support use of 'all' containers when cgmanager supports it

Introduce a new list of controllers just containing "all".

Make the lists of controllers null-terminated.

If the cgmanager api version is high enough, use the 'all' controller
rather than walking all controllers, which should greatly reduce the
amount of dbus overhead.  This will be especially important for
those going through a cgproxy.

Also remove the call to cleanup cgroups when a cgroup existed.  That
usually fails (and failure is ignored) since the to-be-cleaned-up
cgroup is busy, but we shouldn't even be trying.  Note this can
create for extra un-cleanedup cgroups, however it's better than us
accidentally removing a cgroup that someone else had created and was
about to use.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

diff --git a/src/lxc/cgmanager.c b/src/lxc/cgmanager.c
index 97d19ca13e484d6ec53cc63f5f6e4acf197c7c80..a11d42f516beda1871fe909d761eceec34c00676 100644 (file)
--- a/src/lxc/cgmanager.c
+++ b/src/lxc/cgmanager.c
@@ -53,6 +53,7 @@
 
 #define CGM_SUPPORTS_GET_ABS 3
 #define CGM_SUPPORTS_NAMED 4
+#define CGM_SUPPORTS_MULT_CONTROLLERS 10
 
 #ifdef HAVE_CGMANAGER
 lxc_log_define(lxc_cgmanager, lxc);
@@ -114,7 +115,7 @@ static int32_t api_version;
 
 static struct cgroup_ops cgmanager_ops;
 static int nr_subsystems;
-static char **subsystems;
+static char **subsystems, **subsystems_inone;
 static bool dbus_threads_initialized = false;
 static void cull_user_controllers(void);
 
@@ -181,6 +182,11 @@ static bool cgm_dbus_connect(void)
        return true;
 }
 
+static inline bool cgm_supports_multiple_controllers(void)
+{
+       return api_version >= CGM_SUPPORTS_MULT_CONTROLLERS;
+}
+
 static int send_creds(int sock, int rpid, int ruid, int rgid)
 {
        struct msghdr msg = { 0 };
@@ -242,15 +248,19 @@ static bool lxc_cgmanager_escape(void)
 {
        bool ret = true;
        pid_t me = getpid();
+       char **slist = subsystems;
        int i;
 
-       for (i = 0; i < nr_subsystems; i++) {
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+
+       for (i = 0; slist[i]; i++) {
                if (cgmanager_move_pid_abs_sync(NULL, cgroup_manager,
-                                       subsystems[i], "/", me) != 0) {
+                                       slist[i], "/", me) != 0) {
                        NihError *nerr;
                        nerr = nih_error_get();
                        ERROR("call to cgmanager_move_pid_abs_sync(%s) failed: %s",
-                                       subsystems[i], nerr->message);
+                                       slist[i], nerr->message);
                        nih_free(nerr);
                        ret = false;
                        break;
@@ -340,7 +350,8 @@ out:
 static int chown_cgroup_wrapper(void *data)
 {
        struct chown_data *arg = data;
-       int i;
+       char **slist = subsystems;
+       int i, ret = -1;
        uid_t destuid;
 
        if (setresgid(0,0,0) < 0)
@@ -355,15 +366,21 @@ static int chown_cgroup_wrapper(void *data)
                return -1;
        }
        destuid = get_ns_uid(arg->origuid);
-       for (i = 0; i < nr_subsystems; i++) {
-               if (do_chown_cgroup(subsystems[i], arg->cgroup_path, destuid) < 0) {
+
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+
+       for (i = 0; slist[i]; i++) {
+               if (do_chown_cgroup(slist[i], arg->cgroup_path, destuid) < 0) {
                        ERROR("Failed to chown %s:%s to container root",
-                               subsystems[i], arg->cgroup_path);
-                       return -1;
+                               slist[i], arg->cgroup_path);
+                       goto fail;
                }
        }
+       ret = 0;
+fail:
        cgm_dbus_disconnect();
-       return 0;
+       return ret;
 }
 
 /* Internal helper.  Must be called with the cgmanager dbus socket open */
@@ -385,6 +402,7 @@ static bool lxc_cgmanager_chmod(const char *controller,
 static bool chown_cgroup(const char *cgroup_path, struct lxc_conf *conf)
 {
        struct chown_data data;
+       char **slist = subsystems;
        int i;
 
        if (lxc_list_empty(&conf->id_map))
@@ -407,12 +425,15 @@ static bool chown_cgroup(const char *cgroup_path, struct lxc_conf *conf)
         * This can't be done in the child namespace because it only group-owns
         * the cgroup
         */
-       for (i = 0; i < nr_subsystems; i++) {
-               if (!lxc_cgmanager_chmod(subsystems[i], cgroup_path, "", 0775))
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+
+       for (i = 0; slist[i]; i++) {
+               if (!lxc_cgmanager_chmod(slist[i], cgroup_path, "", 0775))
                        return false;
-               if (!lxc_cgmanager_chmod(subsystems[i], cgroup_path, "tasks", 0775))
+               if (!lxc_cgmanager_chmod(slist[i], cgroup_path, "tasks", 0775))
                        return false;
-               if (!lxc_cgmanager_chmod(subsystems[i], cgroup_path, "cgroup.procs", 0775))
+               if (!lxc_cgmanager_chmod(slist[i], cgroup_path, "cgroup.procs", 0775))
                        return false;
        }
 
