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>
---
Changes from v3:
https://lore.kernel.org/all/20231115022644.2316961-1-yoshihiro.shimoda.uh@xxxxxxxxxxx/
- Based on v2 patch. This means that delayed work is not used.
- Add rescheduling the work if rtnl_trylock() fails.
- Drop Reviewed-by tags because implementation was changed.
Changes from v2:
https://lore.kernel.org/netdev/20231019113308.1133944-1-yoshihiro.shimoda.uh@xxxxxxxxxxx/
- Add rescheduling if rtnl_trylock() fails and the netif is still running
and update commit description for it.
- Add Reviewed-by tags.
drivers/net/ethernet/renesas/ravb_main.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
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);
+ schedule_work(&priv->work);
+ return;
+ }
+
netif_tx_stop_all_queues(ndev);
/* Stop PTP Clock driver */
@@ -1907,7 +1913,7 @@ 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 +1923,9 @@ 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
