tools/cgget: add '-c' option

Add '-c' option to cgget, that prints the controllers and their
versions,
this is useful for the user, who wants to list the available controllers
and/or their version too.

 $ cgget -c
 #Controller     Version
 cpu             2
 memory          2
 cpuset          1
 misc            1
 hugetlb         1
 blkio           1
 net_cls         1
 net_prio        1
 freezer         1
 devices         1
 pids            1
 perf_event      1
 rdma            1

this option works with legacy, unified, and hybrid cgroup setup modes.

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
TJH: Changed comment formatting
(cherry picked from commit fd173c8201a11a77103f166b61f1bf33187195d0)

diff --git a/src/tools/cgget.c b/src/tools/cgget.c
index 4447ecfe551c21a3ace7c8149e12178e5cbf4bc2..26a872e809fd4b8f1e6d97489e082dcd9c6ee0ed 100644 (file)
--- a/src/tools/cgget.c
+++ b/src/tools/cgget.c
@@ -20,6 +20,7 @@
 #define LL_MAX                 100
 
 static int find_cgroup_mount_type(void);
+static int print_controller_version(void);
 
 static const struct option long_options[] = {
        {"variable",    required_argument, NULL, 'r'},
@@ -49,6 +50,7 @@ static void usage(int status, const char *program_name)
 #ifdef WITH_SYSTEMD
        info("  -b                              Ignore default systemd delegate hierarchy\n");
 #endif
+       info("  -c                              Display controller version\n");
 }
 
 static int get_controller_from_name(const char * const name, char **controller)
@@ -400,18 +402,19 @@ static int parse_opts(int argc, char *argv[], struct cgroup **cg_list[], int * c
        bool first_cgroup_is_dummy = false;
        bool cgroup_mount_type = false;
        bool fill_controller = false;
+       bool print_ctrl_ver = false;
        int ret = 0;
        int c;
 
        /* Parse arguments. */
 #ifdef WITH_SYSTEMD
-       while ((c = getopt_long(argc, argv, "r:hnvg:amb", long_options, NULL)) > 0) {
+       while ((c = getopt_long(argc, argv, "r:hnvg:ambc", long_options, NULL)) > 0) {
                switch (c) {
                case 'b':
                        *mode = (*mode) & (INT_MAX ^ MODE_SYSTEMD_DELEGATE);
                        break;
 #else
-       while ((c = getopt_long(argc, argv, "r:hnvg:am", long_options, NULL)) > 0) {
+       while ((c = getopt_long(argc, argv, "r:hnvg:amc", long_options, NULL)) > 0) {
                switch (c) {
 #endif
                case 'h':
@@ -454,6 +457,9 @@ static int parse_opts(int argc, char *argv[], struct cgroup **cg_list[], int * c
                case 'm':
                        cgroup_mount_type = true;
                        break;
+               case 'c':
+                       print_ctrl_ver = true;
+                       break;
                default:
                        usage(1, argv[0]);
                        exit(EXIT_BADARGS);
@@ -466,8 +472,9 @@ static int parse_opts(int argc, char *argv[], struct cgroup **cg_list[], int * c
                exit(EXIT_BADARGS);
        }
 
-       /* '-m' should not used with other options */
-       if (cgroup_mount_type && (fill_controller || do_not_fill_controller)) {
+       /* '-m' and '-c' should not used with other options */
+       if ((cgroup_mount_type || print_ctrl_ver) &&
+           (fill_controller || do_not_fill_controller)) {
                usage(1, argv[0]);
                exit(EXIT_BADARGS);
        }
@@ -478,6 +485,12 @@ static int parse_opts(int argc, char *argv[], struct cgroup **cg_list[], int * c
                        goto err;
        }
 
+       if (print_ctrl_ver) {
+               ret = print_controller_version();
+               if (ret)
+                       goto err;
+       }
+
        ret = parse_opt_args(argc, argv, cg_list, cg_list_len, first_cgroup_is_dummy);
        if (ret)
                goto err;
@@ -843,3 +856,27 @@ static int find_cgroup_mount_type(void)
 
        return ret;
 }
+
+static int print_controller_version(void)
+{
+       struct cgroup_mount_point controller;
+       enum cg_version_t version;
+       void *handle;
+       int ret = 0;
+
+       /* perf_event controller is the one with the lengthiest name */
+       info("%-11s\t%-7s\n", "#Controller","Version");
+       ret = cgroup_get_controller_begin(&handle, &controller);
+       while (ret == 0) {
+               ret = cgroup_get_controller_version(controller.name, &version);
+               if (!ret)
+                       info("%-11s\t%d\n", controller.name, version);
+               else
+                       info("%-11s\t%-7s\n", controller.name, "unknown");
+
+               ret = cgroup_get_controller_next(&handle, &controller);
+       }
+       cgroup_get_controller_end(&handle);
+
+       return ret;
+}