linux-kernel - [PATCH v2] cpupower : Fix cpupower working when cpu0 is offline

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Date:   Tue,  7 Nov 2017 12:50:05 +0530
From:   Abhishek Goel <huntbag@...ux.vnet.ibm.com>
To:     trenn@...e.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Abhishek Goel <huntbag@...ux.vnet.ibm.com>
Subject: [PATCH v2] cpupower : Fix cpupower working when cpu0 is offline

cpuidle_monitor used to assume that cpu0 is always online which is not
a valid assumption on POWER machines. This patch fixes this by searching
for the first online cpu and uses it, instead of always using cpu0 for
monitoring which may not be online.

Signed-off-by: Abhishek Goel <huntbag@...ux.vnet.ibm.com>
---
v2: Commit message updated.
---
 tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c b/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
index 1b5da00..adacf99 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
+++ b/tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c
@@ -130,15 +130,23 @@ static struct cpuidle_monitor *cpuidle_register(void)
 {
 	int num;
 	char *tmp;
+	int first_online_cpu;
+
+	for (num = 0; num < cpu_count; num++) {
+		if (cpupower_is_cpu_online(num))
+			break;
+	};
+	first_online_cpu = num;
 
 	/* 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(first_online_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(first_online_cpu, num);
 		if (tmp == NULL)
 			continue;
 
@@ -146,7 +154,7 @@ static struct cpuidle_monitor *cpuidle_register(void)
 		strncpy(cpuidle_cstates[num].name, tmp, CSTATE_NAME_LEN - 1);
 		free(tmp);
 
-		tmp = cpuidle_state_desc(0, num);
+		tmp = cpuidle_state_desc(first_online_cpu, num);
 		if (tmp == NULL)
 			continue;
 		strncpy(cpuidle_cstates[num].desc, tmp,	CSTATE_DESC_LEN - 1);
-- 
2.9.3