netdev - [net-next 09/12] can: mcp251xfd: mcp251xfd_hw_rx_obj_to_skb(): don't copy data for RTR CAN frames in RX-path

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Message-Id: <20210127092227.2775573-10-mkl@pengutronix.de>
Date:   Wed, 27 Jan 2021 10:22:24 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [net-next 09/12] can: mcp251xfd: mcp251xfd_hw_rx_obj_to_skb(): don't copy data for RTR CAN frames in RX-path

In Classical CAN there are RTR frames. RTR frames have the RTR bit set, may
have a dlc != 0, but contain no data.

This patch changes the RX-path to no copy any data for RTR frames, so that the
data field in the CAN frame stays 0x0.

Link: https://lore.kernel.org/r/20210114153448.1506901-4-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index aa992e71d787..92816be4f3d4 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -1474,7 +1474,8 @@ mcp251xfd_hw_rx_obj_to_skb(const struct mcp251xfd_priv *priv,
 						 hw_rx_obj->flags));
 	}
 
-	memcpy(cfd->data, hw_rx_obj->data, cfd->len);
+	if (!(hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_RTR))
+		memcpy(cfd->data, hw_rx_obj->data, cfd->len);
 }
 
 static int
-- 
2.29.2