can: skb: add skb CAN frame data length helpers

Add two helpers to retrieve the data length from CAN sk_buffs and prepare
the length information to be a uint16 value for the CAN XL support.

Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20220912170725.120748-3-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/dev/rx-offload.c b/drivers/net/can/dev/rx-offload.c
index ad8eb24..81ebf05 100644 (file)
--- a/drivers/net/can/dev/rx-offload.c
+++ b/drivers/net/can/dev/rx-offload.c
@@ -247,7 +247,7 @@ unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
        struct net_device *dev = offload->dev;
        struct net_device_stats *stats = &dev->stats;
        struct sk_buff *skb;
-       u8 len;
+       unsigned int len;
        int err;
 
        skb = __can_get_echo_skb(dev, idx, &len, frame_len_ptr);

diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
index f457c94..b896e1c 100644 (file)
--- a/drivers/net/can/dev/skb.c
+++ b/drivers/net/can/dev/skb.c
@@ -91,8 +91,8 @@ int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 EXPORT_SYMBOL_GPL(can_put_echo_skb);
 
 struct sk_buff *
-__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr,
-                  unsigned int *frame_len_ptr)
+__can_get_echo_skb(struct net_device *dev, unsigned int idx,
+                  unsigned int *len_ptr, unsigned int *frame_len_ptr)
 {
        struct can_priv *priv = netdev_priv(dev);
 
@@ -108,16 +108,12 @@ __can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr,
                 */
                struct sk_buff *skb = priv->echo_skb[idx];
                struct can_skb_priv *can_skb_priv = can_skb_prv(skb);
-               struct canfd_frame *cf = (struct canfd_frame *)skb->data;
 
                if (skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS)
                        skb_tstamp_tx(skb, skb_hwtstamps(skb));
 
                /* get the real payload length for netdev statistics */
-               if (cf->can_id & CAN_RTR_FLAG)
-                       *len_ptr = 0;
-               else
-                       *len_ptr = cf->len;
+               *len_ptr = can_skb_get_data_len(skb);
 
                if (frame_len_ptr)
                        *frame_len_ptr = can_skb_priv->frame_len;
@@ -147,7 +143,7 @@ unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx,
                              unsigned int *frame_len_ptr)
 {
        struct sk_buff *skb;
-       u8 len;
+       unsigned int len;
 
        skb = __can_get_echo_skb(dev, idx, &len, frame_len_ptr);
        if (!skb)

diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index 27ebfc2..ddffc2f 100644 (file)
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h
@@ -20,7 +20,8 @@ void can_flush_echo_skb(struct net_device *dev);
 int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
                     unsigned int idx, unsigned int frame_len);
 struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
-                                  u8 *len_ptr, unsigned int *frame_len_ptr);
+                                  unsigned int *len_ptr,
+                                  unsigned int *frame_len_ptr);
 unsigned int __must_check can_get_echo_skb(struct net_device *dev,
                                           unsigned int idx,
                                           unsigned int *frame_len_ptr);
@@ -113,4 +114,25 @@ static inline bool can_is_canfd_skb(const struct sk_buff *skb)
        return (skb->len == CANFD_MTU && cfd->len <= CANFD_MAX_DLEN);
 }
 
+/* get length element value from can[fd]_frame structure */
+static inline unsigned int can_skb_get_len_val(struct sk_buff *skb)
+{
+       const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+       return cfd->len;
+}
+
+/* get needed data length inside CAN frame for all frame types (RTR aware) */
+static inline unsigned int can_skb_get_data_len(struct sk_buff *skb)
+{
+       unsigned int len = can_skb_get_len_val(skb);
+       const struct can_frame *cf = (struct can_frame *)skb->data;
+
+       /* RTR frames have an actual length of zero */
+       if (can_is_can_skb(skb) && cf->can_id & CAN_RTR_FLAG)
+               return 0;
+
+       return len;
+}
+
 #endif /* !_CAN_SKB_H */