powerpc-utils/powerpc-utils-threads.patch

The current logic in ppc64_cpu will loop through the maximum number
of cpu threads (set to 1024) when trying to determine or set a particular
cpu attribuite.

For example, when setting smt mode, the code would try to set cpu
thread 0..1024 either online or offline until a failure occurs.  This
usually was trying to set the smt mode for a cpu thread that does not exist.
While this is mostly harmless, the side effect was that an error was returned
even though the smt setting operation completed successfully.

This patch changes the logic so that it only tries to set cpu attributes for
the cpu threads that are present on the system.  This resolves the inadvertent
error return and is logically a bit nicer than trying all possible threads.

Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
---

 src/ppc64_cpu.c |   50 ++++++++++++++++++++++++++++----------------------
 1 file changed, 28 insertions(+), 22 deletions(-)

Index: powerpc-utils/src/ppc64_cpu.c
===================================================================
--- powerpc-utils.orig/src/ppc64_cpu.c	2009-12-01 13:31:21.000000000 -0600
+++ powerpc-utils/src/ppc64_cpu.c	2009-12-02 13:53:34.000000000 -0600
@@ -19,11 +19,12 @@
 #define SYSFS_CPUDIR	"/sys/devices/system/cpu/cpu%d"
 #define INTSERV_PATH	"/proc/device-tree/cpus/%s/ibm,ppc-interrupt-server#s"
 #define SYSFS_PATH_MAX	128
-#define MAX_THREADS	1024
 
 #define DIAGNOSTICS_RUN_MODE	42
 
-int threads_per_cpu;
+int threads_per_cpu = 0;
+int cpus_in_system = 0;
+int threads_in_system = 0;
 
 int get_attribute(char *path, int *value)
 {
@@ -72,7 +73,7 @@
 	int i, rc;
 	int system_attribute = -1;
 
-	for (i = 0; i < MAX_THREADS; i++) {
+	for (i = 0; i < threads_in_system; i++) {
 		int cpu_attribute;
 
 		/* only check online cpus */
@@ -99,7 +100,7 @@
 	char path[SYSFS_PATH_MAX];
 	int i, rc;
 
-	for (i = 0; i < MAX_THREADS; i++) {
+	for (i = 0; i < threads_in_system; i++) {
 		/* only set online cpus */
 		if (!cpu_online(i))
 			continue;
@@ -113,11 +114,11 @@
 	return 0;
 }
 
-int get_threads_per_cpu(void)
+int get_cpu_info(void)
 {
 	DIR *d;
 	struct dirent *de;
-	int nthreads = -1;
+	int first_cpu = 1;
 	int rc;
 
 	d = opendir("/proc/device-tree/cpus");
@@ -126,20 +127,25 @@
 
 	while ((de = readdir(d)) != NULL) {
 		if (!strncmp(de->d_name, "PowerPC", 7)) {
-			struct stat sbuf;
-			char path[128];
+			if (first_cpu) {
+				struct stat sbuf;
+				char path[128];
+
+				sprintf(path, INTSERV_PATH, de->d_name);
+				rc = stat(path, &sbuf);
+				if (!rc)
+					threads_per_cpu = sbuf.st_size / 4;
 
-			sprintf(path, INTSERV_PATH, de->d_name);
-			rc = stat(path, &sbuf);
-			if (!rc)
-				nthreads = sbuf.st_size / 4;
+				first_cpu = 0;
+			}
 
-			break;
+			cpus_in_system++;
 		}
 	}
 
 	closedir(d);
-	return nthreads;
+	threads_in_system = cpus_in_system * threads_per_cpu;
+	return 0;
 }
 
 int is_smt_capable(void)
@@ -148,7 +154,7 @@
 	char path[SYSFS_PATH_MAX];
 	int i;
 
-	for (i = 0; i < MAX_THREADS; i++) {
+	for (i = 0; i < threads_in_system; i++) {
 		sprintf(path, SYSFS_CPUDIR"/smt_snooze_delay", i);
 		if (stat(path, &sb))
 			continue;
@@ -187,7 +193,7 @@
 	int system_state = -1;
 	int i;
 
-	for (i = 0; i < MAX_THREADS; i += threads_per_cpu) {
+	for (i = 0; i < threads_in_system; i += threads_per_cpu) {
 		int cpu_state;
 
 		cpu_state = get_one_smt_state(i);
@@ -236,7 +242,7 @@
 	if (rc)
 		update_ssd = 0;
 
-	for (i = 0; i < MAX_THREADS; i += threads_per_cpu) {
+	for (i = 0; i < threads_in_system; i += threads_per_cpu) {
 		rc = set_one_smt_state(i, smt_state);
 		if (rc)
 			break;
@@ -254,7 +260,7 @@
 	char path[SYSFS_PATH_MAX];
 	int i;
 
-	for (i = 0; i < MAX_THREADS; i++) {
+	for (i = 0; i < threads_in_system; i++) {
 		sprintf(path, SYSFS_CPUDIR"/dscr", i);
 		if (stat(path, &sb))
 			continue;
@@ -436,10 +442,10 @@
 		return 0;
 	}
 
-	threads_per_cpu = get_threads_per_cpu();
-	if (threads_per_cpu < 0) {
-		printf("Could not determine thread count\n");
-		return -1;
+	rc = get_cpu_info();
+	if (rc) {
+		printf("Could not determine system cpu/thread information.\n");
+		return rc;
 	}
 
 	while (1) {