drm/i915: Allow sharing the idle-barrier from other kernel requests

By placing our idle-barriers in the i915_active fence tree, we expose
those for reuse by other components that are issuing requests along the
kernel_context. Reusing the proto-barrier active_node is perfectly fine
as the new request implies a context-switch, and so an opportune point
to run the idle-barrier. However, the proto-barrier is not equivalent
to a normal active_node and care must be taken to avoid dereferencing the
ERR_PTR used as its request marker.

v2: Comment the more egregious cheek
v3: A glossary!

Reported-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: ce476c80b8bf ("drm/i915: Keep contexts pinned until after the next kernel context switch")
Fixes: a9877da2d629 ("drm/i915/oa: Reconfigure contexts on the fly")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190802100015.1281-1-chris@chris-wilson.co.uk

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_active.h b/drivers/gpu/drm/i915/i915_active.h
index ba68b077ec6c..566336c99ed7 100644
--- a/drivers/gpu/drm/i915/i915_active.h
+++ b/drivers/gpu/drm/i915/i915_active.h
@@ -413,6 +413,6 @@ static inline void i915_active_fini(struct i915_active *ref) { }
 int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
 					    struct intel_engine_cs *engine);
 void i915_active_acquire_barrier(struct i915_active *ref);
-void i915_request_add_barriers(struct i915_request *rq);
+void i915_request_add_active_barriers(struct i915_request *rq);
 
 #endif /* _I915_ACTIVE_H_ */