@@ -478,6 +499,7 @@ err1:
 static void cgm_destroy(void *hdata)
 {
        struct cgm_data *d = hdata;
+       char **slist = subsystems;
        int i;
 
        if (!d || !d->cgroup_path)
@@ -486,8 +508,11 @@ static void cgm_destroy(void *hdata)
                ERROR("Error connecting to cgroup manager");
                return;
        }
-       for (i = 0; i < nr_subsystems; i++)
-               cgm_remove_cgroup(subsystems[i], d->cgroup_path);
+
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+       for (i = 0; slist[i]; i++)
+               cgm_remove_cgroup(slist[i], d->cgroup_path);
 
        free(d->name);
        if (d->cgroup_path)
@@ -503,13 +528,18 @@ static void cgm_destroy(void *hdata)
 static inline void cleanup_cgroups(char *path)
 {
        int i;
-       for (i = 0; i < nr_subsystems; i++)
-               cgm_remove_cgroup(subsystems[i], path);
+       char **slist = subsystems;
+
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+       for (i = 0; slist[i]; i++)
+               cgm_remove_cgroup(slist[i], path);
 }
 
 static inline bool cgm_create(void *hdata)
 {
        struct cgm_data *d = hdata;
+       char **slist = subsystems;
        int i, index=0, baselen, ret;
        int32_t existed;
        char result[MAXPATHLEN], *tmp, *cgroup_path;
@@ -545,9 +575,13 @@ again:
                        goto bad;
        }
        existed = 0;
-       for (i = 0; i < nr_subsystems; i++) {
-               if (!lxc_cgmanager_create(subsystems[i], tmp, &existed)) {
-                       ERROR("Error creating cgroup %s:%s", subsystems[i], result);
+
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+
+       for (i = 0; slist[i]; i++) {
+               if (!lxc_cgmanager_create(slist[i], tmp, &existed)) {
+                       ERROR("Error creating cgroup %s:%s", slist[i], result);
                        cleanup_cgroups(tmp);
                        goto bad;
                }
@@ -565,7 +599,6 @@ again:
        return true;
 
 next:
-       cleanup_cgroups(tmp);
        index++;
        goto again;
 bad:
@@ -606,10 +639,14 @@ static bool lxc_cgmanager_enter(pid_t pid, const char *controller,
 /* Internal helper, must be called with cgmanager dbus socket open */
 static bool do_cgm_enter(pid_t pid, const char *cgroup_path, bool abs)
 {
+       char **slist = subsystems;
        int i;
 
-       for (i = 0; i < nr_subsystems; i++) {
-               if (!lxc_cgmanager_enter(pid, subsystems[i], cgroup_path, abs))
+       if (cgm_supports_multiple_controllers())
+               slist = subsystems_inone;
+
+       for (i = 0; slist[i]; i++) {
+               if (!lxc_cgmanager_enter(pid, slist[i], cgroup_path, abs))
                        return false;
        }
        return true;
@@ -996,6 +1033,12 @@ static bool collect_subsytems(void)
        if (subsystems) // already initialized
                return true;
 
+       subsystems_inone = malloc(2 * sizeof(char *));
+       if (!subsystems_inone)
+               return false;
+       subsystems_inone[0] = "all";
+       subsystems_inone[1] = NULL;
+
        f = fopen_cloexec("/proc/self/cgroup", "r");
        if (!f) {
                f = fopen_cloexec("/proc/1/cgroup", "r");
@@ -1022,12 +1065,13 @@ static bool collect_subsytems(void)
                for (p = strtok_r(slist, ",", &saveptr);
                                p;
                                p = strtok_r(NULL, ",", &saveptr)) {
-                       tmp = realloc(subsystems, (nr_subsystems+1)*sizeof(char *));
+                       tmp = realloc(subsystems, (nr_subsystems+2)*sizeof(char *));
                        if (!tmp)
                                goto out_free;
 
                        subsystems = tmp;
                        tmp[nr_subsystems] = strdup(p);
+                       tmp[nr_subsystems+1] = NULL;
                        if (!tmp[nr_subsystems])
                                goto out_free;
                        nr_subsystems++;