[PATCH 5.10] net: fec: remove .ndo_poll_controller to avoid deadlocks

From: Wei Fang <wei.fang@nxp.com>

commit c2e0c58b25a0a0c37ec643255558c5af4450c9f5 upstream.

There is a deadlock issue found in sungem driver, please refer to the
commit ac0a230f719b ("eth: sungem: remove .ndo_poll_controller to avoid
deadlocks"). The root cause of the issue is that netpoll is in atomic
context and disable_irq() is called by .ndo_poll_controller interface
of sungem driver, however, disable_irq() might sleep. After analyzing
the implementation of fec_poll_controller(), the fec driver should have
the same issue. Due to the fec driver uses NAPI for TX completions, the
.ndo_poll_controller is unnecessary to be implemented in the fec driver,
so fec_poll_controller() can be safely removed.

Fixes: 7f5c6addcdc0 ("net/fec: add poll controller function for fec nic")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://lore.kernel.org/r/20240511062009.652918-1-wei.fang@nxp.com (local)
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[Denis: minor fix to resolve merge conflict.]                                           
Signed-off-by: Denis Arefev <redacted>                                    
---
Backport fix for CVE-2024-38553
Link: https://nvd.nist.gov/vuln/detail/cve-2024-38553
---
 drivers/net/ethernet/freescale/fec_main.c | 26 -----------------------
 1 file changed, 26 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index a591ca0b3778..815062c23708 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c

@@ -3226,29 +3226,6 @@ fec_set_mac_address(struct net_device *ndev, void *p)
 	return 0;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-/**
- * fec_poll_controller - FEC Poll controller function
- * @dev: The FEC network adapter
- *
- * Polled functionality used by netconsole and others in non interrupt mode
- *
- */
-static void fec_poll_controller(struct net_device *dev)
-{
-	int i;
-	struct fec_enet_private *fep = netdev_priv(dev);
-
-	for (i = 0; i < FEC_IRQ_NUM; i++) {
-		if (fep->irq[i] > 0) {
-			disable_irq(fep->irq[i]);
-			fec_enet_interrupt(fep->irq[i], dev);
-			enable_irq(fep->irq[i]);
-		}
-	}
-}
-#endif
-
 static inline void fec_enet_set_netdev_features(struct net_device *netdev,
 	netdev_features_t features)
 {

@@ -3322,9 +3299,6 @@ static const struct net_device_ops fec_netdev_ops = {
 	.ndo_tx_timeout		= fec_timeout,
 	.ndo_set_mac_address	= fec_set_mac_address,
 	.ndo_do_ioctl		= fec_enet_ioctl,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= fec_poll_controller,
-#endif
 	.ndo_set_features	= fec_set_features,
 };
 

-- 
2.43.0