Commit 9f7ff893 authored Apr 23, 2014 by Stephane Eranian Committed by Ingo Molnar Apr 24, 2014

perf/x86: Fix RAPL rdmsrl_safe() usage



This patch fixes a bug introduced by:

  24223657 ("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>

parent 89b90ee3

arch/x86/kernel/cpu/perf_event_intel_rapl.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -543,7 +543,8 @@ static int rapl_cpu_prepare(int cpu)
		if (phys_id < 0)
		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;

		pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu));