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Message-ID: <b3813a4e-3956-254c-a7cf-0fca65dc2cdd@linaro.org>
Date:   Sun, 24 Sep 2023 13:41:23 +0200
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Subject: Re: ERR_PTR(0) in a couple of places
To:     "Dr. David Alan Gilbert" <dave@treblig.org>,
        matthew.brost@intel.com, mgreer@animalcreek.com
Cc:     linux-kernel@vger.kernel.org, airlied@gmail.com,
        intel-gfx@lists.freedesktop.org
References: <ZQ+Fo9WKyGphwI8R@gallifrey>
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From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <ZQ+Fo9WKyGphwI8R@gallifrey>
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On 24/09/2023 02:41, 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);
> 
>   from f9d72092cb490 
> 
> 2) trf7970a
>   drivers/nfc/trf7970a.c : 896
> 
>       trf->ignore_timeout =
>          !cancel_delayed_work(&trf->timeout_work);
>       trf->rx_skb = ERR_PTR(0);

I would guess that code is relying on rx_skb being valid pointer or ERR
(if (!IS_ERR(...))).

Best regards,
Krzysztof