From: H. Peter Anvin <hpa@zytor.com>
Date: Tue, 15 Dec 2009 23:13:07 +0000 (-0800)
Subject: x86, msr/cpuid: Register enough minors for the MSR and CPUID drivers
X-Git-Tag: firefly_0821_release~11625^2~300
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d547e913ca2e6ec29510cca3e72a3cc430e53b89;p=firefly-linux-kernel-4.4.55.git

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

commit 0b962d473af32ec334df271b54ff4973cb2b4c73 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 6a52d4b36a30..f8590c509423 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -192,7 +192,8 @@ 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;
@@ -221,7 +222,7 @@ 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 6a3cefc7dda1..b42e63baa8e4 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -251,7 +251,7 @@ 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;
@@ -279,7 +279,7 @@ 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;
 }