linux-kernel - Re: [PATCH] drm/shmem-helper: Fix locking for drm_gem_shmem_get_pages

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Message-ID: <c9805cb3-33c9-44ea-dab9-ec2f0624588f@suse.de>
Date:   Mon, 27 Feb 2023 10:20:37 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Asahi Lina <lina@...hilina.net>,
        Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org,
        Noralf Trønnes <noralf@...nnes.org>,
        linux-kernel@...r.kernel.org,
        Alyssa Rosenzweig <alyssa@...enzweig.io>, asahi@...ts.linux.dev
Subject: Re: [PATCH] drm/shmem-helper: Fix locking for
 drm_gem_shmem_get_pages_sgt()

Hi

Am 27.02.23 um 10:07 schrieb Asahi Lina:
> On 27/02/2023 17.04, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 27.02.23 um 08:55 schrieb Asahi Lina:
>>> On 27/02/2023 16.45, Thomas Zimmermann wrote:
>>>> Hi
>>>>
>>>> Am 25.02.23 um 22:51 schrieb Dmitry Osipenko:
>>>>> On 2/5/23 15:51, Asahi Lina wrote:
>>>>>> -EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
>>>>>> +EXPORT_SYMBOL(drm_gem_shmem_get_pages_sgt);
>>>>>
>>>>> Note it was a GPL symbol. I expect that all drm-shmem exports should be GPL.
>>>>
>>>> Right. I didn't notice that change, but it's probably not allowed. This
>>>> needs to be reverted to a GPL export
>>>
>>> I'm sorry, this was not intentional! I think I removed and re-added the
>>> export as part of making the wrapper and didn't notice it used to be _GPL...
>>>
>>> Do you want me to send a patch to add it back?
>>
>> Yes, please do. The Fixes tag is
>>
>>     Fixes: ddddedaa0db9 ("drm/shmem-helper: Fix locking for
>> drm_gem_shmem_get_pages_sgt()")
>>
>> This commit is in drm-misc-next-fixes. But the branch is closed already
>> as we're in the middle of the merge window. I think it's best to merge
>> the fix through drm-misc-fixes after the -rc1 hs been tagged.
> 
> Sent! I also noticed that there are quite a few other non-GPL exports in
> the file, with no real logic that I can see... I'm guessing most of
> those weren't intentional either?

I don't know. My guess is that some authors used EXPORT_SYMBOL() out of 
habit and others used EXPORT_SYMBOL_GPL() intentionally. And now, it's 
chaotic.

Even the file's initial commit 2194a63a818d contains both. I assume that 
some of the code has been taken from the DMA helpers, which date back 
much earlier with _GPL-only exports (see commit b9d474500546).

Best regards
Thomas

> 
> ~~ Lina

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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