linux-kernel - Re: [Intel-gfx] ERR_PTR(0) in a couple of places

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Date:   Mon, 25 Sep 2023 18:09:07 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Randy Dunlap <rdunlap@...radead.org>,
        Matthew Brost <matthew.brost@...el.com>,
        "Dr. David Alan Gilbert" <dave@...blig.org>
Cc:     krzysztof.kozlowski@...aro.org, airlied@...il.com,
        mgreer@...malcreek.com, intel-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Intel-gfx] ERR_PTR(0) in a couple of places

On Sun, 24 Sep 2023, Randy Dunlap <rdunlap@...radead.org> wrote:
> On 9/24/23 21:18, Matthew Brost wrote:
>> On Sun, Sep 24, 2023 at 12:41:07AM +0000, Dr. David Alan Gilbert wrote:
>>> Hi,
>>>   I randomly noticed there are a couple of places in the kernel that
>>> do
>>>    ERR_PTR(0);
>>>
>>> and thought that was odd - shouldn't those just be NULL's ?
>>>
>>> 1) i915
>>>   drivers/gpu/drm/i915/gt/uc/selftest_guc_multi_lrc.c : 47
>>>
>>>     if (i <= 1)
>>>       return ERR_PTR(0);
>> 
>> Yes, s/ERR_PTR(0)/ERR_PTR(NULL)/
>> 
>> Matt
>
> I agree with Dave's original suggestion since casting NULL isn't needed.

Yeah, s/ERR_PTR(0)/NULL/ would be my choice as well.

As a side note, I generally think it's better not to mix NULL and error
pointers in error return values for a function, because they're harder
to handle properly.

BR,
Jani.

>
>> 
>>>
>>>   from f9d72092cb490 
>>>
>>> 2) trf7970a
>>>   drivers/nfc/trf7970a.c : 896
>>>
>>>       trf->ignore_timeout =
>>>          !cancel_delayed_work(&trf->timeout_work);
>>>       trf->rx_skb = ERR_PTR(0);
>>>       trf7970a_send_upstream(trf);
>>>
>>>    from 1961843ceeca0
>>>
>>> Dave
>>> -- 
>>>  -----Open up your eyes, open up your mind, open up your code -------   
>>> / Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
>>> \        dave @ treblig.org |                               | In Hex /
>>>  \ _________________________|_____ http://www.treblig.org   |_______/

-- 
Jani Nikula, Intel