Merged revisions 275773 via svnmerge from
authorJeff Peeler <jpeeler@digium.com>
Tue, 13 Jul 2010 17:37:40 +0000 (17:37 +0000)
committerJeff Peeler <jpeeler@digium.com>
Tue, 13 Jul 2010 17:37:40 +0000 (17:37 +0000)
https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r275773 | jpeeler | 2010-07-12 15:34:51 -0500 (Mon, 12 Jul 2010) | 12 lines

  Make user removals and traversals thread safe in meetme.

  Race conditions present in meetme involving the user list where a lack of
  locking has the potential for a user to be removed during a traversal or as in
  the case of the reporter after checking if the list is empty could cause a
  crash. Fixing this was done by convering the userlist to an ao2 container.

  (closes issue #17390)
  Reported by: Vince

  Review: https://reviewboard.asterisk.org/r/746/
........

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@276074 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_meetme.c

index a812870..b0b26ae 100644 (file)
@@ -724,7 +724,7 @@ struct ast_conference {
        struct ast_frame *transframe[32];
        struct ast_frame *origframe;
        struct ast_trans_pvt *transpath[32];
-       AST_LIST_HEAD_NOLOCK(, ast_conf_user) userlist;
+       struct ao2_container *usercontainer;
        AST_LIST_ENTRY(ast_conference) list;
        /* announce_thread related data */
        pthread_t announcethread;
@@ -1133,6 +1133,30 @@ static void conf_play(struct ast_channel *chan, struct ast_conference *conf, enu
                ast_autoservice_stop(chan);
 }
 
+static int user_no_cmp(void *obj, void *arg, int flags)
+{
+       struct ast_conf_user *user = obj;
+       int *user_no = arg;
+
+       if (user->user_no == *user_no) {
+               return (CMP_MATCH | CMP_STOP);
+       }
+
+       return 0;
+}
+
+static int user_max_cmp(void *obj, void *arg, int flags)
+{
+       struct ast_conf_user *user = obj;
+       int *max_no = arg;
+
+       if (user->user_no > *max_no) {
+               *max_no = user->user_no;
+       }
+
+       return 0;
+}
+
 /*!
  * \brief Find or create a conference
  *
@@ -1166,8 +1190,10 @@ static struct ast_conference *build_conf(const char *confno, const char *pin,
                goto cnfout;
 
        /* Make a new one */
-       if (!(cnf = ast_calloc(1, sizeof(*cnf))))
+       if (!(cnf = ast_calloc(1, sizeof(*cnf))) ||
+               !(cnf->usercontainer = ao2_container_alloc(1, NULL, user_no_cmp))) {
                goto cnfout;
+       }
 
        ast_mutex_init(&cnf->playlock);
        ast_mutex_init(&cnf->listenlock);
@@ -1292,15 +1318,21 @@ static char *complete_meetmecmd(const char *line, const char *word, int pos, int
                        }
 
                        if (cnf) {
-                               /* Search for the user */
-                               AST_LIST_TRAVERSE(&cnf->userlist, usr, list) {
+                               struct ao2_iterator user_iter;
+                               user_iter = ao2_iterator_init(cnf->usercontainer, 0);
+
+                               while((usr = ao2_iterator_next(&user_iter))) {
                                        snprintf(usrno, sizeof(usrno), "%d", usr->user_no);
-                                       if (!strncasecmp(word, usrno, len) && ++which > state)
+                                       if (!strncasecmp(word, usrno, len) && ++which > state) {
+                                               ao2_ref(usr, -1);
                                                break;
+                                       }
+                                       ao2_ref(usr, -1);
                                }
+                               ao2_iterator_destroy(&user_iter);
+                               AST_LIST_UNLOCK(&confs);
+                               return usr ? ast_strdup(usrno) : NULL;
                        }
-                       AST_LIST_UNLOCK(&confs);
-                       return usr ? ast_strdup(usrno) : NULL;
                }
        }
 
