From: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Date: Thu, 27 Apr 2023 12:38:42 +0000 (+0000)
Subject: tools/cgcreate: add -p <pid> support for systemd scope
X-Git-Tag: v3.1.0~82
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=541609c0e4dc9b3f355ca7a62ff28132cfb8eb11;p=thirdparty%2Flibcgroup.git

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 14606b8e..ff9c3102 100644
--- 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);
 		}