[asterisk-commits] bridge.c: Fixed race condition during attended transfer (asterisk[13])
SVN commits to the Asterisk project
asterisk-commits at lists.digium.com
Mon Jul 13 14:51:22 CDT 2015
Mark Michelson has submitted this change and it was merged.
Change subject: bridge.c: Fixed race condition during attended transfer
......................................................................
bridge.c: Fixed race condition during attended transfer
During an attended transfer a thread is started that handles imparting the
bridge channel. From the start of the thread to when the bridge channel is
ready exists a gap that can potentially cause problems (for instance, the
channel being swapped is hung up before the replacement channel enters the
bridge thus stopping the transfer). This patch adds a condition that waits
for the impart thread to get to a point of acceptable readiness before
allowing the initiating thread to continue.
ASTERISK-24782
Reported by: John Bigelow
Change-Id: I08fe33a2560da924e676df55b181e46fca604577
---
M include/asterisk/bridge.h
M include/asterisk/bridge_channel_internal.h
M main/bridge.c
M main/bridge_channel.c
4 files changed, 109 insertions(+), 9 deletions(-)
Approvals:
Mark Michelson: Looks good to me, approved
Richard Mudgett: Looks good to me, but someone else must approve
Anonymous Coward #1000019: Verified
diff --git a/include/asterisk/bridge.h b/include/asterisk/bridge.h
index 8fa0f36..fc37262 100644
--- a/include/asterisk/bridge.h
+++ b/include/asterisk/bridge.h
@@ -509,6 +509,8 @@
* \param features Bridge features structure.
* \param flags defined by enum ast_bridge_impart_flags.
*
+ * \note The given bridge must be unlocked when calling this function.
+ *
* \note The features parameter must be NULL or obtained by
* ast_bridge_features_new(). You must not dereference features
* after calling even if the call fails.
diff --git a/include/asterisk/bridge_channel_internal.h b/include/asterisk/bridge_channel_internal.h
index 71892f5..e3fb73d 100644
--- a/include/asterisk/bridge_channel_internal.h
+++ b/include/asterisk/bridge_channel_internal.h
@@ -130,10 +130,47 @@
void bridge_channel_internal_pull(struct ast_bridge_channel *bridge_channel);
/*!
+ * \brief Internal bridge channel wait condition and associated result.
+ */
+struct bridge_channel_internal_cond {
+ /*! Lock for the data structure */
+ ast_mutex_t lock;
+ /*! Wait condition */
+ ast_cond_t cond;
+ /*! Wait until done */
+ int done;
+ /*! The bridge channel */
+ struct ast_bridge_channel *bridge_channel;
+};
+
+/*!
+ * \internal
+ * \brief Wait for the expected signal.
+ * \since 13.5.0
+ *
+ * \param cond the wait object
+ *
+ * \return Nothing
+ */
+void bridge_channel_internal_wait(struct bridge_channel_internal_cond *cond);
+
+/*!
+ * \internal
+ * \brief Signal the condition wait.
+ * \since 13.5.0
+ *
+ * \param cond the wait object
+ *
+ * \return Nothing
+ */
+void bridge_channel_internal_signal(struct bridge_channel_internal_cond *cond);
+
+/*!
* \internal
* \brief Join the bridge_channel to the bridge (blocking)
*
* \param bridge_channel The Channel in the bridge
+ * \param cond data used for signaling
*
* \note The bridge_channel->swap holds a channel reference for the swap
* channel going into the bridging system. The ref ensures that the swap
@@ -148,7 +185,8 @@
* \retval 0 bridge channel successfully joined the bridge
* \retval -1 bridge channel failed to join the bridge
*/
-int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel);
+int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel,
+ struct bridge_channel_internal_cond *cond);
/*!
