Hello,
> From: Yoshihiro Shimoda, Sent: Thursday, October 19, 2023 8:33 PM
>
> 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
>
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Gentle ping. I confirmed that I could apply this patch on
the latest net.git / main branch.
Best regards,
Yoshihiro Shimoda
> ---
> Changes from v1:
<snip URL>
> - Modify commit description.
> - Use goto in a error path.
>
> drivers/net/ethernet/renesas/ravb_main.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 0ef0b88b7145..300c1885e1e1 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1874,6 +1874,9 @@ static void ravb_tx_timeout_work(struct work_struct *work)
> struct net_device *ndev = priv->ndev;
> int error;
>
> + if (!rtnl_trylock())
> + return;
> +
> netif_tx_stop_all_queues(ndev);
>
> /* Stop PTP Clock driver */
> @@ -1907,7 +1910,7 @@ static void ravb_tx_timeout_work(struct work_struct *work)
> */
> netdev_err(ndev, "%s: ravb_dmac_init() failed, error %d\n",
> __func__, error);
> - return;
> + goto out_unlock;
> }
> ravb_emac_init(ndev);
>
> @@ -1917,6 +1920,9 @@ static void ravb_tx_timeout_work(struct work_struct *work)
> ravb_ptp_init(ndev, priv->pdev);
>
> netif_tx_start_all_queues(ndev);
> +
> +out_unlock:
> + rtnl_unlock();
> }
>
> /* Packet transmit function for Ethernet AVB */
> --
> 2.25.1
