Re: [Linaro-mm-sig] [PATCH v2 3/5] dma-buf: Move all dma-bufs to dynamic locking specification

[Dmitry Osipenko]

On 8/10/22 21:25, Christian König wrote:
> Am 10.08.22 um 19:49 schrieb Dmitry Osipenko:
>> On 8/10/22 14:30, Christian König wrote:
>>> Am 25.07.22 um 17:18 schrieb Dmitry Osipenko:
>>>> This patch moves the non-dynamic dma-buf users over to the dynamic
>>>> locking specification. The strict locking convention prevents deadlock
>>>> situation for dma-buf importers and exporters.
>>>>
>>>> Previously the "unlocked" versions of the dma-buf API functions weren't
>>>> taking the reservation lock and this patch makes them to take the lock.
>>>>
>>>> Intel and AMD GPU drivers already were mapping imported dma-bufs under
>>>> the held lock, hence the "locked" variant of the functions are added
>>>> for them and the drivers are updated to use the "locked" versions.
>>> In general "Yes, please", but that won't be that easy.
>>>
>>> You not only need to change amdgpu and i915, but all drivers
>>> implementing the map_dma_buf(), unmap_dma_buf() callbacks.
>>>
>>> Auditing all that code is a huge bunch of work.
>> Hm, neither of drivers take the resv lock in map_dma_buf/unmap_dma_buf.
>> It's easy to audit them all and I did it. So either I'm missing
>> something or it doesn't take much time to check them all. Am I really
>> missing something?
> 
> Ok, so this is only changing map/unmap now?

It also vmap/vunmap and attach/detach: In the previous patch I added the
_unlocked postfix to the func names and in this patch I made them all to
actually take the lock.

> In this case please separate this from the documentation change.

I'll factor out the doc in the v3.

> I would also drop the _locked postfix from the function name, just
> having _unlocked on all functions which are supposed to be called with
> the lock held should be sufficient.

Noted for the v3.

> Thanks for looking into this,
> Christian.

Thank you for the review.

-- 
Best regards,
Dmitry