diff mbox series

[2/7] drm/syncobj: Do not allocate an array to store zeros when waiting

Message ID 20250106105521.53149-3-tursulin@igalia.com (mailing list archive)
State New
Headers show
Series A few drm_syncobj optimisations | expand

Commit Message

Tvrtko Ursulin Jan. 6, 2025, 10:55 a.m. UTC 
From: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>

When waiting on syncobjs the current code allocates a temporary array only
to fill it up with all zeros.

We can avoid that by relying on the allocated entry array already being
zero allocated.

For the timeline mode we can fetch the timeline point values as we
populate the entries array so also do not need this additional temporary
allocation.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
---
 drivers/gpu/drm/drm_syncobj.c | 39 ++++++++++++++---------------------
 1 file changed, 15 insertions(+), 24 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index d0d60c331df8..fd5ba6c89666 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1028,7 +1028,7 @@  static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
 }
 
 static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
-						  void __user *user_points,
+						  u64 __user *user_points,
 						  uint32_t count,
 						  uint32_t flags,
 						  signed long timeout,
@@ -1036,9 +1036,8 @@  static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 						  ktime_t *deadline)
 {
 	struct syncobj_wait_entry *entries;
-	struct dma_fence *fence;
-	uint64_t *points;
 	uint32_t signaled_count, i;
+	struct dma_fence *fence;
 
 	if (flags & (DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
 		     DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE)) {
@@ -1046,24 +1045,14 @@  static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 		lockdep_assert_none_held_once();
 	}
 
-	points = kmalloc_array(count, sizeof(*points), GFP_KERNEL);
-	if (points == NULL)
-		return -ENOMEM;
-
-	if (!user_points) {
-		memset(points, 0, count * sizeof(uint64_t));
-
-	} else if (copy_from_user(points, user_points,
-				  sizeof(uint64_t) * count)) {
-		timeout = -EFAULT;
-		goto err_free_points;
-	}
+	if (user_points &&
+	    !access_ok(user_points, count * sizeof(*user_points)))
+		return -EFAULT;
 
 	entries = kcalloc(count, sizeof(*entries), GFP_KERNEL);
-	if (!entries) {
-		timeout = -ENOMEM;
-		goto err_free_points;
-	}
+	if (!entries)
+		return -ENOMEM;
+
 	/* Walk the list of sync objects and initialize entries.  We do
 	 * this up-front so that we can properly return -EINVAL if there is
 	 * a syncobj with a missing fence and then never have the chance of
@@ -1074,9 +1063,14 @@  static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 		struct dma_fence *fence;
 
 		entries[i].task = current;
-		entries[i].point = points[i];
+		if (user_points &&
+		    __get_user(entries[i].point, user_points++)) {
+			timeout = -EFAULT;
+			goto cleanup_entries;
+		}
 		fence = drm_syncobj_fence_get(syncobjs[i]);
-		if (!fence || dma_fence_chain_find_seqno(&fence, points[i])) {
+		if (!fence ||
+		    dma_fence_chain_find_seqno(&fence, entries[i].point)) {
 			dma_fence_put(fence);
 			if (flags & (DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
 				     DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE)) {
@@ -1182,9 +1176,6 @@  static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
 	}
 	kfree(entries);
 
-err_free_points:
-	kfree(points);
-
 	return timeout;
 }