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Commit b6db80ee authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: fix setup of cyc2ns in tsc_64.c 



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 53d517cd

    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: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
parent 75d3bce2

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);

}