Commit 87aaadbf authored Nov 27, 2023 by Yoshihiro Shimoda Committed by Greg Kroah-Hartman Dec 08, 2023

ravb: Fix races between ravb_tx_timeout_work() and net related ops



[ Upstream commit 9870257a0a338cd8d6c1cddab74e703f490f6779 ]

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: c156633f ("Renesas Ethernet AVB driver proper")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/20231127122420.3706751-1-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent be70b329

drivers/net/ethernet/renesas/ravb_main.c

+10 −1

Original line number	Original line	Diff line number	Diff line
	@@ -1484,6 +1484,12 @@ static void ravb_tx_timeout_work(struct work_struct *work)
	struct net_device *ndev = priv->ndev;		struct net_device *ndev = priv->ndev;
	int error;		int error;

			if (!rtnl_trylock()) {
			usleep_range(1000, 2000);
			schedule_work(&priv->work);
			return;
			}

	netif_tx_stop_all_queues(ndev);		netif_tx_stop_all_queues(ndev);

	/* Stop PTP Clock driver */		/* Stop PTP Clock driver */
	@@ -1516,7 +1522,7 @@ static void ravb_tx_timeout_work(struct work_struct *work)
	*/		*/
	netdev_err(ndev, "%s: ravb_dmac_init() failed, error %d\n",		netdev_err(ndev, "%s: ravb_dmac_init() failed, error %d\n",
	__func__, error);		__func__, error);
	return;		goto out_unlock;
	}		}
	ravb_emac_init(ndev);		ravb_emac_init(ndev);

	@@ -1526,6 +1532,9 @@ static void ravb_tx_timeout_work(struct work_struct *work)
	ravb_ptp_init(ndev, priv->pdev);		ravb_ptp_init(ndev, priv->pdev);

	netif_tx_start_all_queues(ndev);		netif_tx_start_all_queues(ndev);

			out_unlock:
			rtnl_unlock();
	}		}

	/* Packet transmit function for Ethernet AVB */		/* Packet transmit function for Ethernet AVB */