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perf/x86: Fix RAPL rdmsrl_safe() usage 

This patch fixes a bug introduced by:

  2422365780 ("perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU")

The rdmsrl_safe() function returns 0 on success.
The current code was failing to detect the RAPL PMU
on real hardware  (missing /sys/devices/power) because
the return value of rdmsrl_safe() was misinterpreted.

Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Venkatesh Srinivas <venkateshs@google.com>
Cc: peterz@infradead.org
Cc: zheng.z.yan@intel.com
Link: http://lkml.kernel.org/r/20140423170418.GA12767@quad
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Stephane Eranian 2014-04-23 19:04:19 +02:00 committed by Ingo Molnar
parent 89b90ee37a
commit 9f7ff8931e
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kernel/cpu/perf_event_intel_rapl.c
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@ -543,7 +543,8 @@ static int rapl_cpu_prepare(int cpu)
if (phys_id < 0) if (phys_id < 0)
return -1; return -1;
if (!rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits)) /* protect rdmsrl() to handle virtualization */
if (rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits))
return -1; return -1;
pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu)); pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu));