[Intel-gfx] [PATCH 2/2] drm/i915: Removing polling for struct_mutex from vmap shrinker

[Tvrtko Ursulin]

On 10/01/2019 10:39, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-01-10 10:28:14)
>>
>> On 09/01/2019 16:42, Chris Wilson wrote:
>>> The wait-for-idle used from within the shrinker_lock_uninterruptible
>>> depends on the struct_mutex locking state being known and declared to
>>> i915_request_wait(). As it is conceivable that we reach the vmap
>>> notifier from underneath struct_mutex (and so keep on relying on the
>>> mutex_trylock_recursive), we should not blindly call i915_request_wait.
>>>
>>> In the process we can remove the dubious polling to acquire
>>> struct_mutex, and simply act, or not, on a successful trylock.
>>
>> Makes sense and removes the special casing. I only miss the historical
>> reference as to why did vmap notifier need this special handling?
> 
> Cargo culting. I copied the code I had for oom-notifier, thinking the
> heavier the hammer the better.

Go for it.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko