[PATCH net 3/3] net: stmmac: close the interface after failed hardware resume

[James Hilliard <james.hilliard1@gmail.com>]

System suspend disables NAPI and suspends phylink but retains the IRQs
and DMA resources. If hardware setup fails during resume, the interface
remains administratively up with NAPI still disabled. Closing it later
calls napi_disable() a second time and can hang indefinitely.

On hardware-setup failure, stop DMA and disable the MAC, then release the
suspended data path without repeating NAPI disable. Stop phylink directly
from its suspended state rather than restarting the link on hardware
which failed to resume. Drop the driver mutex before teardown, retaining
RTNL across cleanup and network-core close.

Close the netdev to detach the PHY, release its runtime-PM reference and
clear its administrative state. Reattach the now-down netdev so a later
open can allocate new resources and retry. Preserve the original resume
error and leave successful resume unchanged.

Fixes: 6896c2449a18 ("net: stmmac: Check stmmac_hw_setup() in stmmac_resume()")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 29 ++++++++++++++++-------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 44b59d0f56b5..87cb0978ed6a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4245,7 +4245,7 @@ static int stmmac_open(struct net_device *dev)
 	return ret;
 }
 
-static void __stmmac_release(struct net_device *dev)
+static void __stmmac_release(struct net_device *dev, bool napi_disabled)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 	u8 chan;
@@ -4258,7 +4258,9 @@ static void __stmmac_release(struct net_device *dev)
 	/* Stop and disconnect the PHY */
 	phylink_stop(priv->phylink);
 
-	stmmac_disable_all_queues(priv);
+	/* Suspend has already disabled NAPI when hardware resume fails. */
+	if (!napi_disabled)
+		stmmac_disable_all_queues(priv);
 
 	for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++)
 		hrtimer_cancel(&priv->dma_conf.tx_queue[chan].txtimer);
@@ -4297,7 +4299,7 @@ static int stmmac_release(struct net_device *dev)
 	if (device_may_wakeup(priv->device))
 		phylink_speed_down(priv->phylink, false);
 
-	__stmmac_release(dev);
+	__stmmac_release(dev, false);
 
 	stmmac_legacy_serdes_power_down(priv);
 	phylink_disconnect_phy(priv->phylink);
@@ -6174,7 +6176,7 @@ static int stmmac_change_mtu(struct net_device *dev, int new_mtu)
 			return PTR_ERR(dma_conf);
 		}
 
-		__stmmac_release(dev);
+		__stmmac_release(dev, false);
 
 		ret = __stmmac_open(dev, dma_conf);
 		if (ret) {
@@ -8356,10 +8358,7 @@ int stmmac_resume(struct device *dev)
 	ret = stmmac_hw_setup(ndev);
 	if (ret < 0) {
 		netdev_err(priv->dev, "%s: Hw setup failed\n", __func__);
-		stmmac_legacy_serdes_power_down(priv);
-		mutex_unlock(&priv->lock);
-		rtnl_unlock();
-		return ret;
+		goto error_stop_dma;
 	}
 
 	stmmac_init_timestamping(priv);
@@ -8386,6 +8385,20 @@ int stmmac_resume(struct device *dev)
 	netif_device_attach(ndev);
 
 	return 0;
+
+error_stop_dma:
+	stmmac_stop_all_dma(priv);
+	stmmac_mac_set(priv, priv->ioaddr, false);
+	mutex_unlock(&priv->lock);
+	/* Release the suspended data path before ndo_stop(), which must not
+	 * disable NAPI or free these resources a second time.
+	 */
+	__stmmac_release(ndev, true);
+	netif_close(ndev);
+	netif_device_attach(ndev);
+	rtnl_unlock();
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(stmmac_resume);
 

-- 
2.53.0