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From:   Andre Przywara <andre.przywara@arm.com>
To:     "David S . Miller" <davem@davemloft.net>,
        Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Cc:     Michal Simek <michal.simek@xilinx.com>,
        Robert Hancock <hancock@sedsystems.ca>, netdev@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 04/14] net: axienet: Improve DMA error handling
Date:   Fri, 10 Jan 2020 11:54:05 +0000
Message-Id: <20200110115415.75683-5-andre.przywara@arm.com>
In-Reply-To: <20200110115415.75683-1-andre.przywara@arm.com>
References: <20200110115415.75683-1-andre.przywara@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Since 0 is a valid DMA address, we cannot use the physical address to
check whether a TX descriptor is valid and is holding a DMA mapping.

Use the "cntrl" member of the descriptor to make this decision, as it
contains at least the length of the buffer, so 0 points to an
uninitialised buffer.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 7e90044cf2d9..ec5d01adc1d5 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -570,7 +570,7 @@ static void axienet_start_xmit_done(struct net_device *ndev)
 				DMA_TO_DEVICE);
 		if (cur_p->skb)
 			dev_consume_skb_irq(cur_p->skb);
-		/*cur_p->phys = 0;*/
+		cur_p->cntrl = 0;
 		cur_p->app0 = 0;
 		cur_p->app1 = 0;
 		cur_p->app2 = 0;
@@ -1557,7 +1557,7 @@ static void axienet_dma_err_handler(unsigned long data)
 
 	for (i = 0; i < lp->tx_bd_num; i++) {
 		cur_p = &lp->tx_bd_v[i];
-		if (cur_p->phys)
+		if (cur_p->cntrl)
 			dma_unmap_single(ndev->dev.parent, cur_p->phys,
 					 (cur_p->cntrl &
 					  XAXIDMA_BD_CTRL_LENGTH_MASK),
-- 
2.17.1