x86: cpuid, msr: use inode mutex instead of big kernel lock

Instead of grabbing the BKL on seek, use the inode mutex in the style
of generic_file_llseek().

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 9 insertions, 5 deletions

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index bd82850e6519..af51ea8400b2 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
- *   
- *   Copyright 2000 H. Peter Anvin - All Rights Reserved
+ *
+ *   Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -45,9 +45,10 @@ static struct class *msr_class;
 
 static loff_t msr_seek(struct file *file, loff_t offset, int orig)
 {
-        loff_t ret = -EINVAL;
+        loff_t ret;
+        struct inode *inode = file->f_mapping->host;
 
-        lock_kernel();
+        mutex_lock(&inode->i_mutex);
         switch (orig) {
         case 0:
                 file->f_pos = offset;
@@ -56,8 +57,11 @@ static loff_t msr_seek(struct file *file, loff_t offset, int orig)
         case 1:
                 file->f_pos += offset;
                 ret = file->f_pos;
+                break;
+        default:
+                ret = -EINVAL;
         }
-        unlock_kernel();
+        mutex_unlock(&inode->i_mutex);
         return ret;
 }