From 0d0c87a57f701a30ce5ecafdbfb7169c62412793 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Sat, 14 Apr 2012 02:34:10 +0200
Subject: [PATCH] manager: remove unavailable/redundant entries from default
 controllers list (cherry picked from commit
 9156e799a258658cf3f51434708cdb194c13eaa4)

---
 src/core/cgroup.c  |   41 ++++++++++++++++++++++++++++++++++++++---
 src/core/cgroup.h  |    1 +
 src/core/manager.c |    5 ++++-
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 6ae9f48..0ea6395 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -30,6 +30,7 @@
 #include "cgroup.h"
 #include "cgroup-util.h"
 #include "log.h"
+#include "strv.h"
 
 int cgroup_bonding_realize(CGroupBonding *b) {
         int r;
@@ -305,7 +306,8 @@ int manager_setup_cgroup(Manager *m) {
         }
 
         /* 1. Determine hierarchy */
-        if ((r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &current)) < 0) {
+        r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &current);
+        if (r < 0) {
                 log_error("Cannot determine cgroup we are running in: %s", strerror(-r));
                 goto finish;
         }
@@ -352,7 +354,8 @@ int manager_setup_cgroup(Manager *m) {
                 log_debug("Release agent already installed.");
 
         /* 4. Realize the group */
-        if ((r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, 0)) < 0) {
+        r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, 0);
+        if (r < 0) {
                 log_error("Failed to create root cgroup hierarchy: %s", strerror(-r));
                 goto finish;
         }
@@ -361,7 +364,8 @@ int manager_setup_cgroup(Manager *m) {
         if (m->pin_cgroupfs_fd >= 0)
                 close_nointr_nofail(m->pin_cgroupfs_fd);
 
-        if ((m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK)) < 0) {
+        m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK);
+        if (r < 0) {
                 log_error("Failed to open pin file: %m");
                 r = -errno;
                 goto finish;
@@ -369,6 +373,8 @@ int manager_setup_cgroup(Manager *m) {
 
         log_debug("Created root group.");
 
+        manager_shorten_default_controllers(m);
+
 finish:
         free(current);
         free(path);
@@ -391,6 +397,35 @@ void manager_shutdown_cgroup(Manager *m, bool delete) {
         m->cgroup_hierarchy = NULL;
 }
 
+void manager_shorten_default_controllers(Manager *m) {
+        char **f, **t;
+
+        strv_uniq(m->default_controllers);
+
+        if (!m->default_controllers)
+                return;
+
+        for (f = m->default_controllers, t = m->default_controllers; *f; f++) {
+
+                if (!streq(*f, "systemd") && !streq(*f, "name=systemd")) {
+                        char *cc;
+
+                        cc = alloca(sizeof("/sys/fs/cgroup/") + strlen(*f));
+                        strcpy(stpcpy(cc, "/sys/fs/cgroup/"), *f);
+
+                        if (access(cc, F_OK) >= 0) {
+                                *(t++) = *f;
+                                continue;
+                        }
+                }
+
+                log_debug("Controller %s not available or redundant, removing from default controllers list.", *f);
+                free(*f);
+        }
+
+        *t = NULL;
+}
+
 int cgroup_bonding_get(Manager *m, const char *cgroup, CGroupBonding **bonding) {
         CGroupBonding *b;
         char *p;
diff --git a/src/core/cgroup.h b/src/core/cgroup.h
index 35ae52b..17ae14f 100644
--- a/src/core/cgroup.h
+++ b/src/core/cgroup.h
@@ -85,6 +85,7 @@ pid_t cgroup_bonding_search_main_pid_list(CGroupBonding *b);
 
 int manager_setup_cgroup(Manager *m);
 void manager_shutdown_cgroup(Manager *m, bool delete);
+void manager_shorten_default_controllers(Manager *m);
 
 int cgroup_bonding_get(Manager *m, const char *cgroup, CGroupBonding **bonding);
 int cgroup_notify_empty(Manager *m, const char *group);
diff --git a/src/core/manager.c b/src/core/manager.c
index d57e8c1..97be7ce 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -3165,12 +3165,15 @@ int manager_set_default_controllers(Manager *m, char **controllers) {
 
         assert(m);
 
-        if (!(l = strv_copy(controllers)))
+        l = strv_copy(controllers);
+        if (!l)
                 return -ENOMEM;
 
         strv_free(m->default_controllers);
         m->default_controllers = l;
 
+        manager_shorten_default_controllers(m);
+
         return 0;
 }