drm/i915: Allow late allocation of request for i915_add_request()

Request preallocation was added to i915_add_request() in order to
support the overlay. However, not all users care and can quite happily
ignore the failure to allocate the request as they will simply repeat
the request in the future.

By pushing the allocation down into i915_add_request(), we can then
remove some rather ugly error handling in the callers.

v2: Nullify request->file_priv otherwise we chase a garbage pointer
when retiring requests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 17 insertions, 27 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4be096068b35..771b8ba36e44 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1597,7 +1597,12 @@ i915_add_request(struct intel_ring_buffer *ring,
 		ring->gpu_caches_dirty = false;
 	}
 
-	BUG_ON(request == NULL);
+	if (request == NULL) {
+		request = kmalloc(sizeof(*request), GFP_KERNEL);
+		if (request == NULL)
+			return -ENOMEM;
+	}
+
 	seqno = i915_gem_next_request_seqno(ring);
 
 	/* Record the position of the start of the request so that
@@ -1608,8 +1613,10 @@ i915_add_request(struct intel_ring_buffer *ring,
 	request_ring_position = intel_ring_get_tail(ring);
 
 	ret = ring->add_request(ring, &seqno);
-	if (ret)
-	    return ret;
+	if (ret) {
+		kfree(request);
+		return ret;
+	}
 
 	trace_i915_gem_request_add(ring, seqno);
 
@@ -1619,6 +1626,7 @@ i915_add_request(struct intel_ring_buffer *ring,
 	request->emitted_jiffies = jiffies;
 	was_empty = list_empty(&ring->request_list);
 	list_add_tail(&request->list, &ring->request_list);
+	request->file_priv = NULL;
 
 	if (file) {
 		struct drm_i915_file_private *file_priv = file->driver_priv;
@@ -1859,14 +1867,8 @@ i915_gem_retire_work_handler(struct work_struct *work)
 	 */
 	idle = true;
 	for_each_ring(ring, dev_priv, i) {
-		if (ring->gpu_caches_dirty) {
-			struct drm_i915_gem_request *request;
-
-			request = kzalloc(sizeof(*request), GFP_KERNEL);
-			if (request == NULL ||
-			    i915_add_request(ring, NULL, request))
-			    kfree(request);
-		}
+		if (ring->gpu_caches_dirty)
+			i915_add_request(ring, NULL, NULL);
 
 		idle &= list_empty(&ring->request_list);
 	}
@@ -1913,25 +1915,13 @@ i915_gem_check_wedge(struct drm_i915_private *dev_priv,
 static int
 i915_gem_check_olr(struct intel_ring_buffer *ring, u32 seqno)
 {
-	int ret = 0;
+	int ret;
 
 	BUG_ON(!mutex_is_locked(&ring->dev->struct_mutex));
 
-	if (seqno == ring->outstanding_lazy_request) {
-		struct drm_i915_gem_request *request;
-
-		request = kzalloc(sizeof(*request), GFP_KERNEL);
-		if (request == NULL)
-			return -ENOMEM;
-
-		ret = i915_add_request(ring, NULL, request);
-		if (ret) {
-			kfree(request);
-			return ret;
-		}
-
-		BUG_ON(seqno != request->seqno);
-	}
+	ret = 0;
+	if (seqno == ring->outstanding_lazy_request)
+		ret = i915_add_request(ring, NULL, NULL);
 
 	return ret;
 }