[PATCH 5.4 05/38] can: raw: add support for SO_TXTIME/SCM_TXTIME

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Kleine-Budde <mkl@pengutronix.de>

[ Upstream commit 51a0d5e51178fcd147c1b8fdab2ed16b561326db ]

This patch calls into sock_cmsg_send() to parse the user supplied
control information into a struct sockcm_cookie. Then assign the
requested transmit time to the skb.

This makes it possible to use the Earliest TXTIME First (ETF) packet
scheduler with the CAN_RAW protocol. The user can send a CAN_RAW frame
with a TXTIME and the kernel (with the ETF scheduler) will take care
of sending it to the network interface.

Link: https://lore.kernel.org/all/20220502091946.1916211-3-mkl@pengutronix.de
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Stable-dep-of: 7f6ca95d16b9 ("net: Implement missing getsockopt(SO_TIMESTAMPING_NEW)")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/can/raw.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/can/raw.c b/net/can/raw.c
index bb837019d1724..2700153262771 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -770,6 +770,7 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 {
 	struct sock *sk = sock->sk;
 	struct raw_sock *ro = raw_sk(sk);
+	struct sockcm_cookie sockc;
 	struct sk_buff *skb;
 	struct net_device *dev;
 	int ifindex;
@@ -815,11 +816,19 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	if (err < 0)
 		goto free_skb;
 
-	skb_setup_tx_timestamp(skb, sk->sk_tsflags);
+	sockcm_init(&sockc, sk);
+	if (msg->msg_controllen) {
+		err = sock_cmsg_send(sk, msg, &sockc);
+		if (unlikely(err))
+			goto free_skb;
+	}
 
 	skb->dev = dev;
 	skb->sk  = sk;
 	skb->priority = sk->sk_priority;
+	skb->tstamp = sockc.transmit_time;
+
+	skb_setup_tx_timestamp(skb, sockc.tsflags);
 
 	err = can_send(skb, ro->loopback);
 
-- 
2.43.0