linux-kernel - [PATCH 4.14 035/156] cpupower : Fix cpupower working when cpu0 is offline

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Date:   Fri,  2 Feb 2018 17:56:56 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Abhishek Goel <huntbag@...ux.vnet.ibm.com>,
        Shuah Khan <shuahkh@....samsung.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.14 035/156] cpupower : Fix cpupower working when cpu0 is offline

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Abhishek Goel <huntbag@...ux.vnet.ibm.com>


[ Upstream commit dbdc468f35ee827cab2753caa1c660bdb832243a ]

cpuidle_monitor used to assume that cpu0 is always online which is not
a valid assumption on POWER machines. This patch fixes this by getting
the cpu on which the current thread is running, instead of always using
cpu0 for monitoring which may not be online.

Signed-off-by: Abhishek Goel <huntbag@...ux.vnet.ibm.com>
Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
+++ b/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
@@ -130,15 +130,18 @@ static struct cpuidle_monitor *cpuidle_r
 {
 	int num;
 	char *tmp;
+	int this_cpu;
+
+	this_cpu = sched_getcpu();
 
 	/* Assume idle state count is the same for all CPUs */
-	cpuidle_sysfs_monitor.hw_states_num = cpuidle_state_count(0);
+	cpuidle_sysfs_monitor.hw_states_num = cpuidle_state_count(this_cpu);
 
 	if (cpuidle_sysfs_monitor.hw_states_num <= 0)
 		return NULL;
 
 	for (num = 0; num < cpuidle_sysfs_monitor.hw_states_num; num++) {
-		tmp = cpuidle_state_name(0, num);
+		tmp = cpuidle_state_name(this_cpu, num);
 		if (tmp == NULL)
 			continue;
 
@@ -146,7 +149,7 @@ static struct cpuidle_monitor *cpuidle_r
 		strncpy(cpuidle_cstates[num].name, tmp, CSTATE_NAME_LEN - 1);
 		free(tmp);
 
-		tmp = cpuidle_state_desc(0, num);
+		tmp = cpuidle_state_desc(this_cpu, num);
 		if (tmp == NULL)
 			continue;
 		strncpy(cpuidle_cstates[num].desc, tmp,	CSTATE_DESC_LEN - 1);