From: Terry Wilson Date: Tue, 22 May 2012 17:21:51 +0000 (+0000) Subject: Fix race condition for CEL LINKEDID_END event X-Git-Tag: 10.6.0-rc1~30 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6900424762f577fe7168e65a39437ce92432a0bb;p=thirdparty%2Fasterisk.git Fix race condition for CEL LINKEDID_END event This patch fixes to situations that could cause the CEL LINKEDID_END event to be missed. 1) During a core stop gracefully, modules are unloaded when ast_active_channels == 0. The LINKDEDID_END event fires during the channel destructor. This means that occasionally, the cel_* module will be unloaded before the channel is destroyed. It seemed generally useful to wait until the refcount of all channels == 0 before unloading, so I added a channel counter and used it in the shutdown code. 2) During a masquerade, ast_channel_change_linkedid is called. It calls ast_cel_check_retire_linkedid which unrefs the linkedid in the linkedids container in cel.c. It didn't ref the new linkedid. Now it does. Review: https://reviewboard.asterisk.org/r/1900/ ........ Merged revisions 367292 from http://svn.asterisk.org/svn/asterisk/branches/1.8 git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@367299 65c4cc65-6c06-0410-ace0-fbb531ad65f3 --- diff --git a/include/asterisk/cel.h b/include/asterisk/cel.h index b388ffd9b5..25a3a4af1d 100644 --- a/include/asterisk/cel.h +++ b/include/asterisk/cel.h @@ -187,6 +187,15 @@ const char *ast_cel_get_ama_flag_name(enum ast_cel_ama_flag flag); */ void ast_cel_check_retire_linkedid(struct ast_channel *chan); +/*! + * \brief Inform CEL that a new linkedid is being used + * \since 11 + * + * \retval -1 error + * \retval 0 success + */ +int ast_cel_linkedid_ref(const char *linkedid); + /*! * \brief Create a fake channel from data in a CEL event * diff --git a/include/asterisk/channel.h b/include/asterisk/channel.h index 8a371a11f3..4e16b5ae7d 100644 --- a/include/asterisk/channel.h +++ b/include/asterisk/channel.h @@ -2166,9 +2166,12 @@ void ast_begin_shutdown(int hangup); /*! Cancels an existing shutdown and returns to normal operation */ void ast_cancel_shutdown(void); -/*! \return number of active/allocated channels */ +/*! \return number of channels available for lookup */ int ast_active_channels(void); +/*! \return the number of channels not yet destroyed */ +int ast_undestroyed_channels(void); + /*! \return non-zero if Asterisk is being shut down */ int ast_shutting_down(void); diff --git a/main/asterisk.c b/main/asterisk.c index ac30958c31..3ebcebe540 100644 --- a/main/asterisk.c +++ b/main/asterisk.c @@ -1701,7 +1701,7 @@ static int can_safely_quit(shutdown_nice_t niceness, int restart) for (;;) { time(&e); /* Wait up to 15 seconds for all channels to go away */ - if ((e - s) > 15 || !ast_active_channels() || shuttingdown != niceness) { + if ((e - s) > 15 || !ast_undestroyed_channels() || shuttingdown != niceness) { break; } /* Sleep 1/10 of a second */ @@ -1715,7 +1715,7 @@ static int can_safely_quit(shutdown_nice_t niceness, int restart) ast_verbose("Waiting for inactivity to perform %s...\n", restart ? "restart" : "halt"); } for (;;) { - if (!ast_active_channels() || shuttingdown != niceness) { + if (!ast_undestroyed_channels() || shuttingdown != niceness) { break; } sleep(1); diff --git a/main/cel.c b/main/cel.c index 023fd571a9..ce9a15f97d 100644 --- a/main/cel.c +++ b/main/cel.c @@ -464,6 +464,31 @@ struct ast_channel *ast_cel_fabricate_channel_from_event(const struct ast_event return tchan; } +int ast_cel_linkedid_ref(const char *linkedid) +{ + char *lid; + + if (ast_strlen_zero(linkedid)) { + ast_log(LOG_ERROR, "The linkedid should never be empty\n"); + return -1; + } + + if (!