From: Dirk Brandewie <dirk.brandewie@gmail.com>
Date: Thu, 4 Apr 2013 17:35:35 +0000 (-0700)
Subject: cpufreq / intel_pstate: Set timer timeout correctly
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ec376a2ab97ec3be52ca282dc6ac102e805d1005;p=linux-beck.git

cpufreq / intel_pstate: Set timer timeout correctly

The current calculation of the delay time is wrong and a cut and
paste error from a previous experimental driver.  This can result in
the timeout being set to jiffies + 1 which setup the driver to race
with itself if the APIC timer interrupt happens at just the right
time.

References: https://bugzilla.redhat.com/show_bug.cgi?id=920289
Reported-by: Adam Williamson <awilliam@redhat.com>
Reported-and-tested-by: Parag Warudkar <parag.lkml@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index ad72922919ed..6133ef5cf671 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -502,7 +502,6 @@ static inline void intel_pstate_set_sample_time(struct cpudata *cpu)
 
 	sample_time = cpu->pstate_policy->sample_rate_ms;
 	delay = msecs_to_jiffies(sample_time);
-	delay -= jiffies % delay;
 	mod_timer_pinned(&cpu->timer, jiffies + delay);
 }