can_skb_get_frame_len(9)

can_skb_get_frame_len(9) — Kernel API Manual 🎀

✨ NAME ✨

okay so bestie, <pink>can_skb_get_frame_len</pink> is the function that calculates the CAN Frame length in bytes of a given skb. that's the whole job. main character energy only ✨

🌸 SYNOPSIS 🌸

unsigned int can_skb_get_frame_len (const struct sk_buff *skb );

🦋 ARGUMENTS 🦋

• skb — socket buffer of a CAN message. that's the input, bestie 🫶

💖 DESCRIPTION 💖

okay so here's the vibe: this does a rough calculation — bit stuffing is ignored, and the length in bits is rounded up to a length in bytes. no cap 🫶

💭 Rationale

the rationale is literally that this function is to be used for the BQL functions (netdev_sent_queue and netdev_completed_queue), which expect a value in bytes. just using skb->len is insufficient because it will return the constant value of CAN(FD)_MTU. doing the bit stuffing calculation would be too expensive in terms of computing resources for no noticeable gain. like, not worth it 💀

🧠 Remarks

the payload of CAN FD frames with the BRS flag are sent at a different bitrate. currently, the can-utils canbusload tool does not support CAN-FD yet, and so we could not run any benchmark to measure the impact. there might be possible improvement here 👀

👑 RETURN 👑

length in bytes. periodt 💅

🌈 SEE ALSO 🌈

• Kernel file ./drivers/net/can/dev/length.c — go peek, bestie 🦋

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source/version: ./drivers/net/can/dev · date: October 2026 · page: can_skb_get_frame_len(9) — byeee bestie, stay iconic 💅✨