On 11/27/23 3:24 PM, Yoshihiro Shimoda wrote:
> Fix races between ravb_tx_timeout_work() and functions of net_device_ops
> and ethtool_ops by using rtnl_trylock() and rtnl_unlock(). Note that
> since ravb_close() is under the rtnl lock and calls cancel_work_sync(),
> ravb_tx_timeout_work() should calls rtnl_trylock(). Otherwise, a deadlock
> may happen in ravb_tx_timeout_work() like below:
>
> CPU0 CPU1
> ravb_tx_timeout()
> schedule_work()
> ...
> __dev_close_many()
> // Under rtnl lock
> ravb_close()
> cancel_work_sync()
> // Waiting
> ravb_tx_timeout_work()
> rtnl_lock()
> // This is possible to cause a deadlock
>
> If rtnl_trylock() fails, rescheduling the work with sleep for 1 msec.
>
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
[...]
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index c70cff80cc99..7c007ecd3ff6 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1874,6 +1874,12 @@ static void ravb_tx_timeout_work(struct work_struct *work)
> struct net_device *ndev = priv->ndev;
> int error;
>
> + if (!rtnl_trylock()) {
> + usleep_range(1000, 2000);
Why not msleep(1) though?
> + schedule_work(&priv->work);
> + return;
> + }
> +
> netif_tx_stop_all_queues(ndev);
>
> /* Stop PTP Clock driver */
[...]
MBR, Sergey
