On 24.10.2022 17:37:35, Marc Kleine-Budde wrote: > On 22.10.2022 09:15:01, Biju Das wrote: > > We are seeing IRQ storm on global receive IRQ line under heavy CAN > > bus load conditions with both CAN channels are enabled. > > > > Conditions: > > The global receive IRQ line is shared between can0 and can1, either > > of the channels can trigger interrupt while the other channel irq > > line is disabled(rfie). > > When global receive IRQ interrupt occurs, we mask the interrupt in > > irqhandler. Clearing and unmasking of the interrupt is happening in > > rx_poll(). There is a race condition where rx_poll unmask the > > interrupt, but the next irq handler does not mask the irq due to > > NAPIF_STATE_MISSED flag. > > Why does this happen? Is it a problem that you call > rcar_canfd_handle_global_receive() for a channel that has the IRQs > actually disabled in hardware? Can you check if the IRQ is active _and_ enabled before handling the IRQ on a particular channel? A more clearer approach would be to get rid of the global interrupt handlers at all. If the hardware only given 1 IRQ line for more than 1 channel, the driver would register an IRQ handler for each channel (with the shared attribute). The IRQ handler must check, if the IRQ is pending and enabled. If not return IRQ_NONE, otherwise handle and return IRQ_HANDLED. Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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