linux-kernel - [PATCH v3 03/14] net: axienet: Propagate failure of DMA descriptor setup

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Message-Id: <20200324132347.23709-4-andre.przywara@arm.com>
Date:   Tue, 24 Mar 2020 13:23:36 +0000
From:   Andre Przywara <andre.przywara@....com>
To:     "David S . Miller" <davem@...emloft.net>,
        Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
Cc:     Michal Simek <michal.simek@...inx.com>,
        Robert Hancock <hancock@...systems.ca>, netdev@...r.kernel.org,
        Russell King <rmk+kernel@....linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>
Subject: [PATCH v3 03/14] net: axienet: Propagate failure of DMA descriptor setup

When we fail allocating the DMA buffers in axienet_dma_bd_init(), we
report this error, but carry on with initialisation nevertheless.

This leads to a kernel panic when the driver later wants to send a
packet, as it uses uninitialised data structures.

Make the axienet_device_reset() routine return an error value, as it
contains the DMA buffer initialisation. Make sure we propagate the error
up the chain and eventually fail the driver initialisation, to avoid
relying on non-initialised buffers.

Signed-off-by: Andre Przywara <andre.przywara@....com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
---
 .../net/ethernet/xilinx/xilinx_axienet_main.c | 26 ++++++++++++++-----
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index d4c872425065..a25423e6fb36 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -437,9 +437,10 @@ static void axienet_setoptions(struct net_device *ndev, u32 options)
 	lp->options |= options;
 }
 
-static void __axienet_device_reset(struct axienet_local *lp)
+static int __axienet_device_reset(struct axienet_local *lp)
 {
 	u32 timeout;
+
 	/* Reset Axi DMA. This would reset Axi Ethernet core as well. The reset
 	 * process of Axi DMA takes a while to complete as all pending
 	 * commands/transfers will be flushed or completed during this
@@ -455,9 +456,11 @@ static void __axienet_device_reset(struct axienet_local *lp)
 		if (--timeout == 0) {
 			netdev_err(lp->ndev, "%s: DMA reset timeout!\n",
 				   __func__);
-			break;
+			return -ETIMEDOUT;
 		}
 	}
+
+	return 0;
 }
 
 /**
@@ -470,13 +473,17 @@ static void __axienet_device_reset(struct axienet_local *lp)
  * areconnected to Axi Ethernet reset lines, this in turn resets the Axi
  * Ethernet core. No separate hardware reset is done for the Axi Ethernet
  * core.
+ * Returns 0 on success or a negative error number otherwise.
  */
-static void axienet_device_reset(struct net_device *ndev)
+static int axienet_device_reset(struct net_device *ndev)
 {
 	u32 axienet_status;
 	struct axienet_local *lp = netdev_priv(ndev);
+	int ret;
 
-	__axienet_device_reset(lp);
+	ret = __axienet_device_reset(lp);
+	if (ret)
+		return ret;
 
 	lp->max_frm_size = XAE_MAX_VLAN_FRAME_SIZE;
 	lp->options |= XAE_OPTION_VLAN;
@@ -491,9 +498,11 @@ static void axienet_device_reset(struct net_device *ndev)
 			lp->options |= XAE_OPTION_JUMBO;
 	}
 
-	if (axienet_dma_bd_init(ndev)) {
+	ret = axienet_dma_bd_init(ndev);
+	if (ret) {
 		netdev_err(ndev, "%s: descriptor allocation failed\n",
 			   __func__);
+		return ret;
 	}
 
 	axienet_status = axienet_ior(lp, XAE_RCW1_OFFSET);
@@ -518,6 +527,8 @@ static void axienet_device_reset(struct net_device *ndev)
 	axienet_setoptions(ndev, lp->options);
 
 	netif_trans_update(ndev);
+
+	return 0;
 }
 
 /**
@@ -921,8 +932,9 @@ static int axienet_open(struct net_device *ndev)
 	 */
 	mutex_lock(&lp->mii_bus->mdio_lock);
 	axienet_mdio_disable(lp);
-	axienet_device_reset(ndev);
-	ret = axienet_mdio_enable(lp);
+	ret = axienet_device_reset(ndev);
+	if (ret == 0)
+		ret = axienet_mdio_enable(lp);
 	mutex_unlock(&lp->mii_bus->mdio_lock);
 	if (ret < 0)
 		return ret;
-- 
2.17.1