disp: msm: sde: avoid duplicate fence create from client

SDE fence driver avoids duplicate fence creation if
fence timeline is not increased. This may lead to issue
if client closes the fence with failure ATOMIC_COMMIT.
SDE fence driver provides the closed fd node to subsequent
valid commit and leads to invalid state. This patch avoids
duplicate fence creation from crtc and connector object
instead of sde_fence.

Change-Id: Ic7b43762f0ad251fb20e42edb5f4d5f401790e14
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>

msm/sde/sde_crtc.c

@@ -5025,7 +5025,8 @@ static int sde_crtc_atomic_set_property(struct drm_crtc *crtc,
 	struct sde_crtc *sde_crtc;
 	struct sde_crtc_state *cstate;
 	int idx, ret;
-	uint64_t fence_fd;
+	uint64_t fence_user_fd;
+	uint64_t __user prev_user_fd;
 
 	if (!crtc || !state || !property) {
 		SDE_ERROR("invalid argument(s)\n");
@@ -5085,19 +5086,34 @@ static int sde_crtc_atomic_set_property(struct drm_crtc *crtc,
 		if (!val)
 			goto exit;
 
-		ret = _sde_crtc_get_output_fence(crtc, state, &fence_fd);
+		ret = copy_from_user(&prev_user_fd, (void __user *)val,
+				sizeof(uint64_t));
 		if (ret) {
-			SDE_ERROR("fence create failed rc:%d\n", ret);
+			SDE_ERROR("copy from user failed rc:%d\n", ret);
+			ret = -EFAULT;
 			goto exit;
 		}
 
-		ret = copy_to_user((uint64_t __user *)(uintptr_t)val, &fence_fd,
-				sizeof(uint64_t));
-		if (ret) {
-			SDE_ERROR("copy to user failed rc:%d\n", ret);
-			put_unused_fd(fence_fd);
-			ret = -EFAULT;
-			goto exit;
+		/*
+		 * client is expected to reset the property to -1 before
+		 * requesting for the release fence
+		 */
+		if (prev_user_fd == -1) {
+			ret = _sde_crtc_get_output_fence(crtc, state,
+					&fence_user_fd);
+			if (ret) {
+				SDE_ERROR("fence create failed rc:%d\n", ret);
+				goto exit;
+			}
+
+			ret = copy_to_user((uint64_t __user *)(uintptr_t)val,
+					&fence_user_fd, sizeof(uint64_t));
+			if (ret) {
+				SDE_ERROR("copy to user failed rc:%d\n", ret);
+				put_unused_fd(fence_user_fd);
+				ret = -EFAULT;
+				goto exit;
+			}
 		}
 		break;
 	default: