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authorVincent Mailhol <mailhol.vincent@wanadoo.fr>2021-12-07 15:15:31 +0300
committerMarc Kleine-Budde <mkl@pengutronix.de>2022-01-05 14:09:05 +0300
commitcc4b08c31b5c51352f258032cc65e884b3e61e6a (patch)
tree1ff8f441190194792f5da507b6952d1ced79ae36 /drivers/net/can/c_can
parent8e674ca74244eac1cd85c6e9a89b588a03c55ff7 (diff)
downloadlinux-cc4b08c31b5c51352f258032cc65e884b3e61e6a.tar.xz
can: do not increase tx_bytes statistics for RTR frames
The actual payload length of the CAN Remote Transmission Request (RTR) frames is always 0, i.e. no payload is transmitted on the wire. However, those RTR frames still use the DLC to indicate the length of the requested frame. As such, net_device_stats::tx_bytes should not be increased when sending RTR frames. The function can_get_echo_skb() already returns the correct length, even for RTR frames (c.f. [1]). However, for historical reasons, the drivers do not use can_get_echo_skb()'s return value and instead, most of them store a temporary length (or dlc) in some local structure or array. Using the return value of can_get_echo_skb() solves the issue. After doing this, such length/dlc fields become unused and so this patch does the adequate cleaning when needed. This patch fixes all the CAN drivers. Finally, can_get_echo_skb() is decorated with the __must_check attribute in order to force future drivers to correctly use its return value (else the compiler would emit a warning). [1] commit ed3320cec279 ("can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames") Link: https://lore.kernel.org/all/20211207121531.42941-6-mailhol.vincent@wanadoo.fr Cc: Nicolas Ferre <nicolas.ferre@microchip.com> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> Cc: Ludovic Desroches <ludovic.desroches@microchip.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Jernej Skrabec <jernej.skrabec@gmail.com> Cc: Yasushi SHOJI <yashi@spacecubics.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Stephane Grosjean <s.grosjean@peak-system.com> Cc: Andreas Larsson <andreas@gaisler.com> Tested-by: Jimmy Assarsson <extja@kvaser.com> # kvaser Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Acked-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2 Tested-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2 [mkl: add conversion for grcan] Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'drivers/net/can/c_can')
-rw-r--r--drivers/net/can/c_can/c_can.h1
-rw-r--r--drivers/net/can/c_can/c_can_main.c7
2 files changed, 2 insertions, 6 deletions
diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
index 08b6efa7a1a7..bd2f6dc01194 100644
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
@@ -211,7 +211,6 @@ struct c_can_priv {
struct c_can_raminit raminit_sys; /* RAMINIT via syscon regmap */
void (*raminit)(const struct c_can_priv *priv, bool enable);
u32 comm_rcv_high;
- u32 dlc[];
};
struct net_device *alloc_c_can_dev(int msg_obj_num);
diff --git a/drivers/net/can/c_can/c_can_main.c b/drivers/net/can/c_can/c_can_main.c
index 29e91804d81c..faa217f26771 100644
--- a/drivers/net/can/c_can/c_can_main.c
+++ b/drivers/net/can/c_can/c_can_main.c
@@ -477,7 +477,6 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
* transmit as we might race against do_tx().
*/
c_can_setup_tx_object(dev, IF_TX, frame, idx);
- priv->dlc[idx] = frame->len;
can_put_echo_skb(skb, dev, idx, 0);
obj = idx + priv->msg_obj_tx_first;
c_can_object_put(dev, IF_TX, obj, cmd);
@@ -742,8 +741,7 @@ static void c_can_do_tx(struct net_device *dev)
* NAPI. We are not transmitting.
*/
c_can_inval_tx_object(dev, IF_NAPI, obj);
- can_get_echo_skb(dev, idx, NULL);
- bytes += priv->dlc[idx];
+ bytes += can_get_echo_skb(dev, idx, NULL);
pkts++;
}
@@ -1227,8 +1225,7 @@ struct net_device *alloc_c_can_dev(int msg_obj_num)
struct c_can_priv *priv;
int msg_obj_tx_num = msg_obj_num / 2;
- dev = alloc_candev(struct_size(priv, dlc, msg_obj_tx_num),
- msg_obj_tx_num);
+ dev = alloc_candev(sizeof(*priv), msg_obj_tx_num);
if (!dev)
return NULL;