diff --git a/apps/app_chanspy.c b/apps/app_chanspy.c
index 50d8d63210ec5e4905cbe964321b282fb3eaf7e0..4814f4ce5db4ce75bb6efd201da7f91cdb98ca99 100644
--- a/apps/app_chanspy.c
+++ b/apps/app_chanspy.c
@@ -506,18 +506,24 @@ static struct ast_generator spygen = {
static int start_spying(struct ast_autochan *autochan, const char *spychan_name, struct ast_audiohook *audiohook, struct ast_flags *flags)
{
+ int res;
+
+ ast_autochan_channel_lock(autochan);
ast_log(LOG_NOTICE, "Attaching %s to %s\n", spychan_name, ast_channel_name(autochan->chan));
- if(ast_test_flag(flags, OPTION_READONLY)) {
+
+ if (ast_test_flag(flags, OPTION_READONLY)) {
ast_set_flag(audiohook, AST_AUDIOHOOK_MUTE_WRITE);
} else {
ast_set_flag(audiohook, AST_AUDIOHOOK_TRIGGER_SYNC);
}
- if(ast_test_flag(flags, OPTION_LONG_QUEUE)) {
+ if (ast_test_flag(flags, OPTION_LONG_QUEUE)) {
ast_debug(9, "Using a long queue to store audio frames in spy audiohook\n");
} else {
ast_set_flag(audiohook, AST_AUDIOHOOK_SMALL_QUEUE);
}
- return ast_audiohook_attach(autochan->chan, audiohook);
+ res = ast_audiohook_attach(autochan->chan, audiohook);
+ ast_autochan_channel_unlock(autochan);
+ return res;
}
static void change_spy_mode(const char digit, struct ast_flags *flags)
@@ -601,8 +607,14 @@ static int attach_barge(struct ast_autochan *spyee_autochan,
{
int retval = 0;
struct ast_autochan *internal_bridge_autochan;
- RAII_VAR(struct ast_channel *, bridged, ast_channel_bridge_peer(spyee_autochan->chan), ast_channel_cleanup);
+ struct ast_channel *spyee_chan;
+ RAII_VAR(struct ast_channel *, bridged, NULL, ast_channel_cleanup);
+ ast_autochan_channel_lock(spyee_autochan);
+ spyee_chan = ast_channel_ref(spyee_autochan->chan);
+ ast_autochan_channel_unlock(spyee_autochan);
+ bridged = ast_channel_bridge_peer(spyee_chan);
+ ast_channel_unref(spyee_chan);
if (!bridged) {
return -1;
}
@@ -614,12 +626,10 @@ static int attach_barge(struct ast_autochan *spyee_autochan,
return -1;
}
- ast_autochan_channel_lock(internal_bridge_autochan);
if (start_spying(internal_bridge_autochan, spyer_name, bridge_whisper_audiohook, flags)) {
ast_log(LOG_WARNING, "Unable to attach barge audiohook on spyee '%s'. Barge mode disabled.\n", name);
retval = -1;
}
- ast_autochan_channel_unlock(internal_bridge_autochan);
*spyee_bridge_autochan = internal_bridge_autochan;
@@ -639,21 +649,25 @@ static int channel_spy(struct ast_channel *chan, struct ast_autochan *spyee_auto
struct ast_autochan *spyee_bridge_autochan = NULL;
const char *spyer_name;
- if (ast_check_hangup(chan) || ast_check_hangup(spyee_autochan->chan) ||
- ast_test_flag(ast_channel_flags(spyee_autochan->chan), AST_FLAG_ZOMBIE)) {
+ ast_channel_lock(chan);
+ if (ast_check_hangup(chan)) {
+ ast_channel_unlock(chan);
return 0;
}
-
- ast_channel_lock(chan);
spyer_name = ast_strdupa(ast_channel_name(chan));
ast_channel_unlock(chan);
ast_autochan_channel_lock(spyee_autochan);
+ if (ast_check_hangup(spyee_autochan->chan)
+ || ast_test_flag(ast_channel_flags(spyee_autochan->chan), AST_FLAG_ZOMBIE)) {
+ ast_autochan_channel_unlock(spyee_autochan);
+ return 0;
