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Message-Id: <1454488017-8822-1-git-send-email-hans.westgaard.ry@oracle.com> Date: Wed, 3 Feb 2016 09:26:57 +0100 From: Hans Westgaard Ry <hans.westgaard.ry@...cle.com> To: unlisted-recipients:; (no To-header on input) Cc: Hans Westgaard Ry <hans.westgaard.ry@...cle.com>, "David S. Miller" <davem@...emloft.net>, Alexey Kuznetsov <kuznet@....inr.ac.ru>, James Morris <jmorris@...ei.org>, Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>, Patrick McHardy <kaber@...sh.net>, Tom Herbert <tom@...bertland.com>, Pablo Neira Ayuso <pablo@...filter.org>, Eric Dumazet <edumazet@...gle.com>, Florian Westphal <fw@...len.de>, Jiri Pirko <jiri@...nulli.us>, Alexander Duyck <alexander.h.duyck@...hat.com>, Michal Hocko <mhocko@...e.com>, Linus Lüssing <linus.luessing@...3.blue>, Hannes Frederic Sowa <hannes@...essinduktion.org>, Herbert Xu <herbert@...dor.apana.org.au>, Tejun Heo <tj@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Alexey Kodanev <alexey.kodanev@...cle.com>, Håkon Bugge <haakon.bugge@...cle.com>, linux-kernel@...r.kernel.org (open list), netdev@...r.kernel.org (open list:NETWORKING [GENERAL]) Subject: [PATCH v3] net:Add sysctl_max_skb_frags 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 <hans.westgaard.ry@...cle.com> Reviewed-by: Håkon Bugge <haakon.bugge@...cle.com> --- 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
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