[Intel-gfx] [PATCH 01/10] drm/i915: Mark up protected uses of 'i915_request_completed'

[Andi Shyti]

Hi Chris,

> > > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> > > index 0b1a46a0d866..784c05ac5cca 100644
> > > --- a/drivers/gpu/drm/i915/i915_request.c
> > > +++ b/drivers/gpu/drm/i915/i915_request.c
> > > @@ -276,7 +276,7 @@ static void remove_from_engine(struct i915_request *rq)
> > >  
> > >  bool i915_request_retire(struct i915_request *rq)
> > >  {
> > > -     if (!i915_request_completed(rq))
> > > +     if (!__i915_request_is_complete(rq))
> > 
> > 
> > >               return false;
> > >  
> > >       RQ_TRACE(rq, "\n");
> > > @@ -342,8 +342,7 @@ void i915_request_retire_upto(struct i915_request *rq)
> > >       struct i915_request *tmp;
> > >  
> > >       RQ_TRACE(rq, "\n");
> > > -
> > > -     GEM_BUG_ON(!i915_request_completed(rq));
> > > +     GEM_BUG_ON(!__i915_request_is_complete(rq));
> > 
> > I might be a bit shallow, but where is the lock here?
> 
> This holds the request->context->timeline->mutex.
> 
> The locking is basically split between frontend/backend:
> 
>   construction/destruction - under the timeline->mutex
> 
>   execution - under the engine->active.lock (coordinates with
>               timeline->mutex)
> 
> At all other times, RCU protected access (using the SLAB_TYPESAFE_BY_RCU
> so approach with caution).

Right! Thanks!

Reviewed-by: Andi Shyti <andi.shyti at intel.com>

Andi