netdev - Re: [PATCH 1/3] can: rcar_canfd: Fix IRQ storm on global fifo receive

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20221024153726.72avg6xbgzwyboms@pengutronix.de>
Date:   Mon, 24 Oct 2022 17:37:26 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Biju Das <biju.das.jz@...renesas.com>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Stefan Mätje <stefan.maetje@....eu>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Ulrich Hecht <uli+renesas@...nd.eu>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Rob Herring <robh@...nel.org>, linux-can@...r.kernel.org,
        netdev@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH 1/3] can: rcar_canfd: Fix IRQ storm on global fifo receive

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?

>   (for eg: can0 rx fifo interrupt enable is
>   disabled and can1 is triggering rx interrupt, the delay in rx_poll()
>   processing results in setting NAPIF_STATE_MISSED flag) leading to IRQ
>   storm.
> 
> This patch fixes the issue by checking irq is masked or not in
> irq handler and it masks the interrupt if it is unmasked.

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 |

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)