@@ -1387,6 +1419,7 @@ static char *meetme_show_cmd(struct ast_cli_entry *e, int cmd, struct ast_cli_ar
                ast_free(cmdline);
                return CLI_SUCCESS;
        } else if (strcmp(a->argv[1], "list") == 0) {
+               struct ao2_iterator user_iter;
                int concise = (a->argc == 4 && (!strcasecmp(a->argv[3], "concise")));
                /* List all the users in a conference */
                if (AST_LIST_EMPTY(&confs)) {
@@ -1412,7 +1445,8 @@ static char *meetme_show_cmd(struct ast_cli_entry *e, int cmd, struct ast_cli_ar
                }
                /* Show all the users */
                time(&now);
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
+               user_iter = ao2_iterator_init(cnf->usercontainer, 0);
+               while((user = ao2_iterator_next(&user_iter))) {
                        hr = (now - user->jointime) / 3600;
                        min = ((now - user->jointime) % 3600) / 60;
                        sec = (now - user->jointime) % 60;
@@ -1439,7 +1473,9 @@ static char *meetme_show_cmd(struct ast_cli_entry *e, int cmd, struct ast_cli_ar
                                        user->adminflags & ADMINFLAG_T_REQUEST ? "1" : "",
                                        user->talking, hr, min, sec);
                        }
+                       ao2_ref(user, -1);
                }
+               ao2_iterator_destroy(&user_iter);
                if (!concise) {
                        ast_cli(a->fd, "%d users in that conference.\n", cnf->users);
                }
@@ -1799,7 +1835,9 @@ static int conf_free(struct ast_conference *conf)
        if (conf->recordingfilename) {
                ast_free(conf->recordingfilename);
        }
-
+       if (conf->usercontainer) {
+               ao2_ref(conf->usercontainer, -1);
+       }
        if (conf->recordingformat) {
                ast_free(conf->recordingformat);
        }
@@ -1816,13 +1854,19 @@ static void conf_queue_dtmf(const struct ast_conference *conf,
        const struct ast_conf_user *sender, struct ast_frame *f)
 {
        struct ast_conf_user *user;
+       struct ao2_iterator user_iter;
 
-       AST_LIST_TRAVERSE(&conf->userlist, user, list) {
-               if (user == sender)
+       user_iter = ao2_iterator_init(conf->usercontainer, 0);
+       while ((user = ao2_iterator_next(&user_iter))) {
+               if (user == sender) {
+                       ao2_ref(user, -1);
                        continue;
+               }
                if (ast_write(user->chan, f) < 0)
                        ast_log(LOG_WARNING, "Error writing frame to channel %s\n", user->chan->name);
+               ao2_ref(user, -1);
        }
+       ao2_iterator_destroy(&user_iter);
 }
 
 static void sla_queue_event_full(enum sla_event_type type, 
@@ -2099,6 +2143,39 @@ static void set_user_talking(struct ast_channel *chan, struct ast_conference *co
        }
 }
 
+static int user_set_kickme_cb(void *obj, void *check_admin_arg, int flags)
+{
+       struct ast_conf_user *user = obj;
+       /* actual pointer contents of check_admin_arg is irrelevant */
+
+       if (!check_admin_arg || (check_admin_arg && !ast_test_flag64(&user->userflags, CONFFLAG_ADMIN))) {
+               user->adminflags |= ADMINFLAG_KICKME;
+       }
+       return 0;
+}
+
+static int user_set_unmuted_cb(void *obj, void *check_admin_arg, int flags)
+{
+       struct ast_conf_user *user = obj;
+       /* actual pointer contents of check_admin_arg is irrelevant */
+
+       if (!check_admin_arg || !ast_test_flag64(&user->userflags, CONFFLAG_ADMIN)) {
+               user->adminflags &= ~(ADMINFLAG_MUTED | ADMINFLAG_SELFMUTED | ADMINFLAG_T_REQUEST);
+       }
+       return 0;
+}
+
+static int user_set_muted_cb(void *obj, void *check_admin_arg, int flags)
+{
+       struct ast_conf_user *user = obj;
+       /* actual pointer contents of check_admin_arg is irrelevant */
+
+       if (!check_admin_arg || !ast_test_flag64(&user->userflags, CONFFLAG_ADMIN)) {
+               user->adminflags |= ADMINFLAG_MUTED;
+       }
+       return 0;
+}
+
 static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struct ast_flags64 *confflags, char *optargs[])
 {
        struct ast_conf_user *user = NULL;
@@ -2157,8 +2234,9 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
        int setusercount = 0;
        int confsilence = 0, totalsilence = 0;
 
-       if (!(user = ast_calloc(1, sizeof(*user))))
+       if (!(user = ao2_alloc(sizeof(*user), NULL))) {
                return ret;
+       }
 
        /* Possible timeout waiting for marked user */
        if (ast_test_flag64(confflags, CONFFLAG_WAITMARKED) &&
@@ -2323,22 +2401,21 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
 
        ast_mutex_lock(&conf->playlock);
 
-       if (AST_LIST_EMPTY(&conf->userlist))
-               user->user_no = 1;
-       else
-               user->user_no = AST_LIST_LAST(&conf->userlist)->user_no + 1;
-
-       if (rt_schedule && conf->maxusers)
+       if (rt_schedule && conf->maxusers) {
                if (conf->users >= conf->maxusers) {
                        /* Sorry, but this confernce has reached the participant limit! */      
                        if (!ast_streamfile(chan, "conf-full", chan->language))
                                ast_waitstream(chan, "");
                        ast_mutex_unlock(&conf->playlock);
-                       user->user_no = 0;
                        goto outrun;
                }
+       }
 
-       AST_LIST_INSERT_TAIL(&conf->userlist, user, list);
+       ao2_lock(conf->usercontainer);
+       ao2_callback(conf->usercontainer, OBJ_NODATA, user_max_cmp, &user->user_no);
+       user->user_no++;
+       ao2_link(conf->usercontainer, user);
+       ao2_unlock(conf->usercontainer);
 
        user->chan = chan;
        user->userflags = *confflags;
@@ -3081,6 +3158,7 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
                                                if (dtmf) {
                                                        int keepplaying;
                                                        int playednamerec;
+                                                       struct ao2_iterator user_iter;
                                                        switch(dtmf) {
                                                        case '1': /* *81 Roll call */
                                                                keepplaying = 1;
@@ -3118,7 +3196,8 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
                                                                                        keepplaying = 0;
                                                                        }
                                                                }
-                                                               AST_LIST_TRAVERSE(&conf->userlist, usr, list) {
+                                                               user_iter = ao2_iterator_init(conf->usercontainer, 0);
+                                                               while((user = ao2_iterator_next(&user_iter))) {
                                                                        if (ast_fileexists(usr->namerecloc, NULL, NULL)) {
                                                                                if (keepplaying && !ast_streamfile(chan, usr->namerecloc, chan->language)) {
                                                                                        res = ast_waitstream(chan, AST_DIGIT_ANY);
@@ -3128,7 +3207,9 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
                                                                                }
                                                                                playednamerec = 1;
                                                                        }
+                                                                       ao2_ref(user, -1);
                                                                }
+                                                               ao2_iterator_destroy(&user_iter);
                                                                if (keepplaying && playednamerec && !ast_streamfile(chan, "conf-roll-callcomplete", chan->language)) {
                                                                        res = ast_waitstream(chan, AST_DIGIT_ANY);
                                                                        ast_stopstream(chan);
@@ -3141,28 +3222,19 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
                                                                        if(!ast_streamfile(chan, "conf-errormenu", chan->language))
                                                                                ast_waitstream(chan, "");
                                                                } else {
-                                                                       AST_LIST_TRAVERSE(&conf->userlist, usr, list) {
-                                                                               if (!ast_test_flag64(&usr->userflags, CONFFLAG_ADMIN))
-                                                                                       usr->adminflags |= ADMINFLAG_KICKME;
-                                                                       }
+                                                                       ao2_callback(conf->usercontainer, OBJ_NODATA, user_set_kickme_cb, &conf);
                                                                }
                                                                ast_stopstream(chan);
                                                                break;
                                                        case '3': /* *83 (Admin) mute/unmute all non-admins */
                                                                if(conf->gmuted) {
                                                                        conf->gmuted = 0;
-                                                                       AST_LIST_TRAVERSE(&conf->userlist, usr, list) {
-                                                                               if (!ast_test_flag64(&usr->userflags, CONFFLAG_ADMIN))
-                                                                                       usr->adminflags &= ~ADMINFLAG_MUTED;
-                                                                       }
+                                                                       ao2_callback(conf->usercontainer, OBJ_NODATA, user_set_unmuted_cb, &conf);
                                                                        if (!ast_streamfile(chan, "conf-now-unmuted", chan->language))
                                                                                ast_waitstream(chan, "");
                                                                } else {
                                                                        conf->gmuted = 1;
-                                                                       AST_LIST_TRAVERSE(&conf->userlist, usr, list) {
-                                                                               if (!ast_test_flag64(&usr->userflags, CONFFLAG_ADMIN))
-                                                                                       usr->adminflags |= ADMINFLAG_MUTED;
-                                                                       }
+                                                                       ao2_callback(conf->usercontainer, OBJ_NODATA, user_set_muted_cb, &conf);
                                                                        if (!ast_streamfile(chan, "conf-now-muted", chan->language))
                                                                                ast_waitstream(chan, "");
                                                                }
@@ -3278,8 +3350,11 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
                                                                }
                                                                break;
                                                        case '3': /* Eject last user */
+                                                       {
+                                                               int max_no = 0;
+                                                               ao2_callback(conf->usercontainer, OBJ_NODATA, user_max_cmp, &max_no);
                                                                menu_active = 0;
-                                                               usr = AST_LIST_LAST(&conf->userlist);
+                                                               usr = ao2_find(conf->usercontainer, &max_no, 0);
                                                                if ((usr->chan->name == chan->name) || ast_test_flag64(&usr->userflags, CONFFLAG_ADMIN)) {
                                                                        if (!ast_streamfile(chan, "conf-errormenu", chan->language)) {
                                                                                ast_waitstream(chan, "");
@@ -3287,8 +3362,10 @@ static int conf_run(struct ast_channel *chan, struct ast_conference *conf, struc
                                                                } else {
                                                                        usr->adminflags |= ADMINFLAG_KICKME;
                                                                }
+                                                               ao2_ref(user, -1);
                                                                ast_stopstream(chan);
                                                                break;  
+                                                       }
                                                        case '4':
                                                                tweak_listen_volume(user, VOL_DOWN);
                                                                break;
@@ -3610,7 +3687,9 @@ bailoutandtrynormal:
                ast_dsp_free(dsp);
        }
        
-       if (user->user_no) { /* Only cleanup users who really joined! */
+       if (!user->user_no) {
+               ao2_ref(user, -1);
+       } else { /* Only cleanup users who really joined! */
                now = ast_tvnow();
                hr = (now.tv_sec - user->jointime) / 3600;
                min = ((now.tv_sec - user->jointime) % 3600) / 60;
@@ -3647,8 +3726,8 @@ bailoutandtrynormal:
                                conf->markedusers--;
                        }
                }
-               /* Remove ourselves from the list */
-               AST_LIST_REMOVE(&conf->userlist, user, list);
+               /* Remove ourselves from the container */
+               ao2_unlink(conf->usercontainer, user); 
 
