cpupower: Fix checks for CPU existence

Forwarded: https://marc.info/?l=linux-pm&m=149248268214265

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() 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")
Fixes: 53d1cd6b125f ("cpupowerutils: bench - Fix cpu online check")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[carnil: Update/Refresh patch for 4.14.17: The issue with the
incorrect check has been fixed with upstream commit 53d1cd6b125f.
Keep in the patch the distinction and report for the zero and
negative cases.]

Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name cpupower-fix-checks-for-cpu-existence.patch

diff --git a/tools/power/cpupower/bench/system.c b/tools/power/cpupower/bench/system.c
index 40f3679e70b54f3558a9024bcad5aec6bdb68df4..750ae90c264e5c4dc0976d228acd97504d614609 100644 (file)
--- a/tools/power/cpupower/bench/system.c
+++ b/tools/power/cpupower/bench/system.c
@@ -45,12 +45,19 @@ 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) != 1) {
-               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;
        }