[PATCH] drm/shmem-helpers: vunmap: Don't put pages for dma-buf

[Noralf Trønnes]

Den 25.02.2021 09.12, skrev Thomas Zimmermann:
> Hi
> 
> Am 24.02.21 um 18:14 schrieb Noralf Trønnes:
>>
>>
>> Den 19.02.2021 14.54, skrev Thomas Zimmermann:
>>> Hi
>>>
>>> Am 19.02.21 um 13:22 schrieb Noralf Trønnes:
>>>> dma-buf importing was reworked in commit 7d2cd72a9aa3
>>>> ("drm/shmem-helpers: Simplify dma-buf importing"). Before that commit
>>>> drm_gem_shmem_prime_import_sg_table() did set ->pages_use_count=1 and
>>>> drm_gem_shmem_vunmap_locked() could call drm_gem_shmem_put_pages()
>>>> unconditionally. Now without the use count set, put pages is called
>>>> also
>>>> on dma-bufs. Fix this by only putting pages if it's not imported.
>>>>
>>>> Fixes: 7d2cd72a9aa3 ("drm/shmem-helpers: Simplify dma-buf importing")
>>>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>>>> Cc: Thomas Zimmermann <tzimmermann at suse.de>
>>>> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
>>>
>>> Just when I saw the error. Nice. :)
>>>
>>> Acked-by: Thomas Zimmermann <tzimmermann at suse.de>
>>> Tested-by: Thomas Zimmermann <tzimmermann at suse.de>
>>>
>>
>> Should I apply this to drm-misc-fixes?
> 
> I think so. Ping me if you want me to add it.
> 

I'd appreciate if you could do it. I haven't applied a patch in almost a
year now and need to dig out my notes on how I do it. -fixes stuff is
for me a "hold my breath and hope I don't screw up anything" exercise.
Stressful :/

One day in the future I hope there's a green button I can push that
says: Merge patch to -fixes and make sure everything is OK. That would
be nice :)

Thanks,
Noralf.

> Best regards
> Thomas
> 
>>
>> Noralf.
>>
>>> For testing the GUD driver, you may also want to keep an eye at [1]
>>>
>>> Best regards
>>> Thomas
>>>
>>> [1]
>>> https://lore.kernel.org/dri-devel/02a45c11-fc73-1e5a-3839-30b080950af8@amd.com/T/#t
>>>
>>>
>>>
>>>> ---
>>>>    drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++---
>>>>    1 file changed, 4 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
>>>> b/drivers/gpu/drm/drm_gem_shmem_helper.c
>>>> index 9825c378dfa6..c8a6547a1757 100644
>>>> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
>>>> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
>>>> @@ -357,13 +357,14 @@ static void drm_gem_shmem_vunmap_locked(struct
>>>> drm_gem_shmem_object *shmem,
>>>>        if (--shmem->vmap_use_count > 0)
>>>>            return;
>>>>    -    if (obj->import_attach)
>>>> +    if (obj->import_attach) {
>>>>            dma_buf_vunmap(obj->import_attach->dmabuf, map);
>>>> -    else
>>>> +    } else {
>>>>            vunmap(shmem->vaddr);
>>>> +        drm_gem_shmem_put_pages(shmem);
>>>> +    }
>>>>          shmem->vaddr = NULL;
>>>> -    drm_gem_shmem_put_pages(shmem);
>>>>    }
>>>>      /*
>>>>
>>>
>