linux-kernel - Re: [PATCH 1/3] iio: dac: ad5592r: fix unbalanced mutex unlocks in ad5592r_read

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Message-ID: <872263d31269c590c34b46ccb6517ec26a330c18.camel@analog.com>
Date:   Mon, 6 Jul 2020 16:36:09 +0000
From:   "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
CC:     "jic23@...nel.org" <jic23@...nel.org>,
        "charles.stanhope@...il.com" <charles.stanhope@...il.com>
Subject: Re: [PATCH 1/3] iio: dac: ad5592r: fix unbalanced mutex unlocks in
 ad5592r_read_raw()

On Mon, 2020-07-06 at 14:02 +0300, Alexandru Ardelean wrote:
> [External]
> 
> There are 2 exit paths where the lock isn't held, but try to unlock the
> mutex when exiting. In these places we should just return from the
> function.
> 
> A neater approach would be to cleanup the ad5592r_read_raw(), but that
> would make this patch more difficult to backport to stable versions.
> 

I was a bit too hasty with this.
Apologies.
I'd like to add a tag here.

Reported-by: Charles Stanhope <charles.stanhope@...il.com>

> Fixes 56ca9db862bf3: ("iio: dac: Add support for the AD5592R/AD5593R
> ADCs/DACs")
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> ---
>  drivers/iio/dac/ad5592r-base.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-
> base.c
> index 5c4e5ff70380..cc4875660a69 100644
> --- a/drivers/iio/dac/ad5592r-base.c
> +++ b/drivers/iio/dac/ad5592r-base.c
> @@ -413,7 +413,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
>  			s64 tmp = *val * (3767897513LL / 25LL);
>  			*val = div_s64_rem(tmp, 1000000000LL, val2);
>  
> -			ret = IIO_VAL_INT_PLUS_MICRO;
> +			return IIO_VAL_INT_PLUS_MICRO;
>  		} else {
>  			int mult;
>  
> @@ -444,7 +444,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
>  		ret =  IIO_VAL_INT;
>  		break;
>  	default:
> -		ret = -EINVAL;
> +		return -EINVAL;
>  	}
>  
>  unlock: