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Date:   Thu, 6 Jun 2019 15:13:00 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     pavel@ucw.cz
Cc:     linux-kernel@vger.kernel.org, Justin Chen <justinpopo6@gmail.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.19 189/276] iio: adc: ti-ads7950: Fix improper use of
 mlock
Message-ID: <20190606131300.GE27432@amd>
References: <20190530030523.133519668@linuxfoundation.org>
 <20190530030537.017297326@linuxfoundation.org>
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(stable removed from cc list)

> Indio->mlock is used for protecting the different iio device modes.
> It is currently not being used in this way. Replace the lock with
> an internal lock specifically used for protecting the SPI transfer
> buffer.
>=20
> Signed-off-by: Justin Chen <justinpopo6@gmail.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>  drivers/iio/adc/ti-ads7950.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
>=20

> @@ -277,6 +280,7 @@ static irqreturn_t ti_ads7950_trigger_handler(int irq=
, void *p)
>  	struct ti_ads7950_state *st =3D iio_priv(indio_dev);
>  	int ret;
> =20
> +	mutex_lock(&st->slock);
>  	ret =3D spi_sync(st->spi, &st->ring_msg);
>  	if (ret < 0)
>  		goto out;
> @@ -285,6 +289,7 @@ static irqreturn_t ti_ads7950_trigger_handler(int irq=
, void *p)
>  					   iio_get_time_ns(indio_dev));
> =20
>  out:
> +	mutex_unlock(&st->slock);
>  	iio_trigger_notify_done(indio_dev->trig);
> =20
>  	return IRQ_HANDLED;

Does trigger_handler run from interrupt context? Prototype suggests
so... If so, it can not really take mutexes...

Best regards,
								Pavel
							=09
--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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