x86, msr/cpuid: Register enough minors for the MSR and CPUID drivers

register_chrdev() hardcodes registering 256 minors, presumably to
avoid breaking old drivers.  However, we need to register enough
minors so that we have all possible CPUs.

checkpatch warns on this patch, but the patch is correct: NR_CPUS here
is a static *upper bound* on the *maximum CPU index* (not *number of
CPUs!*) and that is what we want.

Reported-and-tested-by: Russ Anderson <rja@sgi.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <tip-*@git.kernel.org>

2 files changed, 5 insertions, 4 deletions

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 7ef24a796992..cb27fd6136c9 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -187,7 +187,8 @@ static int __init cpuid_init(void)
         int i, err = 0;
         i = 0;
 
-        if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
+        if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS,
+                              "cpu/cpuid", &cpuid_fops)) {
                 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
                        CPUID_MAJOR);
                 err = -EBUSY;
@@ -216,7 +217,7 @@ out_class:
         }
         class_destroy(cpuid_class);
 out_chrdev:
-        unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
+        __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
 out:
         return err;
 }
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 572b07eee3f4..4bd93c9b2b27 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -246,7 +246,7 @@ static int __init msr_init(void)
         int i, err = 0;
         i = 0;
 
-        if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
+        if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
                 printk(KERN_ERR "msr: unable to get major %d for msr\n",
                        MSR_MAJOR);
                 err = -EBUSY;
@@ -274,7 +274,7 @@ out_class:
                 msr_device_destroy(i);
         class_destroy(msr_class);
 out_chrdev:
-        unregister_chrdev(MSR_MAJOR, "cpu/msr");
+        __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
 out:
         return err;
 }