linux-kernel - Re: [PATCH] iio: adc: sun4i-gpadc-iio: fix unbalanced irq enable/disable

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Message-ID: <20170703211945.4vjnnjwl2lkcfr7u@flea>
Date:   Mon, 3 Jul 2017 23:19:45 +0200
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>
Cc:     jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
        pmeerw@...erw.net, wens@...e.org, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        thomas.petazzoni@...e-electrons.com
Subject: Re: [PATCH] iio: adc: sun4i-gpadc-iio: fix unbalanced irq
 enable/disable

On Mon, Jul 03, 2017 at 03:09:26PM +0200, Quentin Schulz wrote:
> When initializing interrupts, the devm_request_any_context_irq will
> enable them right away. An atomic flag was set in sun4i_irq_init and read
> in the interrupt handler to make sure no unwanted interrupts were
> handled. If an unwanted interrupt occurred, the handler would disable
> the irq and return IRQ_HANDLED. However, at the end of sun4i_irq_init,
> the irq would be disabled as well, resulting in an unbalanced enable
> (since there are more disables than enables, the code enabling the
> interrupt would never be called).
> 
> When reading the ADC or the temperature, the respective irq would be
> enabled in the read function and disabled in the irq handler. In the
> read function, we would wait for a completion (with a timeout) that will
> be set in the irq handler. However, if the completion is never set or if
> the wait for completion times out, the irq would not be disabled in the
> read function resulting in an unbalanced enable once the read function
> is called again (since there are 2+ enables for no disable).
> 
> Moving disable_irq from the irq handler to the read function get rid of
> these two cases of unbalanced enable.
> 
> Fixes: d1caa9905538 ("iio: adc: add support for Allwinner SoCs ADC")
> 
> Reported-by: Andreas Färber <afaerber@...e.de>
> Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>

Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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