From: Wei Wang <tracywwnj@gmail.com>
To: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Cc: Eric Dumazet <edumazet@google.com>,
Martin KaFai Lau <kafai@fb.com>, Wei Wang <weiwan@google.com>
Subject: [PATCH v2 net-next 02/21] udp: call dst_hold_safe() in udp_sk_rx_set_dst()
Date: Sat, 17 Jun 2017 10:42:25 -0700 [thread overview]
Message-ID: <20170617174244.132862-3-tracywwnj@gmail.com> (raw)
In-Reply-To: <20170617174244.132862-1-tracywwnj@gmail.com>
From: Wei Wang <weiwan@google.com>
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>
---
net/ipv4/udp.c | 19 +++++++++----------
net/ipv6/udp.c | 11 +++++------
2 files changed, 14 insertions(+), 16 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);
}
}
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 2e9b52bded2d..2b33847bf931 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -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);
}
}
--
2.13.1.518.g3df882009-goog
next prev parent reply other threads:[~2017-06-17 17:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-17 17:42 [PATCH v2 net-next 00/21] remove dst garbage collector logic Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 01/21] ipv6: remove unnecessary dst_hold() in ip6_fragment() Wei Wang
2017-06-17 17:42 ` Wei Wang [this message]
2017-06-17 17:42 ` [PATCH v2 net-next 03/21] net: use loopback dev when generating blackhole route Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 04/21] net: introduce DST_NOGC in dst_release() to destroy dst based on refcnt Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 05/21] net: introduce a new function dst_dev_put() Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 06/21] ipv4: take dst->__refcnt when caching dst in fib Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 07/21] ipv4: call dst_dev_put() properly Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 08/21] ipv4: call dst_hold_safe() properly Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 09/21] ipv4: mark DST_NOGC and remove the operation of dst_free() Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 10/21] ipv6: take dst->__refcnt for insertion into fib6 tree Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 11/21] ipv6: call dst_dev_put() properly Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 12/21] ipv6: call dst_hold_safe() properly Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 13/21] ipv6: mark DST_NOGC and remove the operation of dst_free() Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 14/21] ipv6: get rid of icmp6 dst garbage collector Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 15/21] xfrm: take refcnt of dst when creating struct xfrm_dst bundle Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 16/21] decnet: take dst->__refcnt when struct dn_route is created Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 17/21] net: remove dst gc related code Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 18/21] net: remove DST_NOGC flag Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 19/21] net: remove DST_NOCACHE flag Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 20/21] net: reorder all the dst flags Wei Wang
2017-06-17 17:42 ` [PATCH v2 net-next 21/21] net: add debug atomic_inc_not_zero() in dst_hold() Wei Wang
2017-06-18 2:55 ` [PATCH v2 net-next 00/21] remove dst garbage collector logic David Miller
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