From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neal Cardwell Subject: [PATCH v3 net-next 05/16] tcp: switch back to proper tcp_skb_cb size check in tcp_init() Date: Sun, 18 Sep 2016 18:03:42 -0400 Message-ID: <1474236233-28511-6-git-send-email-ncardwell@google.com> References: <1474236233-28511-1-git-send-email-ncardwell@google.com> Cc: netdev@vger.kernel.org, Eric Dumazet , Soheil Hassas Yeganeh , Neal Cardwell , Yuchung Cheng To: David Miller Return-path: Received: from mail-qt0-f182.google.com ([209.85.216.182]:35955 "EHLO mail-qt0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932704AbcIRWEM (ORCPT ); Sun, 18 Sep 2016 18:04:12 -0400 Received: by mail-qt0-f182.google.com with SMTP id l91so64341961qte.3 for ; Sun, 18 Sep 2016 15:04:12 -0700 (PDT) In-Reply-To: <1474236233-28511-1-git-send-email-ncardwell@google.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet Revert to the tcp_skb_cb size check that tcp_init() had before commit b4772ef879a8 ("net: use common macro for assering skb->cb[] available size in protocol families"). As related commit 744d5a3e9fe2 ("net: move skb->dropcount to skb->cb[]") explains, the sock_skb_cb_check_size() mechanism was added to ensure that there is space for dropcount, "for protocol families using it". But TCP is not a protocol using dropcount, so tcp_init() doesn't need to provision space for dropcount in the skb->cb[], and thus we can revert to the older form of the tcp_skb_cb size check. Doing so allows TCP to use 4 more bytes of the skb->cb[] space. Fixes: b4772ef879a8 ("net: use common macro for assering skb->cb[] available size in protocol families") Signed-off-by: Eric Dumazet Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng --- net/ipv4/tcp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 5b0b49c..53798e1 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3244,11 +3244,12 @@ static void __init tcp_init_mem(void) void __init tcp_init(void) { - unsigned long limit; int max_rshare, max_wshare, cnt; + unsigned long limit; + struct sk_buff *skb; unsigned int i; - sock_skb_cb_check_size(sizeof(struct tcp_skb_cb)); + BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb)); percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL); percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL); -- 2.8.0.rc3.226.g39d4020