+ }
name = ast_strdupa(ast_channel_name(spyee_autochan->chan));
- ast_autochan_channel_unlock(spyee_autochan);
ast_verb(2, "Spying on channel %s\n", name);
publish_chanspy_message(chan, spyee_autochan->chan, 1);
+ ast_autochan_channel_unlock(spyee_autochan);
memset(&csth, 0, sizeof(csth));
ast_copy_flags(&csth.flags, flags, AST_FLAGS_ALL);
@@ -845,7 +859,7 @@ static int channel_spy(struct ast_channel *chan, struct ast_autochan *spyee_auto
}
static struct ast_autochan *next_channel(struct ast_channel_iterator *iter,
- struct ast_autochan *autochan, struct ast_channel *chan)
+ struct ast_channel *chan)
{
struct ast_channel *next;
struct ast_autochan *autochan_store;
@@ -982,11 +996,12 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
waitms = 100;
num_spyed_upon = 0;
- for (autochan = next_channel(iter, autochan, chan);
- autochan;
- prev = autochan->chan, ast_autochan_destroy(autochan),
- autochan = next_autochan ? next_autochan :
- next_channel(iter, autochan, chan), next_autochan = NULL) {
+ for (autochan = next_channel(iter, chan);
+ autochan;
+ prev = autochan->chan,
+ ast_autochan_destroy(autochan),
+ autochan = next_autochan ?: next_channel(iter, chan),
+ next_autochan = NULL) {
int igrp = !mygroup;
int ienf = !myenforced;
@@ -1000,13 +1015,19 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
break;
}
- if (ast_test_flag(flags, OPTION_BRIDGED) && !ast_channel_is_bridged(autochan->chan)) {
+ ast_autochan_channel_lock(autochan);
+ if (ast_test_flag(flags, OPTION_BRIDGED)
+ && !ast_channel_is_bridged(autochan->chan)) {
+ ast_autochan_channel_unlock(autochan);
continue;
}
- if (ast_check_hangup(autochan->chan) || ast_test_flag(ast_channel_flags(autochan->chan), AST_FLAG_SPYING)) {
+ if (ast_check_hangup(autochan->chan)
+ || ast_test_flag(ast_channel_flags(autochan->chan), AST_FLAG_SPYING)) {
+ ast_autochan_channel_unlock(autochan);
continue;
}
+ ast_autochan_channel_unlock(autochan);
if (mygroup) {
int num_groups = 0;
@@ -1024,11 +1045,13 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
/* Before dahdi scan was part of chanspy, it would use the "GROUP" variable
* rather than "SPYGROUP", this check is done to preserve expected behavior */
+ ast_autochan_channel_lock(autochan);
if (ast_test_flag(flags, OPTION_DAHDI_SCAN)) {
group = pbx_builtin_getvar_helper(autochan->chan, "GROUP");
} else {
group = pbx_builtin_getvar_helper(autochan->chan, "SPYGROUP");
}
+ ast_autochan_channel_unlock(autochan);
if (!ast_strlen_zero(group)) {
ast_copy_string(dup_group, group, sizeof(dup_group));
@@ -1056,7 +1079,9 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
snprintf(buffer, sizeof(buffer) - 1, ":%s:", myenforced);
+ ast_autochan_channel_lock(autochan);
ast_copy_string(ext + 1, ast_channel_name(autochan->chan), sizeof(ext) - 1);
+ ast_autochan_channel_unlock(autochan);
if ((end = strchr(ext, '-'))) {
*end++ = ':';
*end = '\0';
@@ -1078,7 +1103,9 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
char *ptr, *s;
strcpy(peer_name, "spy-");
+ ast_autochan_channel_lock(autochan);
