[PATCH v2 2/2] drm/xe: Use the filelist from drm for ccs_mode change

[Lucas De Marchi]

On Tue, Oct 08, 2024 at 02:54:19PM +0000, Matthew Brost wrote:
>On Tue, Oct 08, 2024 at 01:06:28PM +0530, Balasubramani Vivekanandan wrote:
>> Drop the exclusive client count tracking and use the filelist from the
>> drm to track the active clients. This also ensures the clients created
>> internally by the driver won't block changing the ccs mode.
>>
>> Fixes: ce8c161cbad4 ("drm/xe: Add ref counting for xe_file")
>
>Is this really fixing anything. As far as I can tell nothing upstream
>opens a file internally (i.e. xe_file_open) is never called directly.

should fix this case:

	open()
	close()
			<---- race here
	change_ccs_mode()

because the close is not completely sync - the cleanup where the
previous number of clients is decremented is executed too late and
subject to a race fixed here.

I think the commit message needs to be improved to detail this fix.
The fact that internal clients don't end up changing the drm.filelist
is just a justification for why this should be ok wrt internal clients.

Lucas De Marchi