                /* Change any states */
                if (!conf->users) {
@@ -3664,7 +3743,6 @@ bailoutandtrynormal:
                        pbx_builtin_setvar_helper(chan, "MEETMEBOOKID", conf->bookid);
                }
        }
-       ast_free(user);
        AST_LIST_UNLOCK(&confs);
 
        return ret;
@@ -4267,14 +4345,60 @@ static struct ast_conf_user *find_user(struct ast_conference *conf, const char *
        
        sscanf(callerident, "%30i", &cid);
        if (conf && callerident) {
-               AST_LIST_TRAVERSE(&conf->userlist, user, list) {
-                       if (cid == user->user_no)
-                               return user;
-               }
+               user = ao2_find(conf->usercontainer, &cid, 0);
+               /* reference decremented later in admin_exec */
+               return user;
        }
        return NULL;
 }
 
+static int user_listen_volup_cb(void *obj, void *unused, int flags)
+{
+       struct ast_conf_user *user = obj;
+       tweak_listen_volume(user, VOL_UP);
+       return 0;
+}
+
+static int user_listen_voldown_cb(void *obj, void *unused, int flags)
+{
+       struct ast_conf_user *user = obj;
+       tweak_listen_volume(user, VOL_DOWN);
+       return 0;
+}
+
+static int user_talk_volup_cb(void *obj, void *unused, int flags)
+{
+       struct ast_conf_user *user = obj;
+       tweak_talk_volume(user, VOL_UP);
+       return 0;
+}
+
+static int user_talk_voldown_cb(void *obj, void *unused, int flags)
+{
+       struct ast_conf_user *user = obj;
+       tweak_talk_volume(user, VOL_DOWN);
+       return 0;
+}
+
+static int user_reset_vol_cb(void *obj, void *unused, int flags)
+{
+       struct ast_conf_user *user = obj;
+       reset_volumes(user);
+       return 0;
+}
+
+static int user_chan_cb(void *obj, void *args, int flags)
+{
+       struct ast_conf_user *user = obj;
+       const char *channel = args;
+
+       if (!strcmp(user->chan->name, channel)) {
+               return (CMP_MATCH | CMP_STOP);
+       }
+
+       return 0;
+}
+
 /*! \brief The MeetMeadmin application 
 
   MeetMeAdmin(confno, command, caller) */
@@ -4319,8 +4443,14 @@ static int admin_exec(struct ast_channel *chan, const char *data) {
 
        ast_atomic_fetchadd_int(&cnf->refcount, 1);
 
-       if (args.user)
+       if (args.user) {
                user = find_user(cnf, args.user);
+               if (!user) {
+                       ast_log(LOG_NOTICE, "Specified User not found!\n");
+                       res = -2;
+                       goto usernotfound;
+               }
+       }
 
        switch (*args.command) {
        case 76: /* L: Lock */ 
@@ -4330,118 +4460,66 @@ static int admin_exec(struct ast_channel *chan, const char *data) {
                cnf->locked = 0;
                break;
        case 75: /* K: kick all users */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list)
-                       user->adminflags |= ADMINFLAG_KICKME;
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_set_kickme_cb, NULL);
                break;
        case 101: /* e: Eject last user*/
-               user = AST_LIST_LAST(&cnf->userlist);
+       {
+               int max_no = 0;
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_max_cmp, &max_no);
+               user = ao2_find(cnf->usercontainer, &max_no, 0);
                if (!ast_test_flag64(&user->userflags, CONFFLAG_ADMIN))
                        user->adminflags |= ADMINFLAG_KICKME;
                else {
                        res = -1;
                        ast_log(LOG_NOTICE, "Not kicking last user, is an Admin!\n");
                }
+               ao2_ref(user, -1);
                break;
+       }
        case 77: /* M: Mute */ 
-               if (user) {
-                       user->adminflags |= ADMINFLAG_MUTED;
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               user->adminflags |= ADMINFLAG_MUTED;
                break;
        case 78: /* N: Mute all (non-admin) users */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       if (!ast_test_flag64(&user->userflags, CONFFLAG_ADMIN)) {
-                               user->adminflags |= ADMINFLAG_MUTED;
-                       }
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_set_muted_cb, NULL);
                break;                                  
        case 109: /* m: Unmute */ 
-               if (user) {
-                       user->adminflags &= ~(ADMINFLAG_MUTED | ADMINFLAG_SELFMUTED | ADMINFLAG_T_REQUEST);
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               user->adminflags &= ~(ADMINFLAG_MUTED | ADMINFLAG_SELFMUTED | ADMINFLAG_T_REQUEST);
                break;
        case 110: /* n: Unmute all users */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       user->adminflags &= ~(ADMINFLAG_MUTED | ADMINFLAG_SELFMUTED | ADMINFLAG_T_REQUEST);
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_set_unmuted_cb, NULL);
                break;
        case 107: /* k: Kick user */ 
-               if (user) {
-                       user->adminflags |= ADMINFLAG_KICKME;
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               user->adminflags |= ADMINFLAG_KICKME;
                break;
        case 118: /* v: Lower all users listen volume */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       tweak_listen_volume(user, VOL_DOWN);
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_listen_voldown_cb, NULL);
                break;
        case 86: /* V: Raise all users listen volume */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       tweak_listen_volume(user, VOL_UP);
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_listen_volup_cb, NULL);
                break;
        case 115: /* s: Lower all users speaking volume */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       tweak_talk_volume(user, VOL_DOWN);
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_talk_voldown_cb, NULL);
                break;
        case 83: /* S: Raise all users speaking volume */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       tweak_talk_volume(user, VOL_UP);
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_talk_volup_cb, NULL);
                break;
        case 82: /* R: Reset all volume levels */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                       reset_volumes(user);
-               }
+               ao2_callback(cnf->usercontainer, OBJ_NODATA, user_reset_vol_cb, NULL);
                break;
        case 114: /* r: Reset user's volume level */
-               if (user) {
-                       reset_volumes(user);
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               reset_volumes(user);
                break;
        case 85: /* U: Raise user's listen volume */
-               if (user) {
-                       tweak_listen_volume(user, VOL_UP);
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               tweak_listen_volume(user, VOL_UP);
                break;
        case 117: /* u: Lower user's listen volume */
-               if (user) {
-                       tweak_listen_volume(user, VOL_DOWN);
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               tweak_listen_volume(user, VOL_DOWN);
                break;
        case 84: /* T: Raise user's talk volume */
-               if (user) {
-                       tweak_talk_volume(user, VOL_UP);
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               tweak_talk_volume(user, VOL_UP);
                break;
        case 116: /* t: Lower user's talk volume */
-               if (user) {
-                       tweak_talk_volume(user, VOL_DOWN);
-               } else {
-                       res = -2;
-                       ast_log(LOG_NOTICE, "Specified User not found!\n");
-               }
+               tweak_talk_volume(user, VOL_DOWN);
                break;
        case 'E': /* E: Extend conference */
                if (rt_extend_conf(args.confno)) {
@@ -4450,6 +4528,11 @@ static int admin_exec(struct ast_channel *chan, const char *data) {
                break;
        }
 
+       if (args.user) {
+               /* decrement reference from find_user */
+               ao2_ref(user, -1);
+       }
+usernotfound:
        AST_LIST_UNLOCK(&confs);
 
        dispose_conf(cnf);
@@ -4489,9 +4572,8 @@ static int channel_admin_exec(struct ast_channel *chan, const char *data) {
 
        AST_LIST_LOCK(&confs);
        AST_LIST_TRAVERSE(&confs, conf, list) {
-               AST_LIST_TRAVERSE(&conf->userlist, user, list) {
-                       if (!strcmp(user->chan->name, args.channel))
-                               break;
+               if ((user = ao2_callback(conf->usercontainer, 0, user_chan_cb, args.channel))) {
+                       break;
                }
        }
        
