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.
CRs-Fixed: 2122802
Change-Id: Idb147edb9de364f76bd02df9069954f9c9e29b67
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>
Git-commit: d24406c85d123df773bc4df88ad5da2233896919
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ed443b5..0a12fa6 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1631,9 +1631,10 @@
{
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);
+ }
}
EXPORT_SYMBOL(udp_sk_rx_dst_set);
@@ -1958,13 +1959,11 @@
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 108288c..7e5d8ed 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -933,12 +933,11 @@
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);
}
}