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Subject[patch 25/50] x86: fix setup of cyc2ns in tsc_64.c
-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Thomas Gleixner <tglx@linutronix.de>

upstream commit: b6db80ee1331e7beaeb91b4b3d946dd16c72e388

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 53d517cdbaac704352b3d0c10fecb99e0b54572e

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
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
arch/x86/kernel/tsc_64.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/tsc_64.c
+++ b/arch/x86/kernel/tsc_64.c
@@ -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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