[PATCH] staging/android: refactor SYNC_IOC_FILE_INFO

[Maarten Lankhorst]

Op 03-03-16 om 15:34 schreef Gustavo Padovan:
> From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
>
> Change SYNC_IOC_FILE_INFO behaviour to avoid future API breaks and
> optimize buffer
>
> Now num_fences can be filled by the caller to inform how many fences it
> wants to retrieve from the kernel. If the num_fences passed is greater
> than zero info->sync_fence_info should point to a buffer with enough space
> to fit all fences.
>
> However if num_fences passed to the kernel is 0, the kernel will reply
> with number of fences of the sync_file.
>
> Sending first an ioctl with num_fences = 0 can optimize buffer allocation,
> in a first call with num_fences = 0 userspace will receive the actual
> number of fences in the num_fences filed.
>
> Then it can allocate a buffer with the correct size on sync_fence_info and
> call SYNC_IOC_FILE_INFO again, but now with the actual value of num_fences
> in the sync_file.
>
> Also, info->sync_fence_info was converted to __u64 pointer to prevent
> 32bit compatibility issues.
For this patch and 6/6:

Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>