From 20613f24bcd1cbfb08e64f0bb00c44481313b448 Mon Sep 17 00:00:00 2001
From: Jonathan Corbet <corbet@lwn.net>
Date: Thu, 15 May 2008 16:24:25 -0600
Subject: usbcore: cdev lock_kernel() pushdown

usb_open() is protected by a down_read(&minor_rwsem), but I'm not sure I
trust it to protect everything including subsidiary open() functions.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
---
 drivers/usb/core/file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/core/file.c b/drivers/usb/core/file.c
index 8133c99c6c5..c6a95395e52 100644
--- a/drivers/usb/core/file.c
+++ b/drivers/usb/core/file.c
@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/rwsem.h>
+#include <linux/smp_lock.h>
 #include <linux/usb.h>
 
 #include "usb.h"
@@ -33,6 +34,7 @@ static int usb_open(struct inode * inode, struct file * file)
 	int err = -ENODEV;
 	const struct file_operations *old_fops, *new_fops = NULL;
 
+	lock_kernel();
 	down_read(&minor_rwsem);
 	c = usb_minors[minor];
 
@@ -51,6 +53,7 @@ static int usb_open(struct inode * inode, struct file * file)
 	fops_put(old_fops);
  done:
 	up_read(&minor_rwsem);
+	unlock_kernel();
 	return err;
 }
 
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