Commit d24406c8 authored by Wei Wang's avatar Wei Wang Committed by David S. Miller

udp: call dst_hold_safe() in udp_sk_rx_set_dst()

In udp_v4/6_early_demux() code, we try to hold dst->__refcnt for
dst with DST_NOCACHE flag. This is because later in udp_sk_rx_dst_set()
function, we will try to cache this dst in sk for connected case.
However, a better way to achieve this is to not try to hold dst in
early_demux(), but in udp_sk_rx_dst_set(), call dst_hold_safe(). This
approach is also more consistant with how tcp is handling it. And it
will make later changes simpler.
Signed-off-by: default avatarWei Wang <[email protected]>
Acked-by: default avatarMartin KaFai Lau <[email protected]>
Signed-off-by: default avatarDavid S. Miller <[email protected]>
parent 1758fd46
......@@ -1977,9 +1977,10 @@ static void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
{
struct dst_entry *old;
dst_hold(dst);
old = xchg(&sk->sk_rx_dst, dst);
dst_release(old);
if (dst_hold_safe(dst)) {
old = xchg(&sk->sk_rx_dst, dst);
dst_release(old);
}
}
/*
......@@ -2303,13 +2304,11 @@ void udp_v4_early_demux(struct sk_buff *skb)
if (dst)
dst = dst_check(dst, 0);
if (dst) {
/* DST_NOCACHE can not be used without taking a reference */
if (dst->flags & DST_NOCACHE) {
if (likely(atomic_inc_not_zero(&dst->__refcnt)))
skb_dst_set(skb, dst);
} else {
skb_dst_set_noref(skb, dst);
}
/* set noref for now.
* any place which wants to hold dst has to call
* dst_hold_safe()
*/
skb_dst_set_noref(skb, dst);
}
}
......
......@@ -920,12 +920,11 @@ static void udp_v6_early_demux(struct sk_buff *skb)
if (dst)
dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie);
if (dst) {
if (dst->flags & DST_NOCACHE) {
if (likely(atomic_inc_not_zero(&dst->__refcnt)))
skb_dst_set(skb, dst);
} else {
skb_dst_set_noref(skb, dst);
}
/* set noref for now.
* any place which wants to hold dst has to call
* dst_hold_safe()
*/
skb_dst_set_noref(skb, dst);
}
}
......
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