@@ -4516,7 +4598,7 @@ static int channel_admin_exec(struct ast_channel *chan, const char *data) {
                        ast_log(LOG_WARNING, "Unknown MeetMeChannelAdmin command '%s'\n", args.command);
                        break;
        }
-
+       ao2_ref(user, -1);
        AST_LIST_UNLOCK(&confs);
        
        return 0;
@@ -4560,9 +4642,7 @@ static int meetmemute(struct mansession *s, const struct message *m, int mute)
                return 0;
        }
 
-       AST_LIST_TRAVERSE(&conf->userlist, user, list)
-               if (user->user_no == userno)
-                       break;
+       user = ao2_find(conf->usercontainer, &userno, 0);
 
        if (!user) {
                AST_LIST_UNLOCK(&confs);
@@ -4579,6 +4659,7 @@ static int meetmemute(struct mansession *s, const struct message *m, int mute)
 
        ast_log(LOG_NOTICE, "Requested to %smute conf %s user %d userchan %s uniqueid %s\n", mute ? "" : "un", conf->confno, user->user_no, user->chan->name, user->chan->uniqueid);
 
+       ao2_ref(user, -1);
        astman_send_ack(s, m, mute ? "User muted" : "User unmuted");
        return 0;
 }
@@ -4600,6 +4681,7 @@ static int action_meetmelist(struct mansession *s, const struct message *m)
        char idText[80] = "";
        struct ast_conference *cnf;
        struct ast_conf_user *user;
+       struct ao2_iterator user_iter;
        int total = 0;
 
        if (!ast_strlen_zero(actionid))
@@ -4615,12 +4697,13 @@ static int action_meetmelist(struct mansession *s, const struct message *m)
        /* Find the right conference */
        AST_LIST_LOCK(&confs);
        AST_LIST_TRAVERSE(&confs, cnf, list) {
+               user_iter = ao2_iterator_init(cnf->usercontainer, 0);
                /* If we ask for one particular, and this isn't it, skip it */
                if (!ast_strlen_zero(conference) && strcmp(cnf->confno, conference))
                        continue;
 
                /* Show all the users */
-               AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
+               while ((user = ao2_iterator_next(&user_iter))) {
                        total++;
                        astman_append(s,
                        "Event: MeetmeList\r\n"
@@ -4647,7 +4730,9 @@ static int action_meetmelist(struct mansession *s, const struct message *m)
                        ast_test_flag64(&user->userflags, CONFFLAG_MARKEDUSER) ? "Yes" : "No",
                        user->adminflags & ADMINFLAG_MUTED ? "By admin" : user->adminflags & ADMINFLAG_SELFMUTED ? "By self" : "No",
                        user->talking > 0 ? "Yes" : user->talking == 0 ? "No" : "Not monitored"); 
+                       ao2_ref(user, -1);
                }
+               ao2_iterator_destroy(&user_iter);
        }
        AST_LIST_UNLOCK(&confs);
        /* Send final confirmation */
@@ -6766,6 +6851,48 @@ AST_DATA_STRUCTURE(ast_conference, MEETME_DATA_EXPORT);
 
 AST_DATA_STRUCTURE(ast_conf_user, MEETME_USER_DATA_EXPORT);
 
