x86: fix setup of cyc2ns in tsc_64.c (b6db80ee) · Commits · 戴 / test

When the TSC is calibrated against the PIT due to the nonavailability of PMTIMER/HPET or due to SMI interference then the setup of the per CPU cyc2ns variables is skipped. This is unlikely to happen but it would definitely render sched_clock() unusable. This was introduced with commit x86: scale cyc_2_nsec according to CPU frequency Update the per CPU cyc2ns variables in all exit pathes of tsc_calibrate. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org

arch/x86/kernel/tsc_64.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -227,14 +227,14 @@ void __init tsc_calibrate(void)
		/* hpet or pmtimer available ? */
		if (!hpet && !pm1 && !pm2) {
		printk(KERN_INFO "TSC calibrated against PIT\n");
		return;
		goto out;
		}

		/* Check, whether the sampling was disturbed by an SMI */
		if (tsc1 == ULONG_MAX \|\| tsc2 == ULONG_MAX) {
		printk(KERN_WARNING "TSC calibration disturbed by SMI, "
		"using PIT calibration result\n");
		return;
		goto out;
		}

		tsc2 = (tsc2 - tsc1) * 1000000L;
		@@ -255,6 +255,7 @@ void __init tsc_calibrate(void)

		tsc_khz = tsc2 / tsc1;

		out:
		for_each_possible_cpu(cpu)
		set_cyc2ns_scale(tsc_khz, cpu);
		}

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