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authorEric Dumazet <edumazet@google.com>2014-09-18 19:02:05 +0400
committerDavid S. Miller <davem@davemloft.net>2014-09-22 22:21:47 +0400
commit257117862634d89de33fec74858b1a0ba5ab444b (patch)
tree799321753c9f5ac9358c708bced556df7e309772
parent476c18850c6cbaa3f2bb661ae9710645081563b9 (diff)
downloadlinux-257117862634d89de33fec74858b1a0ba5ab444b.tar.xz
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 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 <edumazet@google.com> Fixes: e0f31d849867 ("flow_keys: Record IP layer protocol in skb_flow_dissect()") Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/sch_generic.h3
-rw-r--r--net/sched/sch_choke.c18
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);
}
/*