[PATCH net-next v6 3/4] net: stmmac: release descriptor resources through priv->dma_conf on open failure

[Ding Hui]

From: Ding Hui <dinghui@xxxxxxxxxxx>

__stmmac_open() copies the temporary dma_conf passed by its callers
into the long-lived priv->dma_conf before setting up the hardware.
When the open fails after this copy, the descriptor resources now
belong to priv->dma_conf, but the error path returns without
releasing them and leaves stale pointers behind. The callers then
free the already-copied resources through the temporary dma_conf,
which aliases priv->dma_conf after the memcpy.

Fix this by making __stmmac_open() release the descriptor resources
through priv->dma_conf on failure. Callers of __stmmac_open() only
need to free the temporary dma_conf container in that case, while
failures before the call (PHY setup, serdes power up) still release
the resources through the temporary dma_conf via the existing
err_dma_resources path in stmmac_open().

stmmac_open() no longer jumps to the serdes label chain after
__stmmac_open() fails, as that chain would double-release the
descriptor resources and double-put the runtime PM reference, so the
cleanup is done inline instead.

The resource release is merged with the error unwinding that stops
the DMA engines and the MAC: failures after the hardware setup
first stop the DMA engines and the MAC, and then fall through to
the common init_error label that releases the descriptor resources,
while a stmmac_hw_setup() failure jumps to init_error directly as
the engines were never started.

Signed-off-by: Ding Hui <dinghui@xxxxxxxxxxx>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c    | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index a8401b04d79f..b093119e752f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4246,7 +4246,7 @@ static int __stmmac_open(struct net_device *dev,
 	ret = stmmac_hw_setup(dev);
 	if (ret < 0) {
 		netdev_err(priv->dev, "%s: Hw setup failed\n", __func__);
-		return ret;
+		goto init_error;
 	}
 
 	ret = stmmac_setup_ptp(priv);
@@ -4282,6 +4282,8 @@ static int __stmmac_open(struct net_device *dev,
 	stmmac_stop_all_dma(priv);
 	stmmac_mac_set(priv, priv->ioaddr, false);
 
+init_error:
+	free_dma_desc_resources(priv, &priv->dma_conf);
 	return ret;
 }
 
@@ -4314,8 +4316,13 @@ static int stmmac_open(struct net_device *dev)
 	}
 
 	ret = __stmmac_open(dev, dma_conf);
-	if (ret)
-		goto err_serdes;
+	if (ret) {
+		stmmac_legacy_serdes_power_down(priv);
+		phylink_disconnect_phy(priv->phylink);
+		pm_runtime_put(priv->device);
+		kfree(dma_conf);
+		return ret;
+	}
 
 	kfree(dma_conf);
 
@@ -4324,8 +4331,6 @@ static int stmmac_open(struct net_device *dev)
 
 	return ret;
 
-err_serdes:
-	stmmac_legacy_serdes_power_down(priv);
 err_disconnect_phy:
 	phylink_disconnect_phy(priv->phylink);
 err_runtime_pm:
@@ -6343,7 +6348,6 @@ static int stmmac_change_mtu(struct net_device *dev, int new_mtu)
 
 		ret = __stmmac_open(dev, dma_conf);
 		if (ret) {
-			free_dma_desc_resources(priv, dma_conf);
 			kfree(dma_conf);
 			netdev_err(priv->dev, "failed reopening the interface after MTU change\n");
 			return ret;
-- 
2.34.1