(lid = ao2_find(linkedids, (void *) linkedid, OBJ_POINTER))) { + if (!(lid = ao2_alloc(strlen(linkedid) + 1, NULL))) { + return -1; + } + strcpy(lid, linkedid); + if (!ao2_link(linkedids, lid)) { + ao2_ref(lid, -1); + return -1; + } + /* Leave both the link and the alloc refs to show a count of 1 + the link */ + } + /* If we've found, go ahead and keep the ref to increment count of how many channels + * have this linkedid. We'll clean it up in check_retire */ + return 0; +} + int ast_cel_report_event(struct ast_channel *chan, enum ast_cel_event_type event_type, const char *userdefevname, const char *extra, struct ast_channel *peer2) { @@ -480,22 +505,10 @@ int ast_cel_report_event(struct ast_channel *chan, enum ast_cel_event_type event /* Record the linkedid of new channels if we are tracking LINKEDID_END even if we aren't * reporting on CHANNEL_START so we can track when to send LINKEDID_END */ if (cel_enabled && ast_cel_track_event(AST_CEL_LINKEDID_END) && event_type == AST_CEL_CHANNEL_START && chan->linkedid) { - char *lid; - if (!(lid = ao2_find(linkedids, (void *) chan->linkedid, OBJ_POINTER))) { - if (!(lid = ao2_alloc(strlen(chan->linkedid) + 1, NULL))) { - ast_mutex_unlock(&reload_lock); - return -1; - } - strcpy(lid, chan->linkedid); - if (!ao2_link(linkedids, lid)) { - ao2_ref(lid, -1); - ast_mutex_unlock(&reload_lock); - return -1; - } - /* Leave both the link and the alloc refs to show a count of 1 + the link */ + if (ast_cel_linkedid_ref(chan->linkedid)) { + ast_mutex_unlock(&reload_lock); + return -1; } - /* If we've found, go ahead and keep the ref to increment count of how many channels - * have this linkedid. We'll clean it up in check_retire */ } if (!cel_enabled || !ast_cel_track_event(event_type)) { diff --git a/main/channel.c b/main/channel.c index 2bb4a20e6a..b3a51bafd7 100644 --- a/main/channel.c +++ b/main/channel.c @@ -93,6 +93,7 @@ struct ast_epoll_data { static int shutting_down; static int uniqueint; +static int chancount; unsigned long global_fin, global_fout; @@ -833,6 +834,11 @@ int ast_active_channels(void) return channels ? ao2_container_count(channels) : 0; } +int ast_undestroyed_channels(void) +{ + return ast_atomic_fetchadd_int(&chancount, 0); +} + /*! \brief Cancel a shutdown in progress */ void ast_cancel_shutdown(void) { @@ -1310,6 +1316,7 @@ __ast_channel_alloc_ap(int needqueue, int state, const char *cid_num, const char ast_cdr_init(tmp->cdr, tmp); ast_cdr_start(tmp->cdr); + ast_atomic_fetchadd_int(&chancount, +1); ast_cel_report_event(tmp, AST_CEL_CHANNEL_START, NULL, NULL, NULL); headp = &tmp->varshead; @@ -2507,6 +2514,7 @@ static void ast_channel_destructor(void *obj) } chan->nativeformats = ast_format_cap_destroy(chan->nativeformats); + ast_atomic_fetchadd_int(&chancount, -1); } /*! \brief Free a dummy channel structure */ @@ -6460,15 +6468,17 @@ static const char *oldest_linkedid(const char *a, const char *b) * see if the channel's old linkedid is now being retired */ static void ast_channel_change_linkedid(struct ast_channel *chan, const char *linkedid) { + ast_assert(linkedid != NULL); /* if the linkedid for this channel is being changed from something, check... */ - if (!ast_strlen_zero(chan->linkedid) && 0 != strcmp(chan->linkedid, linkedid)) { - ast_cel_check_retire_linkedid(chan); + if (!strcmp(chan->linkedid, linkedid)) { + return; } + ast_cel_check_retire_linkedid(chan); ast_string_field_set(chan, linkedid, linkedid); + ast_cel_linkedid_ref(linkedid); } - /*! \brief Propagate the oldest linkedid between associated channels