x86: cdev lock_kernel() pushdown

Push the cdev lock_kernel() call down into the x86 msr and cpuid drivers.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

2 files changed, 29 insertions, 12 deletions

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index daff52a6224..71f1c2654be 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -33,6 +33,7 @@
 #include <linux/init.h>
 #include <linux/poll.h>
 #include <linux/smp.h>
+#include <linux/smp_lock.h>
 #include <linux/major.h>
 #include <linux/fs.h>
 #include <linux/smp_lock.h>
@@ -107,15 +108,23 @@ static ssize_t cpuid_read(struct file *file, char __user *buf,
 
 static int cpuid_open(struct inode *inode, struct file *file)
 {
-        unsigned int cpu = iminor(file->f_path.dentry->d_inode);
-        struct cpuinfo_x86 *c = &cpu_data(cpu);
-
-        if (cpu >= NR_CPUS || !cpu_online(cpu))
-                return -ENXIO;  /* No such CPU */
+        unsigned int cpu;
+        struct cpuinfo_x86 *c;
+        int ret = 0;
+        
+        lock_kernel();
+
+        cpu = iminor(file->f_path.dentry->d_inode);
+        if (cpu >= NR_CPUS || !cpu_online(cpu)) {
+                ret = -ENXIO;   /* No such CPU */
+                goto out;
+        }
+        c = &cpu_data(cpu);
         if (c->cpuid_level < 0)
-                return -EIO;    /* CPUID not supported */
-
-        return 0;
+                ret = -EIO;     /* CPUID not supported */
+out:
+        unlock_kernel();
+        return ret;
 }
 
 /*
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 1f3abe048e9..a153b3905f6 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -117,12 +117,20 @@ static int msr_open(struct inode *inode, struct file *file)
 {
         unsigned int cpu = iminor(file->f_path.dentry->d_inode);
         struct cpuinfo_x86 *c = &cpu_data(cpu);
+        int ret = 0;
 
-        if (cpu >= NR_CPUS || !cpu_online(cpu))
-                return -ENXIO;  /* No such CPU */
-        if (!cpu_has(c, X86_FEATURE_MSR))
-                return -EIO;    /* MSR not supported */
+        lock_kernel();
+        cpu = iminor(file->f_path.dentry->d_inode);
 
+        if (cpu >= NR_CPUS || !cpu_online(cpu)) {
+                ret = -ENXIO;   /* No such CPU */
+                goto out;
+        }
+        c = &cpu_data(cpu);
+        if (!cpu_has(c, X86_FEATURE_MSR))
+                ret = -EIO;     /* MSR not supported */
+out:
+        unlock_kernel();
         return 0;
 }