strncat(peer_name, ast_channel_name(autochan->chan), AST_NAME_STRLEN - 4 - 1);
+ ast_autochan_channel_unlock(autochan);
if ((ptr = strchr(peer_name, '/'))) {
*ptr++ = '\0';
for (s = peer_name; s < ptr; s++) {
@@ -1143,12 +1170,14 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
next = ast_channel_unref(next);
} else {
/* stay on this channel, if it is still valid */
+ ast_autochan_channel_lock(autochan);
if (!ast_check_hangup(autochan->chan)) {
next_autochan = ast_autochan_setup(autochan->chan);
} else {
/* the channel is gone */
next_autochan = NULL;
}
+ ast_autochan_channel_unlock(autochan);
}
} else if (res == 0 && ast_test_flag(flags, OPTION_EXITONHANGUP)) {
ast_autochan_destroy(autochan);
diff --git a/apps/app_mixmonitor.c b/apps/app_mixmonitor.c
index a5a00cc4efcd08f6e689a5ae0d6a8ac0d74388bd..3258b301fa09d78339cc5019f3ee05ac519e9e34 100644
--- a/apps/app_mixmonitor.c
+++ b/apps/app_mixmonitor.c
@@ -617,6 +617,16 @@ static void mixmonitor_save_prep(struct mixmonitor *mixmonitor, char *filename,
}
}
+static int mixmonitor_autochan_is_bridged(struct ast_autochan *autochan)
+{
+ int is_bridged;
+
+ ast_autochan_channel_lock(autochan);
+ is_bridged = ast_channel_is_bridged(autochan->chan);
+ ast_autochan_channel_unlock(autochan);
+ return is_bridged;
+}
+
static void *mixmonitor_thread(void *obj)
{
struct mixmonitor *mixmonitor = obj;
@@ -674,8 +684,7 @@ static void *mixmonitor_thread(void *obj)
ast_audiohook_unlock(&mixmonitor->audiohook);
if (!ast_test_flag(mixmonitor, MUXFLAG_BRIDGED)
- || (mixmonitor->autochan->chan
- && ast_channel_is_bridged(mixmonitor->autochan->chan))) {
+ || mixmonitor_autochan_is_bridged(mixmonitor->autochan)) {
ast_mutex_lock(&mixmonitor->mixmonitor_ds->lock);
/* Write out the frame(s) */
@@ -724,11 +733,11 @@ static void *mixmonitor_thread(void *obj)
ast_audiohook_unlock(&mixmonitor->audiohook);
- ast_autochan_channel_lock(mixmonitor->autochan);
if (ast_test_flag(mixmonitor, MUXFLAG_BEEP_STOP)) {
+ ast_autochan_channel_lock(mixmonitor->autochan);
ast_stream_and_wait(mixmonitor->autochan->chan, "beep", "");
+ ast_autochan_channel_unlock(mixmonitor->autochan);
}
- ast_autochan_channel_unlock(mixmonitor->autochan);
ast_autochan_destroy(mixmonitor->autochan);
@@ -800,11 +809,11 @@ static int setup_mixmonitor_ds(struct mixmonitor *mixmonitor, struct ast_channel
return -1;
}
- ast_autochan_channel_lock(mixmonitor->autochan);
if (ast_test_flag(mixmonitor, MUXFLAG_BEEP_START)) {
+ ast_autochan_channel_lock(mixmonitor->autochan);
ast_stream_and_wait(mixmonitor->autochan->chan, "beep", "");
+ ast_autochan_channel_unlock(mixmonitor->autochan);
}
- ast_autochan_channel_unlock(mixmonitor->autochan);
mixmonitor_ds->samp_rate = 8000;
mixmonitor_ds->audiohook = &mixmonitor->audiohook;
diff --git a/include/asterisk/autochan.h b/include/asterisk/autochan.h
index 319c203ab1557d74da6c3ded4de388cfb33dcbf7..128377b57bf296f94c29154648fabb134e847220 100644
--- a/include/asterisk/autochan.h
+++ b/include/asterisk/autochan.h
@@ -32,6 +32,7 @@
struct ast_autochan {
struct ast_channel *chan;
AST_LIST_ENTRY(ast_autochan) list;
+ ast_mutex_t lock;
};
/*!
