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, 3 insertions, 4 deletions

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index c10ebc4b8e4b..288e7a6598ac 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -62,9 +62,9 @@ static void cpuid_smp_cpuid(void *cmd_block)
 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
 {
         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;
@@ -77,8 +77,7 @@ static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
         default:
                 ret = -EINVAL;
         }
-
-        unlock_kernel();
+        mutex_unlock(&inode->i_mutex);
         return ret;
 }