[PATCH net-next v2 2/7] net: initialize mark in sockcm_init

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

From: Willem de Bruijn <willemb@google.com>

Avoid open coding initialization of sockcm fields.
Avoid reading the sk_priority field twice.

This ensures all callers, existing and future, will correctly try a
cmsg passed mark before sk_mark.

This patch extends support for cmsg mark to:
packet_spkt and packet_tpacket and net/can/raw.c.

This patch extends support for cmsg priority to:
packet_spkt and packet_tpacket.

Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 include/net/sock.h     | 1 +
 net/can/raw.c          | 2 +-
 net/packet/af_packet.c | 9 ++++-----
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 8036b3b79cd8..767a60e80086 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1828,6 +1828,7 @@ static inline void sockcm_init(struct sockcm_cookie *sockc,
 			       const struct sock *sk)
 {
 	*sockc = (struct sockcm_cookie) {
+		.mark = READ_ONCE(sk->sk_mark),
 		.tsflags = READ_ONCE(sk->sk_tsflags),
 		.priority = READ_ONCE(sk->sk_priority),
 	};
diff --git a/net/can/raw.c b/net/can/raw.c
index 46e8ed9d64da..9b1d5f036f57 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -963,7 +963,7 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 
 	skb->dev = dev;
 	skb->priority = sockc.priority;
-	skb->mark = READ_ONCE(sk->sk_mark);
+	skb->mark = sockc.mark;
 	skb->tstamp = sockc.transmit_time;
 
 	skb_setup_tx_timestamp(skb, &sockc);
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c131e5ceea37..3e9ddf72cd03 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2102,8 +2102,8 @@ static int packet_sendmsg_spkt(struct socket *sock, struct msghdr *msg,
 
 	skb->protocol = proto;
 	skb->dev = dev;
-	skb->priority = READ_ONCE(sk->sk_priority);
-	skb->mark = READ_ONCE(sk->sk_mark);
+	skb->priority = sockc.priority;
+	skb->mark = sockc.mark;
 	skb_set_delivery_type_by_clockid(skb, sockc.transmit_time, sk->sk_clockid);
 	skb_setup_tx_timestamp(skb, &sockc);
 
@@ -2634,8 +2634,8 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
 
 	skb->protocol = proto;
 	skb->dev = dev;
-	skb->priority = READ_ONCE(po->sk.sk_priority);
-	skb->mark = READ_ONCE(po->sk.sk_mark);
+	skb->priority = sockc->priority;
+	skb->mark = sockc->mark;
 	skb_set_delivery_type_by_clockid(skb, sockc->transmit_time, po->sk.sk_clockid);
 	skb_setup_tx_timestamp(skb, sockc);
 	skb_zcopy_set_nouarg(skb, ph.raw);
@@ -3039,7 +3039,6 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
 		goto out_unlock;
 
 	sockcm_init(&sockc, sk);
-	sockc.mark = READ_ONCE(sk->sk_mark);
 	if (msg->msg_controllen) {
 		err = sock_cmsg_send(sk, msg, &sockc);
 		if (unlikely(err))
-- 
2.48.1.502.g6dc24dfdaf-goog