From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756726AbcBCI3V (ORCPT ); Wed, 3 Feb 2016 03:29:21 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:41662 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756546AbcBCI3S (ORCPT ); Wed, 3 Feb 2016 03:29:18 -0500 From: Hans Westgaard Ry Cc: Hans Westgaard Ry , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , Tom Herbert , Pablo Neira Ayuso , Eric Dumazet , Florian Westphal , Jiri Pirko , Alexander Duyck , Michal Hocko , =?UTF-8?q?Linus=20L=C3=BCssing?= , Hannes Frederic Sowa , Herbert Xu , Tejun Heo , Andrew Morton , Alexey Kodanev , =?UTF-8?q?H=C3=A5kon=20Bugge?= , linux-kernel@vger.kernel.org (open list), netdev@vger.kernel.org (open list:NETWORKING [GENERAL]) Subject: [PATCH v3] net:Add sysctl_max_skb_frags Date: Wed, 3 Feb 2016 09:26:57 +0100 Message-Id: <1454488017-8822-1-git-send-email-hans.westgaard.ry@oracle.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <568F87AC.60405@oracle.com> References: <568F87AC.60405@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Source-IP: userv0021.oracle.com [156.151.31.71] To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Devices may have limits on the number of fragments in an skb they support. Current codebase uses a constant as maximum for number of fragments one skb can hold and use. When enabling scatter/gather and running traffic with many small messages the codebase uses the maximum number of fragments and may thereby violate the max for certain devices. The patch introduces a global variable as max number of fragments. Signed-off-by: Hans Westgaard Ry Reviewed-by: Håkon Bugge --- include/linux/skbuff.h | 1 + net/core/skbuff.c | 2 ++ net/core/sysctl_net_core.c | 10 ++++++++++ net/ipv4/tcp.c | 4 ++-- 4 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 4355129..fe47ad3 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -219,6 +219,7 @@ struct sk_buff; #else #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1) #endif +extern int sysctl_max_skb_frags; typedef struct skb_frag_struct skb_frag_t; diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 152b9c7..c336b97 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -79,6 +79,8 @@ struct kmem_cache *skbuff_head_cache __read_mostly; static struct kmem_cache *skbuff_fclone_cache __read_mostly; +int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS; +EXPORT_SYMBOL(sysctl_max_skb_frags); /** * skb_panic - private function for out-of-line support diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 95b6139..a6beb7b 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -26,6 +26,7 @@ static int zero = 0; static int one = 1; static int min_sndbuf = SOCK_MIN_SNDBUF; static int min_rcvbuf = SOCK_MIN_RCVBUF; +static int max_skb_frags = MAX_SKB_FRAGS; static int net_msg_warn; /* Unused, but still a sysctl */ @@ -392,6 +393,15 @@ static struct ctl_table net_core_table[] = { .mode = 0644, .proc_handler = proc_dointvec }, + { + .procname = "max_skb_frags", + .data = &sysctl_max_skb_frags, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &one, + .extra2 = &max_skb_frags, + }, { } }; diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index c82cca1..3dc7a2fd 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -938,7 +938,7 @@ new_segment: i = skb_shinfo(skb)->nr_frags; can_coalesce = skb_can_coalesce(skb, i, page, offset); - if (!can_coalesce && i >= MAX_SKB_FRAGS) { + if (!can_coalesce && i >= sysctl_max_skb_frags) { tcp_mark_push(tp, skb); goto new_segment; } @@ -1211,7 +1211,7 @@ new_segment: if (!skb_can_coalesce(skb, i, pfrag->page, pfrag->offset)) { - if (i == MAX_SKB_FRAGS || !sg) { + if (i == sysctl_max_skb_frags || !sg) { tcp_mark_push(tp, skb); goto new_segment; } -- 2.4.3