lxc-cgroup: use correct terminology

lxc-cgroup gets or sets the value of a state object (such as
'cpuset.cpus'), not the value of a subsystem (which would be
just 'cpuset').

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

diff --git a/doc/lxc-cgroup.sgml.in b/doc/lxc-cgroup.sgml.in
index 5acd313d4bc97a520cb577f7c4b900d350e753a2..80621487725a615ec2915f3dca19bb5a4cded514 100644 (file)
--- a/doc/lxc-cgroup.sgml.in
+++ b/doc/lxc-cgroup.sgml.in
@@ -48,8 +48,8 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
   <refsynopsisdiv>
     <cmdsynopsis>
-      <command>lxc-start <replaceable>-n name</replaceable>
-       <replaceable>subsystem</replaceable> <optional>value</optional>
+      <command>lxc-cgroup -n <replaceable>name</replaceable>
+       <replaceable>state-object</replaceable> <optional>value</optional>
       </command>
     </cmdsynopsis>
   </refsynopsisdiv>
@@ -58,17 +58,20 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     <title>Description</title>
 
     <para>
-      <command>lxc-cgroup</command> get or set value from the control
-      group associated with the
-      container <replaceable>name</replaceable>. If
-      no <optional>value</optional> is specified, the value of
-      the <replaceable>subsystem</replaceable> is displayed, otherwise
-      it is set. The <command>lxc-cgroup</command> does not assume the
-      correctness of the <replaceable>subsystem</replaceable> name, it
-      is up to the user to specify the
-      right <replaceable>subsystem</replaceable> name.
+      <command>lxc-cgroup</command> gets or sets the value of a
+      <replaceable>state-object</replaceable> (e.g., 'cpuset.cpus')
+      in the container's cgroup for the corresponding subsystem (e.g.,
+      'cpuset'). If no <optional>value</optional> is specified, the
+      current value of the <replaceable>state-object</replaceable> is
+      displayed; otherwise it is set.
     </para>
 
+    <para>
+      Note that <command>lxc-cgroup</command> does not check that the
+      <replaceable>state-object</replaceable> is valid for the running
+      kernel, or that the corresponding subsystem is contained in any
+      mounted cgroup hierarchy.
+    </para>
   </refsect1>
 
   <refsect1>
@@ -77,11 +80,11 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
       <varlistentry>
        <term>
-         <option><replaceable>subsystem</replaceable></option>
+         <option><replaceable>state-object</replaceable></option>
        </term>
        <listitem>
          <para>
-           Specify the subsystem control group name.
+           Specify the state object name.
          </para>
        </listitem>
       </varlistentry>
@@ -92,7 +95,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
        </term>
        <listitem>
          <para>
-           Specify the subsystem control group value to be set.
+           Specify the value to assign to the state object.
          </para>
        </listitem>
       </varlistentry>

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index e5145f9051ad69541513f7fe8a9d59e66547530d..f50c74aec73bac232515486acd4c8d3ba53bab1c 100644 (file)
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -531,8 +531,8 @@ int lxc_cgroup_path_get(char **path, const char *subsystem, const char *name)
        static char        buf[MAXPATHLEN];
        static char        retbuf[MAXPATHLEN];
 
-       /* what lxc_cgroup_set calls subsystem is actually the filename, i.e.
-          'devices.allow'.  So for our purposee we trim it */
+       /* lxc_cgroup_set passes a state object for the subsystem,
+        * so trim it to just the subsystem part */
        if (subsystem) {
                snprintf(retbuf, MAXPATHLEN, "%s", subsystem);
                char *s = index(retbuf, '.');

diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c
index d5aa5aa9a7f909f833e64ee2c8407dc85696966b..97769a5a266cce95559db69f018dbf5eba138822 100644 (file)
--- a/src/lxc/lxc_cgroup.c
+++ b/src/lxc/lxc_cgroup.c
@@ -36,7 +36,7 @@ lxc_log_define(lxc_cgroup_ui, lxc_cgroup);
 static int my_checker(const struct lxc_arguments* args)
 {
        if (!args->argc) {
-               lxc_error(args, "missing cgroup subsystem");
+               lxc_error(args, "missing state object");
                return -1;
        }
        return 0;
@@ -49,13 +49,13 @@ static const struct option my_longopts[] = {
 static struct lxc_arguments my_args = {
        .progname = "lxc-cgroup",
        .help     = "\
---name=NAME subsystem [value]\n\
+--name=NAME state-object [value]\n\
 \n\
-lxc-cgroup get or set subsystem value of cgroup\n\
-associated with the NAME container\n\
+Get or set the value of a state object (for example, 'cpuset.cpus')\n\
+in the container's cgroup for the corresponding subsystem.\n\
 \n\
 Options :\n\
-  -n, --name=NAME      NAME for name of the container",
+  -n, --name=NAME      container name",
        .options  = my_longopts,
        .parser   = NULL,
        .checker  = my_checker,
@@ -63,7 +63,7 @@ Options :\n\
 
 int main(int argc, char *argv[])
 {
-       char *subsystem = NULL, *value = NULL;
+       char *state_object = NULL, *value = NULL;
 
        if (lxc_arguments_parse(&my_args, argc, argv))
                return -1;
@@ -72,15 +72,15 @@ int main(int argc, char *argv[])
                         my_args.progname, my_args.quiet))
                return -1;
 
-       subsystem = my_args.argv[0];
+       state_object = my_args.argv[0];
 
        if ((argc) > 1)
                value = my_args.argv[1];
 
        if (value) {
-               if (lxc_cgroup_set(my_args.name, subsystem, value)) {
+               if (lxc_cgroup_set(my_args.name, state_object, value)) {
                        ERROR("failed to assign '%s' value to '%s' for '%s'",
-                               value, subsystem, my_args.name);
+                               value, state_object, my_args.name);
                        return -1;
                }
        } else {
@@ -88,10 +88,10 @@ int main(int argc, char *argv[])
                int ret;
                char buffer[len];
 
-               ret = lxc_cgroup_get(my_args.name, subsystem, buffer, len);
+               ret = lxc_cgroup_get(my_args.name, state_object, buffer, len);
                if (ret < 0) {
                        ERROR("failed to retrieve value of '%s' for '%s'",
-                             subsystem, my_args.name);
+                             state_object, my_args.name);
                        return -1;
                }