From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net] net: sched: shrink struct qdisc_skb_cb to 28 bytes Date: Thu, 18 Sep 2014 08:02:05 -0700 Message-ID: <1411052525.7106.269.camel@edumazet-glaptop2.roam.corp.google.com> References: <1402338773-5996-1-git-send-email-_govind@gmx.com> <1402338773-5996-2-git-send-email-_govind@gmx.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Govindarajulu Varadarajan <_govind@gmx.com>, Yinghai Lu , David Miller , NetDev , ssujith@cisco.com, gvaradar@cisco.com, "Christian Benvenuti (benve)" To: Or Gerlitz Return-path: Received: from mail-pd0-f178.google.com ([209.85.192.178]:58950 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755841AbaIRPCI (ORCPT ); Thu, 18 Sep 2014 11:02:08 -0400 Received: by mail-pd0-f178.google.com with SMTP id p10so1571749pdj.9 for ; Thu, 18 Sep 2014 08:02:07 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet We cannot make struct qdisc_skb_cb bigger without impacting IPoIB, or increasing skb->cb[] size. Commit e0f31d849867 ("flow_keys: Record IP layer protocol in skb_flow_dissect()") broke IPoIB. Only current offender is sch_choke, and this one do not need an absolutely precise flow key. If we store 17 bytes of flow key, its more than enough. (Its the actual size of flow_keys if it was a packed structure, but we might add new fields at the end of it later) Signed-off-by: Eric Dumazet Fixes: e0f31d849867 ("flow_keys: Record IP layer protocol in skb_flow_dissect()") --- include/net/sch_generic.h | 3 ++- net/sched/sch_choke.c | 18 ++++++++++++++---- 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index a3cfb8ebeb53..620e086c0cbe 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -231,7 +231,8 @@ struct qdisc_skb_cb { unsigned int pkt_len; u16 slave_dev_queue_mapping; u16 _pad; - unsigned char data[24]; +#define QDISC_CB_PRIV_LEN 20 + unsigned char data[QDISC_CB_PRIV_LEN]; }; static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz) diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c index ed30e436128b..fb666d1e4de3 100644 --- a/net/sched/sch_choke.c +++ b/net/sched/sch_choke.c @@ -133,10 +133,16 @@ static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx) --sch->q.qlen; } +/* private part of skb->cb[] that a qdisc is allowed to use + * is limited to QDISC_CB_PRIV_LEN bytes. + * As a flow key might be too large, we store a part of it only. + */ +#define CHOKE_K_LEN min_t(u32, sizeof(struct flow_keys), QDISC_CB_PRIV_LEN - 3) + struct choke_skb_cb { u16 classid; u8 keys_valid; - struct flow_keys keys; + u8 keys[QDISC_CB_PRIV_LEN - 3]; }; static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb) @@ -163,22 +169,26 @@ static u16 choke_get_classid(const struct sk_buff *skb) static bool choke_match_flow(struct sk_buff *skb1, struct sk_buff *skb2) { + struct flow_keys temp; + if (skb1->protocol != skb2->protocol) return false; if (!choke_skb_cb(skb1)->keys_valid) { choke_skb_cb(skb1)->keys_valid = 1; - skb_flow_dissect(skb1, &choke_skb_cb(skb1)->keys); + skb_flow_dissect(skb1, &temp); + memcpy(&choke_skb_cb(skb1)->keys, &temp, CHOKE_K_LEN); } if (!choke_skb_cb(skb2)->keys_valid) { choke_skb_cb(skb2)->keys_valid = 1; - skb_flow_dissect(skb2, &choke_skb_cb(skb2)->keys); + skb_flow_dissect(skb2, &temp); + memcpy(&choke_skb_cb(skb2)->keys, &temp, CHOKE_K_LEN); } return !memcmp(&choke_skb_cb(skb1)->keys, &choke_skb_cb(skb2)->keys, - sizeof(struct flow_keys)); + CHOKE_K_LEN); } /*