5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 9fba1eb39e2f74d2002c5cbcf1d4435d37a4f752 ]
Add READ_ONCE() annotations because np->rxpmtu can be changed while udpv6_recvmsg() and rawv6_recvmsg() read it.
Since this is a very rarely used feature, and that udpv6_recvmsg() and rawv6_recvmsg() read np->rxopt anyway, change the test order so that np->rxpmtu does not need to be in a hot cache line.
Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Willem de Bruijn willemb@google.com Reviewed-by: David Ahern dsahern@kernel.org Reviewed-by: Kuniyuki Iwashima kuniyu@google.com Link: https://patch.msgid.link/20250916160951.541279-4-edumazet@google.com Reviewed-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/raw.c | 2 +- net/ipv6/udp.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c index 731485b18de31..90d828c98b736 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -474,7 +474,7 @@ static int rawv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, if (flags & MSG_ERRQUEUE) return ipv6_recv_error(sk, msg, len, addr_len);
- if (np->rxpmtu && np->rxopt.bits.rxpmtu) + if (np->rxopt.bits.rxpmtu && READ_ONCE(np->rxpmtu)) return ipv6_recv_rxpmtu(sk, msg, len, addr_len);
skb = skb_recv_datagram(sk, flags, noblock, &err); diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index db948e3a9bdc8..3ed835b308044 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -297,7 +297,7 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, if (flags & MSG_ERRQUEUE) return ipv6_recv_error(sk, msg, len, addr_len);
- if (np->rxpmtu && np->rxopt.bits.rxpmtu) + if (np->rxopt.bits.rxpmtu && READ_ONCE(np->rxpmtu)) return ipv6_recv_rxpmtu(sk, msg, len, addr_len);
try_again: