Re: [Intel-gfx] [PATCH] drm/i915/huc: fix leak of debug object in huc load fence on driver unload

["Ceraolo Spurio, Daniele" <daniele.ceraolospurio@intel.com>]

On 11/16/2022 5:29 PM, Brian Norris wrote:
> Hi Daniele,
>
> On Thu, Nov 10, 2022 at 04:56:51PM -0800, Daniele Ceraolo Spurio wrote:
>> The fence is always initialized in huc_init_early, but the cleanup in
>> huc_fini is only being run if HuC is enabled. This causes a leaking of
>> the debug object when HuC is disabled/not supported, which can in turn
>> trigger a warning if we try to register a new debug offset at the same
>> address on driver reload.
>>
>> To fix the issue, make sure to always run the cleanup code.
>>
>> Reported-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Reported-by: Brian Norris <briannorris@chromium.org>
>> Fixes: 27536e03271d ("drm/i915/huc: track delayed HuC load with a fence")
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Cc: Brian Norris <briannorris@chromium.org>
>> Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
>> Cc: John Harrison <John.C.Harrison@Intel.com>
>> ---
>>
>> Note: I didn't manage to repro the reported warning, but I did confirm
>> that we weren't correctly calling i915_sw_fence_fini and that this patch
>> fixes that.
> I *did* reproduce, and with this patch, I no longer reproduce. So:
>
> Tested-by: Brian Norris <briannorris@chromium.org>
>
> I see this differs very slightly from the draft version (which didn't
> work for me):
>
> https://lore.kernel.org/all/ac5fde11-c17d-8574-c938-c2278d53cf95@intel.com/
>
> so presumably that diff is the fix.

The extra diff makes the driver call the cleanup function even if HuC is 
disabled, while the draft version just fixed the cleanup function 
without making sure it was being called.

>
> Thanks a bunch!

Thanks for testing!

Daniele

>
> Brian
>
>>   drivers/gpu/drm/i915/gt/uc/intel_huc.c | 12 +++++++-----
>>   drivers/gpu/drm/i915/gt/uc/intel_uc.c  |  1 +
>>   2 files changed, 8 insertions(+), 5 deletions(-)