tools/cgcreate: add -p <pid> support for systemd scope

Currently, an idle_thread is created for the transient systemd scope by
default, it works fine, when the slice/scope creation is treated in par
to create of traditional cgroup, but the user may wish to create a
slice/scope, with a process of their choice, instead of a default idle
thread.  Add support to pass task pid via '-p/--pid' option, while
creating a systemd slice/scope.

 # ./src/tools/cgcreate -c -gcpu:foo.slice/bar.scope --pid=4253

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>

diff --git a/src/tools/cgcreate.c b/src/tools/cgcreate.c
index 14606b8e733a3ae95965ba30ab283a4d870e025a..ff9c3102f9a6ff27128a1a211b0bb866f93283e4 100644 (file)
--- a/src/tools/cgcreate.c
+++ b/src/tools/cgcreate.c
@@ -45,6 +45,8 @@ static void usage(int status, const char *program_name)
        info("  -b                              Ignore default systemd");
        info("delegate hierarchy\n");
        info("  -c, --scope                     Create a delegated systemd scope\n");
+       info("  -p, --pid=pid                   Task pid to use to create systemd ");
+       info("scope\n");
        info("  -S, --setdefault                Set this scope as the default scope ");
        info("delegate hierarchy\n");
 #endif
@@ -52,7 +54,7 @@ static void usage(int status, const char *program_name)
 
 #ifdef WITH_SYSTEMD
 static int create_systemd_scope(struct cgroup * const cg, const char * const prog_name,
-                               int set_default)
+                               int set_default, pid_t pid)
 {
        struct cgroup_systemd_scope_opts opts;
        char slice[FILENAME_MAX];
@@ -64,6 +66,8 @@ static int create_systemd_scope(struct cgroup * const cg, const char * const pro
        if (ret)
                return ret;
 
+       opts.pid = pid;
+
        ret = cgroup_create_scope2(cg, 0, &opts);
        if (!ret && set_default) {
                scope = strstr(cg->name, "/");
@@ -115,6 +119,7 @@ int main(int argc, char *argv[])
 #ifdef WITH_SYSTEMD
                {"scope",             no_argument, NULL, 'c'},
                {"setdefault",        no_argument, NULL, 'S'},
+               {"pid",         required_argument, NULL, 'p'},
 #endif /* WITH_SYSTEMD */
                {0, 0, 0, 0},
        };
@@ -123,8 +128,9 @@ int main(int argc, char *argv[])
        gid_t tgid = CGRULE_INVALID, agid = CGRULE_INVALID;
 
        int ignore_default_systemd_delegate_slice = 0;
-       int create_scope = 0;
        int set_default_scope = 0;
+       int create_scope = 0;
+       pid_t scope_pid = -1;
 
        struct cgroup_group_spec **cgroup_list;
        struct cgroup_controller *cgc;
@@ -159,7 +165,7 @@ int main(int argc, char *argv[])
 
 #ifdef WITH_SYSTEMD
        /* parse arguments */
-       while ((c = getopt_long(argc, argv, "a:t:g:hd:f:s:bcS", long_opts, NULL)) > 0) {
+       while ((c = getopt_long(argc, argv, "a:t:g:hd:f:s:bcp:S", long_opts, NULL)) > 0) {
                switch (c) {
                case 'b':
                        ignore_default_systemd_delegate_slice = 1;
@@ -167,6 +173,14 @@ int main(int argc, char *argv[])
                case 'c':
                        create_scope = 1;
                        break;
+               case 'p':
+                       scope_pid = atoi(optarg);
+                       if (scope_pid <= 1) {
+                               err("%s: Invalid pid %s\n", argv[0], optarg);
+                               ret = EXIT_BADARGS;
+                               goto err;
+                       }
+                       break;
                case 'S':
                        set_default_scope = 1;
                        break;
@@ -234,6 +248,12 @@ int main(int argc, char *argv[])
                ret = EXIT_BADARGS;
                goto err;
        }
+
+       if (!create_scope && scope_pid != -1) {
+               err("%s: \"-p\" requires \"-c\" to be provided\n", argv[0]);
+               ret = EXIT_BADARGS;
+               goto err;
+       }
 #endif
 
        /* no cgroup name */
@@ -303,7 +323,7 @@ int main(int argc, char *argv[])
                        cgroup_set_permissions(cgroup, dir_mode, file_mode, tasks_mode);
 
                if (create_scope) {
-                       ret = create_systemd_scope(cgroup, argv[0], set_default_scope);
+                       ret = create_systemd_scope(cgroup, argv[0], set_default_scope, scope_pid);
                } else {
                        ret = cgroup_create_cgroup(cgroup, 0);
                }