Merge tag 'linux-can-fixes-for-6.19-20251218' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2025-12-18

this is a pull request of 3 patches for net/main.

Tetsuo Handa contributes 2 patches to fix race windows in the j1939
protocol to properly handle disappearing network devices.

The last patch is by me, it fixes a build dependency with the CAN
drivers, that got introduced while fixing a dependency between the CAN
protocol and CAN device code.

linux-can-fixes-for-6.19-20251218

* tag 'linux-can-fixes-for-6.19-20251218' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can:
  can: fix build dependency
  can: j1939: make j1939_sk_bind() fail if device is no longer registered
  can: j1939: make j1939_session_activate() fail if device is no longer registered
====================

Link: https://patch.msgid.link/20251218123132.664533-1-mkl@pengutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Paolo Abeni

drivers/net/can/Kconfig

@@ -17,7 +17,7 @@ menuconfig CAN_DEV
 	  virtual ones. If you own such devices or plan to use the virtual CAN
 	  interfaces to develop applications, say Y here.
 
-if CAN_DEV
+if CAN_DEV && CAN
 
 config CAN_VCAN
 	tristate "Virtual Local CAN Interface (vcan)"

net/can/j1939/socket.c

@@ -482,6 +482,12 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr_unsized *uaddr, in
 			goto out_release_sock;
 		}
 
+		if (ndev->reg_state != NETREG_REGISTERED) {
+			dev_put(ndev);
+			ret = -ENODEV;
+			goto out_release_sock;
+		}
+
 		can_ml = can_get_ml_priv(ndev);
 		if (!can_ml) {
 			dev_put(ndev);

net/can/j1939/transport.c

@@ -1567,6 +1567,8 @@ int j1939_session_activate(struct j1939_session *session)
 	if (active) {
 		j1939_session_put(active);
 		ret = -EAGAIN;
+	} else if (priv->ndev->reg_state != NETREG_REGISTERED) {
+		ret = -ENODEV;
 	} else {
 		WARN_ON_ONCE(session->state != J1939_SESSION_NEW);
 		list_add_tail(&session->active_session_list_entry,