[PATCH 02/18] drm/i915: Allow i915_sw_fence_await_sw_fence() to allocate

[Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>]

In forthcoming patches, we want to be able to dynamically allocate the
wait_queue_t used whilst awaiting. This is more convenient if we extend
the i915_sw_fence_await_sw_fence() to perform the allocation for us if
we pass in a gfp mask rather than a preallocate struct.

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_gem_request.c |  2 +-
 drivers/gpu/drm/i915/i915_sw_fence.c    | 20 ++++++++++++++++++--
 drivers/gpu/drm/i915/i915_sw_fence.h    |  7 ++++++-
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 624d71bf4518..7496661b295e 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -678,7 +678,7 @@ void __i915_add_request(struct drm_i915_gem_request *request, bool flush_caches)
 				   &request->i915->drm.struct_mutex);
 	if (prev)
 		i915_sw_fence_await_sw_fence(&request->submit, &prev->submit,
-					     &request->submitq);
+					     &request->submitq, GFP_NOWAIT);
 
 	request->emitted_jiffies = jiffies;
 	request->previous_seqno = engine->last_submitted_seqno;
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 1e5cbc585ca2..0fe8b446ae84 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -135,6 +135,8 @@ static int i915_sw_fence_wake(wait_queue_t *wq, unsigned mode, int flags, void *
 	list_del(&wq->task_list);
 	__i915_sw_fence_complete(wq->private, key);
 	i915_sw_fence_put(wq->private);
+	if (wq->flags)
+		kfree(wq);
 	return 0;
 }
 
@@ -194,7 +196,7 @@ static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 
 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 				 struct i915_sw_fence *signaler,
-				 wait_queue_t *wq)
+				 wait_queue_t *wq, gfp_t gfp)
 {
 	unsigned long flags;
 	int pending;
@@ -206,8 +208,22 @@ int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 	if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
 		return -EINVAL;
 
+	pending = 0;
+	if (!wq) {
+		wq = kmalloc(sizeof(*wq), gfp);
+		if (!wq) {
+			if (!gfpflags_allow_blocking(gfp))
+				return -ENOMEM;
+
+			i915_sw_fence_wait(signaler);
+			return 0;
+		}
+
+		pending = 1;
+	}
+
 	INIT_LIST_HEAD(&wq->task_list);
-	wq->flags = 0;
+	wq->flags = pending;
 	wq->func = i915_sw_fence_wake;
 	wq->private = i915_sw_fence_get(fence);
 
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h
index 373141602ca4..d221df381ec2 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.h
+++ b/drivers/gpu/drm/i915/i915_sw_fence.h
@@ -45,7 +45,7 @@ void i915_sw_fence_commit(struct i915_sw_fence *fence);
 
 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 				 struct i915_sw_fence *after,
-				 wait_queue_t *wq);
+				 wait_queue_t *wq, gfp_t gfp);
 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 				  struct fence *dma,
 				  unsigned long timeout,
@@ -62,4 +62,9 @@ static inline bool i915_sw_fence_done(const struct i915_sw_fence *fence)
 	return atomic_read(&fence->pending) < 0;
 }
 
+static inline void i915_sw_fence_wait(struct i915_sw_fence *fence)
+{
+	wait_event(fence->wait, i915_sw_fence_done(fence));
+}
+
 #endif /* _I915_SW_FENCE_H_ */
-- 
2.9.3

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