[LTP] [PATCH v4 1/7] lib/mem: modified _gather_cpus() as _gather_node_cpus()

[Zhouping L. <zl...@re...>]

The previous _gather_cpus() tried to collect all the specified
node's cpus, but it didn't pay attention to the offline cpus,
if one cpu in the specified node were offline, it can't write
the cpu number to cgroups/*.cpus, and return -EINVAL.

The patch fixed it, and modified the function name, as the new
name make more sense.

Signed-off-by: Zhouping Liu <zl...@re...>
---
 testcases/kernel/mem/lib/mem.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/testcases/kernel/mem/lib/mem.c b/testcases/kernel/mem/lib/mem.c
index a827b25..72ac06d 100644
--- a/testcases/kernel/mem/lib/mem.c
+++ b/testcases/kernel/mem/lib/mem.c
@@ -20,6 +20,7 @@
 #include "test.h"
 #include "usctest.h"
 #include "safe_macros.h"
+#include "safe_file_ops.h"
 #include "_private.h"
 #include "mem.h"
 #include "numa_helper.h"
@@ -481,20 +482,37 @@ void ksm_usage(void)
 
 /* cpuset/memcg */
 
-static void _gather_cpus(char *cpus, long nd)
+static void _gather_node_cpus(char *cpus, long nd)
 {
 	int ncpus = 0;
 	int i;
+	long online;
 	char buf[BUFSIZ];
+	char path[BUFSIZ], path1[BUFSIZ];
 
 	while (path_exist(PATH_SYS_SYSTEM "/cpu/cpu%d", ncpus))
 		ncpus++;
 
-	for (i = 0; i < ncpus; i++)
-		if (path_exist(PATH_SYS_SYSTEM "/node/node%ld/cpu%d", nd, i)) {
+	for (i = 0; i < ncpus; i++) {
+		snprintf(path, BUFSIZ,
+			 PATH_SYS_SYSTEM "/node/node%ld/cpu%d", nd, i);
+		if (path_exist(path, nd, i)) {
+			snprintf(path1, BUFSIZ, "%s/online", path);
+			/*
+			 * No cpu0/online knob, as it can't support to
+			 * on/offline cpu0, so if the 'nd' node contains
+			 * cpu0, it should skip to check cpu0/online's value.
+			 */
+			if (i == 0)
+				goto next;
+			SAFE_FILE_SCANF(cleanup, path1, "%ld", &online);
+			if (online == 0)
+				continue;
+next:
 			sprintf(buf, "%d,", i);
 			strcat(cpus, buf);
 		}
+	}
 	/* Remove the trailing comma. */
 	cpus[strlen(cpus) - 1] = '\0';
 }
@@ -563,7 +581,7 @@ void write_cpusets(long nd)
 	snprintf(buf, BUFSIZ, "%ld", nd);
 	write_cpuset_files(CPATH_NEW, "mems", buf);
 
-	_gather_cpus(cpus, nd);
+	_gather_node_cpus(cpus, nd);
 	write_cpuset_files(CPATH_NEW, "cpus", cpus);
 
 	snprintf(buf, BUFSIZ, "%d", getpid());
-- 
1.7.11.7