22 -0700 Subject: [PATCH] net: sock: fix TCP_SKB_MIN_TRUESIZE commit eea86af6b1e18d ("net: sock: adapt SOCK_MIN_RCVBUF and SOCK_MIN_SNDBUF") forgot the sk_buff alignment taken into account in __alloc_skb() : skb->truesize = SKB_TRUESIZE(size); While above commit fixed the sender issue, the receiver is still dropping the second packet (on loopback device), because the receiver socket can not really hold two skbs : First packet truesize already is above sk_rcvbuf, so even TCP coalescing cannot help. On a typical 64bit build, each tcp skb truesize is 2304, instead of 2272 Signed-off-by: Eric Dumazet Cc: Daniel Borkmann Cc: Neal Cardwell Acked-by: Neal Cardwell Tested-by: Neal Cardwell Signed-off-by: David S. Miller --- include/net/sock.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/sock.h b/include/net/sock.h index ea6206c..95a5a2c 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2052,7 +2052,7 @@ static inline void sk_wake_async(struct sock *sk, int how, int band) * Note: for send buffers, TCP works better if we can build two skbs at * minimum. */ -#define TCP_SKB_MIN_TRUESIZE (2048 + sizeof(struct sk_buff)) +#define TCP_SKB_MIN_TRUESIZE (2048 + SKB_DATA_ALIGN(sizeof(struct sk_buff))) #define SOCK_MIN_SNDBUF (TCP_SKB_MIN_TRUESIZE * 2) #define SOCK_MIN_RCVBUF TCP_SKB_MIN_TRUESIZE -- 2.7.4