cpupower: Fix checks for CPU existence

Commit Message

Ben Hutchings April 18, 2017, 2:31 a.m. UTC

Calls to cpufreq_cpu_exists(cpu) were converted to
cpupower_is_cpu_online(cpu) when libcpupower was introduced and the
former function was deleted.  However, cpupower_is_cpu_online()
returns 1 on success whereas cpufreq_cpu_exists() returned 0 on
success.  It also does not distinguish physically absent and offline
CPUs, and does not set errno.

cpufreq-set has already been fixed (commit c25badc9ceb6).

In cpufreq-bench, which prints an error message for offline CPUs,
properly distinguish and report the zero and negative cases.

Fixes: ac5a181d065d ("cpupower: Add cpuidle parts into library")
Signed-off-by: Ben Hutchings <[e-mail]>
---

Patch

--- a/tools/power/cpupower/bench/system.c
+++ b/tools/power/cpupower/bench/system.c
@@ -58,12 +58,19 @@  long long int get_time()
 
 int set_cpufreq_governor(char *governor, unsigned int cpu)
 {
+	int rc;
 
 	dprintf("set %s as cpufreq governor\n", governor);
 
-	if (cpupower_is_cpu_online(cpu) != 0) {
-		perror("cpufreq_cpu_exists");
-		fprintf(stderr, "error: cpu %u does not exist\n", cpu);
+	rc = cpupower_is_cpu_online(cpu);
+	if (rc != 1) {
+		if (rc < 0)
+			fprintf(stderr, "cpupower_is_cpu_online: %s\n",
+				strerror(-rc));
+		else
+			fprintf(stderr,
+				"error: cpu %u is offline or does not exist\n",
+				cpu);
 		return -1;
 	}