@@ -61,19 +62,24 @@ struct ast_autochan {
* ast_autochan_channel_lock and ast_autochan_channel_unlock. An attempt to lock
* the autochan->chan directly may result in it being changed after you've
* retrieved the value of chan, but before you've had a chance to lock it.
- * First when chan is locked, the autochan structure is guaranteed to keep the
+ * While chan is locked, the autochan structure is guaranteed to keep the
* same channel.
*/
+/*!
+ * \brief Lock the autochan's channel lock.
+ *
+ * \note We must do deadlock avoidance because the channel lock is
+ * superior to the autochan lock in locking order.
+ */
#define ast_autochan_channel_lock(autochan) \
do { \
- struct ast_channel *autochan_chan = autochan->chan; \
- ast_channel_lock(autochan_chan); \
- if (autochan->chan == autochan_chan) { \
- break; \
+ ast_mutex_lock(&(autochan)->lock); \
+ while (ast_channel_trylock((autochan)->chan)) { \
+ DEADLOCK_AVOIDANCE(&(autochan)->lock); \
} \
- ast_channel_unlock(autochan_chan); \
- } while (1)
+ ast_mutex_unlock(&(autochan)->lock); \
+ } while (0)
#define ast_autochan_channel_unlock(autochan) \
ast_channel_unlock(autochan->chan)
diff --git a/main/autochan.c b/main/autochan.c
index c7e5c00425891af61bf573cb5295ec6c1fa047f0..68aeaf804ae50c26d423f758700233b9b70ca082 100644
--- a/main/autochan.c
+++ b/main/autochan.c
@@ -46,15 +46,18 @@ struct ast_autochan *ast_autochan_setup(struct ast_channel *chan)
if (!(autochan = ast_calloc(1, sizeof(*autochan)))) {
return NULL;
}
+ ast_mutex_init(&autochan->lock);
autochan->chan = ast_channel_ref(chan);
- ast_channel_lock(autochan->chan); /* autochan is still private, no need for ast_autochan_channel_lock() */
+ ast_debug(1, "Created autochan %p to hold channel %s (%p)\n",
+ autochan, ast_channel_name(chan), chan);
+
+ /* autochan is still private, no need for ast_autochan_channel_lock() */
+ ast_channel_lock(autochan->chan);
AST_LIST_INSERT_TAIL(ast_channel_autochans(autochan->chan), autochan, list);
ast_channel_unlock(autochan->chan);
- ast_debug(1, "Created autochan %p to hold channel %s (%p)\n", autochan, ast_channel_name(chan), chan);
-
return autochan;
}
@@ -75,6 +78,8 @@ void ast_autochan_destroy(struct ast_autochan *autochan)
autochan->chan = ast_channel_unref(autochan->chan);
+ ast_mutex_destroy(&autochan->lock);
+
ast_free(autochan);
}
@@ -84,13 +89,16 @@ void ast_autochan_new_channel(struct ast_channel *old_chan, struct ast_channel *
AST_LIST_APPEND_LIST(ast_channel_autochans(new_chan), ast_channel_autochans(old_chan), list);
+ /* Deadlock avoidance is not needed since the channels are already locked. */
AST_LIST_TRAVERSE(ast_channel_autochans(new_chan), autochan, list) {
+ ast_mutex_lock(&autochan->lock);
if (autochan->chan == old_chan) {
- autochan->chan = ast_channel_unref(old_chan);
autochan->chan = ast_channel_ref(new_chan);
+ ast_channel_unref(old_chan);
ast_debug(1, "Autochan %p used to hold channel %s (%p) but now holds channel %s (%p)\n",
autochan, ast_channel_name(old_chan), old_chan, ast_channel_name(new_chan), new_chan);
}
+ ast_mutex_unlock(&autochan->lock);
}
}