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can: j1939: use netdevice_tracker for j1939_{priv,session,ecu} tracking

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  unregister_netdevice: waiting for vcan0 to become free. Usage count = 2

problem. A debug printk() patch in linux-next-20260508 identified that
there is dev_hold()/dev_put() imbalance in j1939_priv management.

  Call trace for vcan0[26] +4 at
     __dev_hold include/linux/netdevice.h:4470 [inline]
     netdev_hold include/linux/netdevice.h:4513 [inline]
     dev_hold include/linux/netdevice.h:4536 [inline]
     j1939_priv_create net/can/j1939/main.c:140 [inline]
     j1939_netdev_start+0x36b/0xc10 net/can/j1939/main.c:268
     j1939_sk_bind+0x853/0xb30 net/can/j1939/socket.c:506
     __sys_bind_socket net/socket.c:1948 [inline]
     __sys_bind+0x2e9/0x410 net/socket.c:1979

  Call trace for vcan0[28] -3 at
     __dev_put include/linux/netdevice.h:4456 [inline]
     netdev_put include/linux/netdevice.h:4523 [inline]
     dev_put include/linux/netdevice.h:4548 [inline]
     __j1939_priv_release net/can/j1939/main.c:166 [inline]
     kref_put include/linux/kref.h:65 [inline]
     j1939_priv_put+0x128/0x270 net/can/j1939/main.c:172
     j1939_sk_sock_destruct+0x52/0x90 net/can/j1939/socket.c:388
     __sk_destruct+0x8d/0x9d0 net/core/sock.c:2352
     rcu_do_batch kernel/rcu/tree.c:2617 [inline]
     rcu_core kernel/rcu/tree.c:2869 [inline]
     rcu_cpu_kthread+0x99e/0x1470 kernel/rcu/tree.c:2957
     smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
     kthread+0x388/0x470 kernel/kthread.c:436
     ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
     ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

This refcount leak in j1939_priv might be caused by a refcount leak in
j1939_{session,ecu} because j1939_{session,ecu} holds a ref on j1939_priv.
For further investigation using upstream kernels, enable netdevice_tracker
in j1939_{priv,session,ecu} management.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20260728055835.1151785-2-o.rempel@pengutronix.de
Cc: stable@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Tetsuo Handa 2026-07-28 07:58:34 +02:00 committed by Marc Kleine-Budde
parent 3bd438a58e
commit d2fb981384
4 changed files with 11 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/can/j1939/bus.c
View File

@ -20,6 +20,7 @@ static void __j1939_ecu_release(struct kref *kref)
struct j1939_priv *priv = ecu->priv;
list_del(&ecu->list);
netdev_put(priv->ndev, &ecu->priv_dev_tracker);
kfree(ecu);
j1939_priv_put(priv);
}
@ -155,6 +156,7 @@ struct j1939_ecu *j1939_ecu_create_locked(struct j1939_priv *priv, name_t name)
if (!ecu)
return ERR_PTR(-ENOMEM);
kref_init(&ecu->kref);
netdev_hold(priv->ndev, &ecu->priv_dev_tracker, gfp_any());
ecu->addr = J1939_IDLE_ADDR;
ecu->name = name;

3
net/can/j1939/j1939-priv.h
View File

@ -38,6 +38,7 @@ struct j1939_ecu {
struct hrtimer ac_timer;
struct kref kref;
struct j1939_priv *priv;
netdevice_tracker priv_dev_tracker;
/* count users, to help transport protocol decide for interaction */
int nusers;
@ -60,6 +61,7 @@ struct j1939_priv {
rwlock_t lock;
struct net_device *ndev;
netdevice_tracker dev_tracker;
/* list of 256 ecu ptrs, that cache the claimed addresses.
* also protected by the above lock
@ -230,6 +232,7 @@ enum j1939_session_state {
struct j1939_session {
struct j1939_priv *priv;
netdevice_tracker priv_dev_tracker;
struct list_head active_session_list_entry;
struct list_head sk_session_queue_entry;
struct kref kref;

8
net/can/j1939/main.c
View File

@ -137,7 +137,7 @@ static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
priv->ndev = ndev;
kref_init(&priv->kref);
kref_init(&priv->rx_kref);
dev_hold(ndev);
netdev_hold(ndev, &priv->dev_tracker, GFP_KERNEL);
netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
@ -163,7 +163,7 @@ static void __j1939_priv_release(struct kref *kref)
WARN_ON_ONCE(!list_empty(&priv->ecus));
WARN_ON_ONCE(!list_empty(&priv->j1939_socks));
dev_put(ndev);
netdev_put(ndev, &priv->dev_tracker);
kfree(priv);
}
@ -281,7 +281,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
*/
kref_get(&priv_new->rx_kref);
mutex_unlock(&j1939_netdev_lock);
dev_put(ndev);
netdev_put(ndev, &priv->dev_tracker);
kfree(priv);
return priv_new;
}
@ -298,7 +298,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
j1939_priv_set(ndev, NULL);
mutex_unlock(&j1939_netdev_lock);
dev_put(ndev);
netdev_put(ndev, &priv->dev_tracker);
kfree(priv);
return ERR_PTR(ret);

2
net/can/j1939/transport.c
View File

@ -283,6 +283,7 @@ static void j1939_session_destroy(struct j1939_session *session)
kfree_skb(skb);
}
__j1939_session_drop(session);
netdev_put(session->priv->ndev, &session->priv_dev_tracker);
j1939_priv_put(session->priv);
kfree(session);
}
@ -1526,6 +1527,7 @@ static struct j1939_session *j1939_session_new(struct j1939_priv *priv,
INIT_LIST_HEAD(&session->active_session_list_entry);
INIT_LIST_HEAD(&session->sk_session_queue_entry);
kref_init(&session->kref);
netdev_hold(priv->ndev, &session->priv_dev_tracker, gfp_any());
j1939_priv_get(priv);
session->priv = priv;