[PATCH] can: isotp: isotp_sendmsg(): fix return error fix on TX path

[Oliver Hartkopp <socketcan@hartkopp.net>]

With commit d674a8f123b4 ("can: isotp: isotp_sendmsg(): fix return error
on FC timeout on TX path") the missing correct return value in the case
of a protocol error was introduced.

But the way the error value has been read and sent to the user space does
not follow the common scheme to clear the error after reading which is
provided by the sock_error() function. This leads to an error report at
the following write() attempt although everything should be working.

Fixes: d674a8f123b4 ("can: isotp: isotp_sendmsg(): fix return error on FC timeout on TX path")
Reported-by: Carsten Schmidt <carsten.schmidt-achim@t-online.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/isotp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 84f9aba02901..ca9d728d6d72 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1110,12 +1110,13 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 		/* wait for complete transmission of current pdu */
 		err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
 		if (err)
 			goto err_event_drop;
 
-		if (sk->sk_err)
-			return -sk->sk_err;
+		err = sock_error(sk);
+		if (err)
+			return err;
 	}
 
 	return size;
 
 err_event_drop:
-- 
2.30.2