x86, msr/cpuid: Register enough minors for the MSR and CPUID drivers (0b962d47) · Commits · 戴 / test

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>

arch/x86/kernel/cpuid.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

arch/x86/kernel/msr.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

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