+static int user_add_provider_cb(void *obj, void *arg, int flags)
+{
+       struct ast_data *data_meetme_user;
+       struct ast_data *data_meetme_user_channel;
+       struct ast_data *data_meetme_user_volume;
+
+       struct ast_conf_user *user = obj;
+       struct ast_data *data_meetme_users = arg;
+
+       data_meetme_user = ast_data_add_node(data_meetme_users, "user");
+       if (!data_meetme_user) {
+               return 0;
+       }
+       /* user structure */
+       ast_data_add_structure(ast_conf_user, data_meetme_user, user);
+
+       /* user's channel */
+       data_meetme_user_channel = ast_data_add_node(data_meetme_user, "channel");
+       if (!data_meetme_user_channel) {
+               return 0;
+       }
+
+       ast_channel_data_add_structure(data_meetme_user_channel, user->chan, 1);
+
+       /* volume structure */
+       data_meetme_user_volume = ast_data_add_node(data_meetme_user, "listen-volume");
+       if (!data_meetme_user_volume) {
+               return 0;
+       }
+       ast_data_add_int(data_meetme_user_volume, "desired", user->listen.desired);
+       ast_data_add_int(data_meetme_user_volume, "actual", user->listen.actual);
+
+       data_meetme_user_volume = ast_data_add_node(data_meetme_user, "talk-volume");
+       if (!data_meetme_user_volume) {
+               return 0;
+       }
+       ast_data_add_int(data_meetme_user_volume, "desired", user->talk.desired);
+       ast_data_add_int(data_meetme_user_volume, "actual", user->talk.actual);
+
+       return 0;
+}
+
 /*!
  * \internal
  * \brief Implements the meetme data provider.
@@ -6774,9 +6901,7 @@ static int meetme_data_provider_get(const struct ast_data_search *search,
        struct ast_data *data_root)
 {
        struct ast_conference *cnf;
-       struct ast_conf_user *user;
-       struct ast_data *data_meetme, *data_meetme_users, *data_meetme_user;
-       struct ast_data *data_meetme_user_channel, *data_meetme_user_volume;
+       struct ast_data *data_meetme, *data_meetme_users;
 
        AST_LIST_LOCK(&confs);
        AST_LIST_TRAVERSE(&confs, cnf, list) {
@@ -6787,44 +6912,14 @@ static int meetme_data_provider_get(const struct ast_data_search *search,
 
                ast_data_add_structure(ast_conference, data_meetme, cnf);
 
-               if (!AST_LIST_EMPTY(&cnf->userlist)) {
+               if (ao2_container_count(cnf->usercontainer)) {
                        data_meetme_users = ast_data_add_node(data_meetme, "users");
                        if (!data_meetme_users) {
                                ast_data_remove_node(data_root, data_meetme);
                                continue;
                        }
 
-                       AST_LIST_TRAVERSE(&cnf->userlist, user, list) {
-                               data_meetme_user = ast_data_add_node(data_meetme_users, "user");
-                               if (!data_meetme_user) {
-                                       continue;
-                               }
-                               /* user structure. */
-                               ast_data_add_structure(ast_conf_user, data_meetme_user, user);
-
-                               /* user's channel */
-                               data_meetme_user_channel = ast_data_add_node(data_meetme_user, "channel");
-                               if (!data_meetme_user_channel) {
-                                       continue;
-                               }
-
-                               ast_channel_data_add_structure(data_meetme_user_channel, user->chan, 1);
-
-                               /* volume structure */
-                               data_meetme_user_volume = ast_data_add_node(data_meetme_user, "listen-volume");
-                               if (!data_meetme_user_volume) {
-                                       continue;
-                               }
-                               ast_data_add_int(data_meetme_user_volume, "desired", user->listen.desired);
-                               ast_data_add_int(data_meetme_user_volume, "actual", user->listen.actual);
-
-                               data_meetme_user_volume = ast_data_add_node(data_meetme_user, "talk-volume");
-                               if (!data_meetme_user_volume) {
-                                       continue;
-                               }
-                               ast_data_add_int(data_meetme_user_volume, "desired", user->talk.desired);
-                               ast_data_add_int(data_meetme_user_volume, "actual", user->talk.actual);
-                       }
+                       ao2_callback(cnf->usercontainer, OBJ_NODATA, user_add_provider_cb, data_meetme_users); 
                }
 
                if (!ast_data_search_match(search, data_meetme)) {