Commit 060700b5 authored Aug 24, 2008 by Linus Torvalds Committed by H. Peter Anvin Aug 24, 2008

x86: do not enable TSC notifier if we don't need it



Impact: crash on non-TSC-equipped CPUs

Don't enable the TSC notifier if we *either*:

1. don't have a CPU, or
2. have a CPU with constant TSC.

In either of those cases, the notifier is either damaging (1) or useless(2).

From: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

parent 8735728e

arch/x86/kernel/tsc.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -325,6 +325,10 @@ static struct notifier_block time_cpufreq_notifier_block = {

		static int __init cpufreq_tsc(void)
		{
		if (!cpu_has_tsc)
		return 0;
		if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
		return 0;
		cpufreq_register_notifier(&time_cpufreq_notifier_block,
		CPUFREQ_TRANSITION_NOTIFIER);
		return 0;