[PATCH 2/2] drm/amdgpu: Fix use of interruptible waiting

[Michel Dänzer]

On 27/04/17 04:39 PM, Michel Dänzer wrote:
> On 27/04/17 04:19 AM, Alex Xie wrote:
>> Hi,
>>
>> I knew this is part of ioctl. And I intended to fix this interruptible
>> waiting in an ioctl.
> 
> It's by design, nothing that needs fixing in the case of an ioctl.
> 
> 
>> 1. The wait is short. There is not much benefit by interruptible
>> waiting.  The BO is a frame buffer BO. Are there many competitors to
>> lock this BO? If not, the wait is very short. This is my main reason to
>> change.
> 
> Irrelevant. If amdgpu_bo_reserve returns -EINTR, so will other functions
> down the line, and amdgpu_crtc_page_flip_target will have to propagate
> that anyway. So doing an uninterruptible wait will just delay the
> inevitable and delivery of the signal to userspace.

To be clear, I meant -ERESTARTSYS instead of -EINTR.


>> 2. In this function and caller functions, the error handling for such
>> interrupt is complicated and risky.
> 
> If you're concerned about the cascade of cleanup functions, let's just
> revert commit 0169b52ce575 ("drm/amdgpu: Refactor flip into prepare
> submit and submit. (v2)"). amdgpu_crtc_prepare_flip was split out to be
> used by DC, but DC is now using a DRM core atomic helper for flips and
> no longer using amdgpu_crtc_prepare_flip.
> 
> 


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer