Re: [PATCH v2] can: usb: f81604: fix struct f81604_int_data size mismatch

On 24.08.2026 21:18:14, Ji-Ze Hong via B4 Relay wrote:
> From: "Ji-Ze Hong (Peter Hong)" <[email protected]>
>
> The struct f81604_int_data defines 9 bytes of interrupt data:
> - Byte 0: Status register (sr)
> - Byte 1: Interrupt register (isrc)
> - Byte 2: Interrupt enable register (ier)
> - Byte 3: Arbitration lost capture (alc)
> - Byte 4: Error code capture (ecc)
> - Byte 5: Error warning limit register (ewlr)
> - Byte 6: RX error counter (rxerr)
> - Byte 7: TX error counter (txerr)
> - Byte 8: Reserved (val)
>
> The hardware sends exactly 9 bytes for the interrupt endpoint.
> However, the struct was defined with __aligned(4) attribute which
> caused the compiler to pad the struct to 12 bytes.
>
> This causes a problem in f81604_read_int_callback() where the short
> URB check compares urb->actual_length against sizeof(*data). When
> sizeof(struct f81604_int_data) is 12 but the hardware only sends 9
> bytes, the check fails and valid interrupt messages are discarded.
>
> This results in the driver only being able to transmit once because
> the TX complete interrupt is never processed.
>
> Fix this by removing the __aligned(4) attribute so the struct size
> matches the actual hardware data size of 9 bytes.
>
> Fixes: 7299b1b39a25 ("can: usb: f81604: handle short interrupt urb messages properly")
> Cc: [email protected]
> Reported-by: Dynetrex, Admin <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Signed-off-by: Ji-Ze Hong (Peter Hong) <[email protected]>

Applied to linux-can.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
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