new helper: drm_ioctl_kernel()

drm_ioctl() guts sans copying the structure to/from userland
and parsing the ioctl cmd.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/gpu/drm/drm_ioctl.c

@@ -694,6 +694,32 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
  * structure.
  */
 
+long drm_ioctl_kernel(struct file *file, drm_ioctl_t *func, void *kdata,
+		      u32 flags)
+{
+	struct drm_file *file_priv = file->private_data;
+	struct drm_device *dev = file_priv->minor->dev;
+	int retcode;
+
+	if (drm_device_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 (!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;
+}
+
 /**
  * drm_ioctl - ioctl callback implementation for DRM drivers
  * @filp: file this ioctl is called on
@@ -762,10 +788,6 @@ long drm_ioctl(struct file *filp,
 		goto err_i1;
 	}
 
-	retcode = drm_ioctl_permit(ioctl->flags, file_priv);
-	if (unlikely(retcode))
-		goto err_i1;
-
 	if (ksize <= sizeof(stack_kdata)) {
 		kdata = stack_kdata;
 	} else {
@@ -784,16 +806,7 @@ long drm_ioctl(struct file *filp,
 	if (ksize > in_size)
 		memset(kdata + in_size, 0, ksize - in_size);
 
-	/* Enforce sane locking for modern driver ioctls. */
-	if (!drm_core_check_feature(dev, DRIVER_LEGACY) ||
-	    (ioctl->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);
-	}
-
+	retcode = drm_ioctl_kernel(filp, func, kdata, ioctl->flags);
 	if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
 		retcode = -EFAULT;
 

include/drm/drm_ioctl.h

@@ -172,6 +172,7 @@ struct drm_ioctl_desc {
 
 int drm_ioctl_permit(u32 flags, struct drm_file *file_priv);
 long drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
+long drm_ioctl_kernel(struct file *, drm_ioctl_t, void *, u32);
 #ifdef CONFIG_COMPAT
 long drm_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 #else