netdev - [PATCH net 3/4] can: j1939: abort multipacket broadcast session when timeout occurs

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Date:   Wed, 5 Aug 2020 11:50:24 +0800
From:   Zhang Changzhong <zhangchangzhong@...wei.com>
To:     <robin@...tonic.nl>, <linux@...pel-privat.de>,
        <kernel@...gutronix.de>, <socketcan@...tkopp.net>,
        <mkl@...gutronix.de>, <davem@...emloft.net>, <kuba@...nel.org>
CC:     <linux-can@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH net 3/4] can: j1939: abort multipacket broadcast session when timeout occurs

If timeout occurs, j1939_tp_rxtimer() first calls hrtimer_start() to
restart rxtimer, and then calls __j1939_session_cancel() to set
session->state = J1939_SESSION_WAITING_ABORT. At next timeout
expiration, because of the J1939_SESSION_WAITING_ABORT session state
j1939_tp_rxtimer() will call j1939_session_deactivate_activate_next()
to deactivate current session, and rxtimer won't be set.

But for multipacket broadcast session, __j1939_session_cancel() don't
set session->state = J1939_SESSION_WAITING_ABORT, thus current session
won't be deactivate and hrtimer_start() is called to start new
rxtimer again and again.

So fix it by moving session->state = J1939_SESSION_WAITING_ABORT out of
if (!j1939_cb_is_broadcast(&session->skcb)) statement.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>
---
 net/can/j1939/transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index dd6a120..5757f9f 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1055,9 +1055,9 @@ static void __j1939_session_cancel(struct j1939_session *session,
 	lockdep_assert_held(&session->priv->active_session_list_lock);

 	session->err = j1939_xtp_abort_to_errno(priv, err);
+	session->state = J1939_SESSION_WAITING_ABORT;
 	/* do not send aborts on incoming broadcasts */
 	if (!j1939_cb_is_broadcast(&session->skcb)) {
-		session->state = J1939_SESSION_WAITING_ABORT;
 		j1939_xtp_tx_abort(priv, &session->skcb,
 				   !session->transmission,
 				   err, session->skcb.addr.pgn);
-- 
2.9.5