drm: Remove locking for legacy ioctls and DRM_UNLOCKED

Modern DRM drivers acquire ioctl locks by themselves. Legacy ioctls
for user-space mode setting used to acquire drm_global_mutex. After
removing the ioctl entry points, also remove the locking code. The only
legacy ioctl without global locking was VBLANK_WAIT, which has been
removed as well. Hence remove the related DRM_UNLOCKED flag.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: David Airlie <airlied@gmail.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231122122449.11588-12-tzimmermann@suse.de

drivers/gpu/drm/drm_ioc32.c

@@ -273,7 +273,7 @@ static int compat_drm_wait_vblank(struct file *file, unsigned int cmd,
 	req.request.type = req32.request.type;
 	req.request.sequence = req32.request.sequence;
 	req.request.signal = req32.request.signal;
-	err = drm_ioctl_kernel(file, drm_wait_vblank_ioctl, &req, DRM_UNLOCKED);
+	err = drm_ioctl_kernel(file, drm_wait_vblank_ioctl, &req, 0);
 
 	req32.reply.type = req.reply.type;
 	req32.reply.sequence = req.reply.sequence;

drivers/gpu/drm/drm_ioctl.c

@@ -596,7 +596,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 
 	DRM_IOCTL_DEF(DRM_IOCTL_FINISH, drm_noop, DRM_AUTH),
 
-	DRM_IOCTL_DEF(DRM_IOCTL_WAIT_VBLANK, drm_wait_vblank_ioctl, DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_WAIT_VBLANK, drm_wait_vblank_ioctl, 0),
 
 	DRM_IOCTL_DEF(DRM_IOCTL_UPDATE_DRAW, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 
@@ -729,28 +729,19 @@ long drm_ioctl_kernel(struct file *file, drm_ioctl_t *func, void *kdata,
 {
 	struct drm_file *file_priv = file->private_data;
 	struct drm_device *dev = file_priv->minor->dev;
-	int retcode;
+	int ret;
 
 	/* Update drm_file owner if fd was passed along. */
 	drm_file_update_pid(file_priv);
 
 	if (drm_dev_is_unplugged(dev))
 		return -ENODEV;
 
-	retcode = drm_ioctl_permit(flags, file_priv);
-	if (unlikely(retcode))
-		return retcode;
-
-	/* Enforce sane locking for modern driver ioctls. */
-	if (likely(!drm_core_check_feature(dev, DRIVER_LEGACY)) ||
-	    (flags & DRM_UNLOCKED))
-		retcode = func(dev, kdata, file_priv);
-	else {
-		mutex_lock(&drm_global_mutex);
-		retcode = func(dev, kdata, file_priv);
-		mutex_unlock(&drm_global_mutex);
-	}
-	return retcode;
+	ret = drm_ioctl_permit(flags, file_priv);
+	if (unlikely(ret))
+		return ret;
+
+	return func(dev, kdata, file_priv);
 }
 EXPORT_SYMBOL(drm_ioctl_kernel);
 

include/drm/drm_ioctl.h

@@ -109,17 +109,6 @@ enum drm_ioctl_flags {
 	 * This is equivalent to callers with the SYSADMIN capability.
 	 */
 	DRM_ROOT_ONLY		= BIT(2),
-	/**
-	 * @DRM_UNLOCKED:
-	 *
-	 * Whether &drm_ioctl_desc.func should be called with the DRM BKL held
-	 * or not. Enforced as the default for all modern drivers, hence there
-	 * should never be a need to set this flag.
-	 *
-	 * Do not use anywhere else than for the VBLANK_WAIT IOCTL, which is the
-	 * only legacy IOCTL which needs this.
-	 */
-	DRM_UNLOCKED		= BIT(4),
 	/**
 	 * @DRM_RENDER_ALLOW:
 	 *