staging: gasket: top ioctl handler add __user annotations

Add __user annotation to gasket_core top-level ioctl handling pointer
arguments, for sparse checking.
Reported-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Zhongze Hu <frankhu@chromium.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gasket/gasket_core.c

@@ -14,6 +14,7 @@
 #include "gasket_page_table.h"
 #include "gasket_sysfs.h"
 
+#include <linux/compiler.h>
 #include <linux/delay.h>
 #include <linux/fs.h>
 #include <linux/init.h>
@@ -1781,6 +1782,7 @@ static long gasket_ioctl(struct file *filp, uint cmd, ulong arg)
 {
 	struct gasket_dev *gasket_dev;
 	const struct gasket_driver_desc *driver_desc;
+	void __user *argp = (void __user *)arg;
 	char path[256];
 
 	if (!filp)
@@ -1810,14 +1812,14 @@ static long gasket_ioctl(struct file *filp, uint cmd, ulong arg)
 		 * check_and_invoke_callback.
 		 */
 		if (driver_desc->ioctl_handler_cb)
-			return driver_desc->ioctl_handler_cb(filp, cmd, arg);
+			return driver_desc->ioctl_handler_cb(filp, cmd, argp);
 
 		gasket_log_error(
 			gasket_dev, "Received unknown ioctl 0x%x", cmd);
 		return -EINVAL;
 	}
 
-	return gasket_handle_ioctl(filp, cmd, arg);
+	return gasket_handle_ioctl(filp, cmd, argp);
 }
 
 int gasket_reset(struct gasket_dev *gasket_dev, uint reset_type)

drivers/staging/gasket/gasket_core.h

@@ -314,9 +314,12 @@ struct gasket_dev {
 	struct hlist_node legacy_hlist_node;
 };
 
+/* Type of the ioctl handler callback. */
+typedef long (*gasket_ioctl_handler_cb_t)
+		(struct file *file, uint cmd, void __user *argp);
 /* Type of the ioctl permissions check callback. See below. */
 typedef int (*gasket_ioctl_permissions_cb_t)(
-	struct file *filp, uint cmd, ulong arg);
+	struct file *filp, uint cmd, void __user *argp);
 
 /*
  * Device type descriptor.
@@ -550,7 +553,7 @@ struct gasket_driver_desc {
 	 * return -EINVAL. Should return an error status (either -EINVAL or
 	 * the error result of the ioctl being handled).
 	 */
-	long (*ioctl_handler_cb)(struct file *filp, uint cmd, ulong arg);
+	gasket_ioctl_handler_cb_t ioctl_handler_cb;
 
 	/*
 	 * device_status_cb: Callback to determine device health.