linux-kernel - Re: [PATCH] iio: inkern: fix a static checker error

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Date:   Mon, 24 Apr 2017 11:32:37 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Lars-Peter Clausen <lars@...afoo.de>,
        <linux-kernel@...r.kernel.org>
CC:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        <linux-iio@...r.kernel.org>
Subject: Re: [PATCH] iio: inkern: fix a static checker error

On 2017-04-20 23:13, Peter Rosin wrote:
> On 2017-04-20 23:12, Lars-Peter Clausen wrote:
>> On 04/20/2017 11:01 PM, Peter Rosin wrote:
>>> Avoid this smatch error:
>>> drivers/iio/inkern.c:751 iio_read_avail_channel_raw() error: double unlock 'mutex:&chan->indio_dev->info_exist_lock'
>>
>> Looks good, but it's not just the smatch error, this is a real issue. This
>> even seems to be a endless loop, always jumping back to err_unlock.
> 
> Yes, it should probably go to stable too...

Nope, not an endless loop, but I of course only noticed after sending
a v2 [1] which falsely stated just that. Ignore that v2 patch and take
this one instead, for the reasons stated in my followup [2] to that
message.

Involving stable is probably not needed either...

Cheers,
peda

[1] https://lkml.org/lkml/2017/4/24/179
[2] https://lkml.org/lkml/2017/4/24/221

>>>
>>> Fixes: 00c5f80c2fad ("iio: inkern: add helpers to query available values from channels")
>>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>>
>>> ---
>>>  drivers/iio/inkern.c | 4 +---
>>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
>>> index 7a13535dc3e9..a3941bade6a7 100644
>>> --- a/drivers/iio/inkern.c
>>> +++ b/drivers/iio/inkern.c
>>> @@ -750,11 +750,9 @@ int iio_read_avail_channel_raw(struct iio_channel *chan,
>>>  err_unlock:
>>>  	mutex_unlock(&chan->indio_dev->info_exist_lock);
>>>  
>>> -	if (ret >= 0 && type != IIO_VAL_INT) {
>>> +	if (ret >= 0 && type != IIO_VAL_INT)
>>>  		/* raw values are assumed to be IIO_VAL_INT */
>>>  		ret = -EINVAL;
>>> -		goto err_unlock;
>>> -	}
>>>  
>>>  	return ret;
>>>  }
>>>
>>
>