Properly fix sysfs_get_idlestate_count()

My previous commit 16b7c275c055 ("tools: cpupower: fix return checks for sysfs_get_idlestate_count()") was not correct. After looking
at the changelog for cpupower I noticed that Thomas had changed the return of sysfs_get_idlestate_count() to an unsigned int to simplify the code. The problem is really that both he (in his original change) and I (in my new change) missed the obvious that sysfs_get_idlestate_count()
can't return -ENODEV. It should just return 0 for "no c-states".

Patch 1 reverts my recent change and patch 2 fixes the problem correctly.

Sorry 'bout that Thomas. I should have caught that the the first time.

Prarit Bhargava (2):
Revert "tools: cpupower: fix return checks for
sysfs_get_idlestate_count()"
Fix no idle state information return value

 tools/power/cpupower/utils/cpuidle-info.c  |    8 ++++----
 tools/power/cpupower/utils/helpers/sysfs.c |    2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

1.7.9.3

This reverts commit 16b7c275c055cc36218404b5d147be7f76575087.

My previous commit 16b7c275c055 ("tools: cpupower: fix return checks for sysfs_get_idlestate_count()") was not correct. After looking
at the changelog for cpupower I noticed that Thomas had changed the return of sysfs_get_idlestate_count() to an unsigned int to simplify the code. The problem is really that both he (in his original change) and I (in my new change) missed the obvious that sysfs_get_idlestate_count()
can't return -ENODEV. It should just return 0 for "no c-states".

---
 tools/power/cpupower/utils/cpuidle-info.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

index 458d69b..75e66de 100644
@@ -22,13 +22,13 @@
 
 static void cpuidle_cpu_output(unsigned int cpu, int verbose)
 {
-	int idlestates, idlestate;
+	unsigned int idlestates, idlestate;
 	char *tmp;
 
 	printf(_ ("Analyzing CPU %d:\n"), cpu);
 
 	idlestates = sysfs_get_idlestate_count(cpu);
-	if (idlestates < 1) {
+	if (idlestates == 0) {
 		printf(_("CPU %u: No idle states\n"), cpu);
 		return;
 	}

@@ -100,10 +100,10 @@ static void cpuidle_general_output(void)
 static void proc_cpuidle_cpu_output(unsigned int cpu)
 {
 	long max_allowed_cstate = 2000000000;
-	int cstate, cstates;
+	unsigned int cstate, cstates;
 
 	cstates = sysfs_get_idlestate_count(cpu);
-	if (cstates < 1) {
+	if (cstates == 0) {
 		printf(_("CPU %u: No C-states info\n"), cpu);
 		return;
 	}

1.7.9.3

sysfs_get_idlestate_count() returns an unsigned int. Returning -ENODEV is not the right thing to do here, and in any case is handled the same way as if there are no states found.

---
 tools/power/cpupower/utils/helpers/sysfs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 09afe5d..4e8fe2c 100644
@@ -361,7 +361,7 @@ unsigned int sysfs_get_idlestate_count(unsigned int cpu)
 
 	snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
 	if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
-		return -ENODEV;
+		return 0;
 
 	snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0", cpu);
 	if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))

1.7.9.3

Yep, returning zero states instead of an error code makes a lot sense here.

Thanks!

Thomas

I'll queue up the revert, but I need an ACK from Thomas for the second patch.

I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.