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

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

[Wei Fang]

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>
---
 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 8bd213da8fb6..a72d8a2eb0b3 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -3674,29 +3674,6 @@ 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)
 {
@@ -4003,9 +3980,6 @@ static const struct net_device_ops fec_netdev_ops = {
 	.ndo_tx_timeout		= fec_timeout,
 	.ndo_set_mac_address	= fec_set_mac_address,
 	.ndo_eth_ioctl		= phy_do_ioctl_running,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= fec_poll_controller,
-#endif
 	.ndo_set_features	= fec_set_features,
 	.ndo_bpf		= fec_enet_bpf,
 	.ndo_xdp_xmit		= fec_enet_xdp_xmit,
-- 
2.34.1

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

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sat, 11 May 2024 14:20:09 +0800 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [net] net: fec: remove .ndo_poll_controller to avoid deadlocks
    https://git.kernel.org/netdev/net/c/c2e0c58b25a0

You are awesome, thank you!
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