[Intel-gfx] [RFC 07/21] drm/i915: Ensure requests stick around during waits

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

For: VIZ-4377
Signed-off-by: John.C.Harrison at Intel.com
---
 drivers/gpu/drm/i915/i915_gem.c |   25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 2c33a83..53b48ad 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1360,9 +1360,11 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
 		return ret;
 
 	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+	i915_gem_request_reference(req);
 	mutex_unlock(&dev->struct_mutex);
 	ret = __wait_seqno(ring, seqno, reset_counter, true, NULL, file_priv);
 	mutex_lock(&dev->struct_mutex);
+	i915_gem_request_unreference(req);
 	if (ret)
 		return ret;
 
@@ -2825,6 +2827,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_wait *args = data;
 	struct drm_i915_gem_object *obj;
+	struct drm_i915_gem_request *req;
 	struct intel_engine_cs *ring = NULL;
 	unsigned reset_counter;
 	u32 seqno = 0;
@@ -2845,14 +2848,13 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	if (ret)
 		goto out;
 
-	if (obj->active) {
-		if (!obj->last_read_req)
-			goto out;
+	if (!obj->active || !obj->last_read_req)
+		goto out;
 
-		seqno = i915_gem_request_get_seqno(obj->last_read_req);
-		BUG_ON(seqno == 0);
-		ring = obj->ring;
-	}
+	req = obj->last_read_req;
+	seqno = i915_gem_request_get_seqno(req);
+	BUG_ON(seqno == 0);
+	ring = obj->ring;
 
 	/* Do this after OLR check to make sure we make forward progress polling
 	 * on this IOCTL with a timeout <=0 (like busy ioctl)
@@ -2864,10 +2866,15 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 
 	drm_gem_object_unreference(&obj->base);
 	reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+	i915_gem_request_reference(req);
 	mutex_unlock(&dev->struct_mutex);
 
-	return __wait_seqno(ring, seqno, reset_counter, true, &args->timeout_ns,
-			    file->driver_priv);
+	ret = __wait_seqno(ring, seqno, reset_counter, true, &args->timeout_ns,
+			   file->driver_priv);
+	mutex_lock(&dev->struct_mutex);
+	i915_gem_request_unreference(req);
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
 
 out:
 	drm_gem_object_unreference(&obj->base);
-- 
1.7.9.5