net: Recompute sk_txhash on negative routing advice

tomratbert · davem330 · commit 265f94ff54d6 · 2015-07-29T22:44:05.000-07:00
When a connection is failing a transport protocol calls
dst_negative_advice to try to get a better route. This patch includes
changing the sk_txhash in that function. This provides a rudimentary
method to try to find a different path in the network since sk_txhash
affects ECMP on the local host and through the network (via flow labels
or UDP source port in encapsulation).

Signed-off-by: Tom Herbert &lt;tom@herbertland.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/include/net/sock.h b/include/net/sock.h
@@ -1695,6 +1695,12 @@ static inline void sk_set_txhash(struct sock *sk)
 		sk->sk_txhash = 1;
 }
 
+static inline void sk_rethink_txhash(struct sock *sk)
+{
+	if (sk->sk_txhash)
+		sk_set_txhash(sk);
+}
+
 static inline struct dst_entry *
 __sk_dst_get(struct sock *sk)
 {
@@ -1719,6 +1725,8 @@ static inline void dst_negative_advice(struct sock *sk)
 {
 	struct dst_entry *ndst, *dst = __sk_dst_get(sk);
 
+	sk_rethink_txhash(sk);
+
 	if (dst && dst->ops->negative_advice) {
 		ndst = dst->ops->negative_advice(dst);
 

Original file line number	Diff line number	Diff line change
`@@ -1695,6 +1695,12 @@ static inline void sk_set_txhash(struct sock *sk)`
`1695`	`1695`	`sk->sk_txhash = 1;`
`1696`	`1696`	`}`
`1697`	`1697`
	`1698`	`+static inline void sk_rethink_txhash(struct sock *sk)`
	`1699`	`+{`
	`1700`	`+ if (sk->sk_txhash)`
	`1701`	`+ sk_set_txhash(sk);`
	`1702`	`+}`
	`1703`	`+`
`1698`	`1704`	`static inline struct dst_entry *`
`1699`	`1705`	`__sk_dst_get(struct sock *sk)`
`1700`	`1706`	`{`
`@@ -1719,6 +1725,8 @@ static inline void dst_negative_advice(struct sock *sk)`
`1719`	`1725`	`{`
`1720`	`1726`	`struct dst_entry ndst, dst = __sk_dst_get(sk);`
`1721`	`1727`
	`1728`	`+ sk_rethink_txhash(sk);`
	`1729`	`+`
`1722`	`1730`	`if (dst && dst->ops->negative_advice) {`
`1723`	`1731`	`ndst = dst->ops->negative_advice(dst);`
`1724`	`1732`