diff options
author | Peter Zijlstra <[email protected]> | 2014-06-24 14:48:19 +0200 |
---|---|---|
committer | Ingo Molnar <[email protected]> | 2014-07-02 08:33:47 +0200 |
commit | 3896c329df8092661dac80f55a8c3f60136fd61a (patch) | |
tree | 02b53e8b429cd1a794a85cabc37d5181fe4d0e9c | |
parent | 16874b2cb867d3eb63ed838f2847143e11556708 (diff) |
x86, tsc: Fix cpufreq lockup
Mauro reported that his AMD X2 using the powernow-k8 cpufreq driver
locked up when doing cpu hotplug.
Because we called set_cyc2ns_scale() from the time_cpufreq_notifier()
unconditionally, it gets called multiple times for each freq change,
instead of only the once, when the tsc_khz value actually changes.
Because it gets called more than once, we run out of cyc2ns data slots
and stall, waiting for a free one, but because we're half way offline,
there's no consumers to free slots.
By placing the call inside the condition that actually changes tsc_khz
we avoid superfluous calls and avoid the problem.
Reported-by: Mauro <[email protected]>
Tested-by: Mauro <[email protected]>
Fixes: 20d1c86a5776 ("sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs")
Cc: <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Bin Gao <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mika Westerberg <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Stefani Seibold <[email protected]>
Cc: [email protected]
Signed-off-by: Peter Zijlstra <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
-rw-r--r-- | arch/x86/kernel/tsc.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 57e5ce126d5a..ea030319b321 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -920,9 +920,9 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); if (!(freq->flags & CPUFREQ_CONST_LOOPS)) mark_tsc_unstable("cpufreq changes"); - } - set_cyc2ns_scale(tsc_khz, freq->cpu); + set_cyc2ns_scale(tsc_khz, freq->cpu); + } return 0; } |