diff options
| author | Wei Wang <weiwan@google.com> | 2017-06-17 10:42:25 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-17 22:53:59 -0400 |
| commit | d24406c85d123df773bc4df88ad5da2233896919 (patch) | |
| tree | 745345616e8577a837668e5191f51abf36ace0aa /net/ipv4/udp.c | |
| parent | 1758fd4688eb92c796e75bdb1d256dc558ef9581 (diff) | |
| download | lwn-d24406c85d123df773bc4df88ad5da2233896919.tar.gz lwn-d24406c85d123df773bc4df88ad5da2233896919.zip | |
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.c | 19 |
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); } } |