[Intel-gfx] [PATCH 1/3] drm/i915: Do not access rq->engine without a reference

[Ramalingam C <ramalingam.c@intel.com>]

From: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>

In i915_fence_get_driver_name(), user may not hold a
reference to rq->engine. Hence do not access it. Instead,
store required device private pointer in 'rq->i915' and use it.

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Suggested-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/i915/i915_request.c | 3 ++-
 drivers/gpu/drm/i915/i915_request.h | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 73d5195146b0..7f6998bf390c 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -60,7 +60,7 @@ static struct kmem_cache *slab_execute_cbs;
 
 static const char *i915_fence_get_driver_name(struct dma_fence *fence)
 {
-	return dev_name(to_request(fence)->engine->i915->drm.dev);
+	return dev_name(to_request(fence)->i915->drm.dev);
 }
 
 static const char *i915_fence_get_timeline_name(struct dma_fence *fence)
@@ -937,6 +937,7 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
 	rq->engine = ce->engine;
 	rq->ring = ce->ring;
 	rq->execution_mask = ce->engine->mask;
+	rq->i915 = ce->engine->i915;
 
 	ret = intel_timeline_get_seqno(tl, rq, &seqno);
 	if (ret)
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 28b1f9db5487..47041ec68df8 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -196,6 +196,8 @@ struct i915_request {
 	struct dma_fence fence;
 	spinlock_t lock;
 
+	struct drm_i915_private *i915;
+
 	/**
 	 * Context and ring buffer related to this request
 	 * Contexts are refcounted, so when this request is associated with a
-- 
2.20.1