linux-kernel - Re: [PATCH] genirq: warn on inconstent flags and flow handler

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Message-ID: <CAGVrzca27LfOLmOaVGMuXpch1U_nZf01qPhu3Oj+dWz0Ztxofg@mail.gmail.com>
Date:	Tue, 1 Jul 2014 11:56:53 -0700
From:	Florian Fainelli <f.fainelli@...il.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Brian Norris <computersforpeace@...il.com>,
	Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH] genirq: warn on inconstent flags and flow handler

2014-06-13 9:36 GMT-07:00 Florian Fainelli <f.fainelli@...il.com>:
> It is currently possible for a generic irq chip driver to set IRQ_LEVEL
> and have its irq flow handler be handle_edge_irq. Setting IRQ_LEVEL in
> such a case does not make sense, and will actually prevent e.g: the
> software resend logic from kicking, and potential other problems too.
>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
> Thomas,
>
> This is the change I mentioned to you on the #mipslinux IRC channel,
> let me know if you feel like this should be somewhere else, AFAICT
> this should not slow things down.

Thomas, Jason, is this something you are willing to accept?
irq_modify_status() should not be called in a hot-path as far as I
audited the code, but let me know if you prefer another solution (like
propagating an error code from irq_modify_status()).

Thanks!

>
> Thanks!
>
>  kernel/irq/chip.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index a2b28a2fd7b1..939ae1283ec9 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -749,8 +749,13 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
>                 irqd_set(&desc->irq_data, IRQD_PER_CPU);
>         if (irq_settings_can_move_pcntxt(desc))
>                 irqd_set(&desc->irq_data, IRQD_MOVE_PCNTXT);
> -       if (irq_settings_is_level(desc))
> +       if (irq_settings_is_level(desc)) {
> +               /* Setting IRQD_LEVEL does not make sense on non-level
> +                * sensitive interrupts
> +                */
> +               WARN_ON(desc->handle_irq != handle_level_irq);
>                 irqd_set(&desc->irq_data, IRQD_LEVEL);
> +       }
>
>         irqd_set(&desc->irq_data, irq_settings_get_trigger_mask(desc));
>
> --
> 1.9.1
>



-- 
Florian
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