[PATCH v8 3/7] drm/atomic: Allocate atomic_state at the beginning of atomic_ioctl

[Arun R Murthy <arun.r.murthy@intel.com>]

Move atomic_state allocation to the beginning of the atomic_ioctl
to accommodate drm_mode_atomic_err_code usage for returning error
code on failures.
As atomic state is required for drm_mode_atomic_err_code to store the
error codes.

v7: Reframe commit message (Suraj)
v8: Moved the clearing fence change to a different patch (Suraj/Louis)

Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index dc013a22bf265512a4fa1edf0ae90931ff0d35e6..3042e6c2616fb09403c13a8630c8819a39cf55d4 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1576,6 +1576,14 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
 		return -EOPNOTSUPP;
 
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
+	state->acquire_ctx = &ctx;
+	state->allow_modeset = !!(arg->flags & DRM_MODE_ATOMIC_ALLOW_MODESET);
+
 	/* disallow for userspace that has not enabled atomic cap (even
 	 * though this may be a bit overkill, since legacy userspace
 	 * wouldn't know how to call this ioctl)
@@ -1614,13 +1622,6 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 		return -EINVAL;
 	}
 
-	state = drm_atomic_state_alloc(dev);
-	if (!state)
-		return -ENOMEM;
-
-	drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
-	state->acquire_ctx = &ctx;
-	state->allow_modeset = !!(arg->flags & DRM_MODE_ATOMIC_ALLOW_MODESET);
 	state->plane_color_pipeline = file_priv->plane_color_pipeline;
 
 retry:
@@ -1719,6 +1720,13 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	}
 
 out:
+	/* Update the error code if any error to allow user handling it */
+	if (ret < 0 && arg->reserved) {
+		if (copy_to_user(error_code_ptr, &state->error_code,
+				 sizeof(state->error_code)))
+			return -EFAULT;
+	}
+
 	complete_signaling(dev, state, fence_state, num_fences, !ret);
 
 	if (ret == -EDEADLK) {

-- 
2.25.1