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authorWei Wang <weiwan@google.com>2017-06-17 10:42:25 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-17 22:53:59 -0400
commitd24406c85d123df773bc4df88ad5da2233896919 (patch)
tree745345616e8577a837668e5191f51abf36ace0aa /net/ipv4/udp.c
parent1758fd4688eb92c796e75bdb1d256dc558ef9581 (diff)
downloadlinux-d24406c85d123df773bc4df88ad5da2233896919.tar.bz2
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: Wei Wang <weiwan@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp.c')
-rw-r--r--net/ipv4/udp.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 2bc638c48b86..f3450f092d71 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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);
}
}