Commit 25711786 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: sched: shrink struct qdisc_skb_cb to 28 bytes 



We cannot make struct qdisc_skb_cb bigger without impacting IPoIB,
or increasing skb->cb[] size.

Commit e0f31d84 ("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: default avatarEric Dumazet <edumazet@google.com>
Fixes: e0f31d84 ("flow_keys: Record IP layer protocol in skb_flow_dissect()")
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 476c1885

include/net/sch_generic.h

+2 −1
Original line number Diff line number Diff line
@@ -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)

net/sched/sch_choke.c

+14 −4
Original line number Diff line number Diff line
@@ -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);

}



/*

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