On 03.03.2021 12:49:52, Torin Cooper-Bennun wrote:
> In peripherals, m_can_rx_handler is called with quota = 1 from an ISR
> context.
To be precise, it's a threaded Interrupt. Why not call the rx_handler
with a reasonable quota instead?
Marc
> If the M_CAN reports a high volume of errors, such as message
> loss due to heavy bus traffic, then error handling, which is prioritised
> in m_can_rx_handler, fills the quota immediately, and RX does not occur.
> This has been observed to cause an indefinite blocking of RX.
>
> The patch fixes this by ensuring that in peripherals, m_can_do_rx_poll
> is always called with a quota of at least 1, regardless of any errors
> handled.
>
> This has been tested with the TCAN4550 under heavy bus traffic; message
> loss is still detected correctly.
>
> Signed-off-by: Torin Cooper-Bennun <torin@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/net/can/m_can/m_can.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 3752520a7d4b..3ec42e613ca1 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -866,8 +866,14 @@ static int m_can_rx_handler(struct net_device *dev, int quota)
> if (irqstatus & IR_ERR_BUS_30X)
> work_done += m_can_handle_bus_errors(dev, irqstatus, psr);
>
> - if (irqstatus & IR_RF0N)
> - work_done += m_can_do_rx_poll(dev, (quota - work_done));
> + if (irqstatus & IR_RF0N) {
> + int rx_quota = quota - work_done;
> +
> + if (cdev->is_peripheral && (rx_quota <= 0))
> + rx_quota = 1;
> +
> + work_done += m_can_do_rx_poll(dev, rx_quota);
> + }
> end:
> return work_done;
> }
> --
> 2.30.1
>
>
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
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