* \internal
diff --git a/main/bridge.c b/main/bridge.c
index 75cd671..7644884 100644
--- a/main/bridge.c
+++ b/main/bridge.c
@@ -1551,7 +1551,7 @@
}
if (!res) {
- res = bridge_channel_internal_join(bridge_channel);
+ res = bridge_channel_internal_join(bridge_channel, NULL);
}
/* Cleanup all the data in the bridge channel after it leaves the bridge. */
@@ -1581,13 +1581,14 @@
/*! \brief Thread responsible for imparted bridged channels to be departed */
static void *bridge_channel_depart_thread(void *data)
{
- struct ast_bridge_channel *bridge_channel = data;
+ struct bridge_channel_internal_cond *cond = data;
+ struct ast_bridge_channel *bridge_channel = cond->bridge_channel;
if (bridge_channel->callid) {
ast_callid_threadassoc_add(bridge_channel->callid);
}
- bridge_channel_internal_join(bridge_channel);
+ bridge_channel_internal_join(bridge_channel, cond);
/*
* cleanup
@@ -1608,14 +1609,15 @@
/*! \brief Thread responsible for independent imparted bridged channels */
static void *bridge_channel_ind_thread(void *data)
{
- struct ast_bridge_channel *bridge_channel = data;
+ struct bridge_channel_internal_cond *cond = data;
+ struct ast_bridge_channel *bridge_channel = cond->bridge_channel;
struct ast_channel *chan;
if (bridge_channel->callid) {
ast_callid_threadassoc_add(bridge_channel->callid);
}
- bridge_channel_internal_join(bridge_channel);
+ bridge_channel_internal_join(bridge_channel, cond);
chan = bridge_channel->chan;
/* cleanup */
@@ -1699,13 +1701,27 @@
/* Actually create the thread that will handle the channel */
if (!res) {
+ struct bridge_channel_internal_cond cond = {
+ .done = 0,
+ .bridge_channel = bridge_channel
+ };
+ ast_mutex_init(&cond.lock);
+ ast_cond_init(&cond.cond, NULL);
+
if ((flags & AST_BRIDGE_IMPART_CHAN_MASK) == AST_BRIDGE_IMPART_CHAN_INDEPENDENT) {
res = ast_pthread_create_detached(&bridge_channel->thread, NULL,
- bridge_channel_ind_thread, bridge_channel);
+ bridge_channel_ind_thread, &cond);
} else {
res = ast_pthread_create(&bridge_channel->thread, NULL,
- bridge_channel_depart_thread, bridge_channel);
+ bridge_channel_depart_thread, &cond);
}
+
+ if (!res) {
+ bridge_channel_internal_wait(&cond);
+ }
+
+ ast_cond_destroy(&cond.cond);
+ ast_mutex_destroy(&cond.lock);
}
if (res) {
@@ -3955,6 +3971,15 @@
struct ast_channel *chan2, struct ast_bridge *bridge1, struct ast_bridge *bridge2,
struct ast_attended_transfer_message *transfer_msg)
{
+#define BRIDGE_LOCK_ONE_OR_BOTH(b1, b2) \
+ do { \
+ if (b2) { \
+ ast_bridge_lock_both(b1, b2); \
+ } else { \
+ ast_bridge_lock(b1); \
+ } \
+ } while (0)
+
static const char *dest = "_attended at transfer/m";
struct ast_channel *local_chan;
int cause;
@@ -3985,8 +4010,18 @@
return AST_BRIDGE_TRANSFER_FAIL;
}
+ /*
+ * Since bridges need to be unlocked before entering ast_bridge_impart and
+ * core_local may call into it then the bridges need to be unlocked here.
+ */
+ ast_bridge_unlock(bridge1);
+ if (bridge2) {
+ ast_bridge_unlock(bridge2);
+ }
+
if (ast_call(local_chan, dest, 0)) {
ast_hangup(local_chan);
+ BRIDGE_LOCK_ONE_OR_BOTH(bridge1, bridge2);
return AST_BRIDGE_TRANSFER_FAIL;
}
@@ -3996,8 +4031,10 @@
AST_BRIDGE_IMPART_CHAN_INDEPENDENT)) {
ast_hangup(local_chan);
ao2_cleanup(local_chan);
+ BRIDGE_LOCK_ONE_OR_BOTH(bridge1, bridge2);
return AST_BRIDGE_TRANSFER_FAIL;
}
+ BRIDGE_LOCK_ONE_OR_BOTH(bridge1, bridge2);
if (bridge2) {
RAII_VAR(struct ast_channel *, local_chan2, NULL, ao2_cleanup);
diff --git a/main/bridge_channel.c b/main/bridge_channel.c
index b7f0ba5..3ee04db 100644
--- a/main/bridge_channel.c
+++ b/main/bridge_channel.c
@@ -2560,7 +2560,27 @@
ao2_iterator_destroy(&iter);
}
-int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel)
+void bridge_channel_internal_wait(struct bridge_channel_internal_cond *cond)
+{
+ ast_mutex_lock(&cond->lock);
+ while (!cond->done) {
+ ast_cond_wait(&cond->cond, &cond->lock);
+ }
+ ast_mutex_unlock(&cond->lock);
+}
+
+void bridge_channel_internal_signal(struct bridge_channel_internal_cond *cond)
+{
+ if (cond) {
+ ast_mutex_lock(&cond->lock);
+ cond->done = 1;
+ ast_cond_signal(&cond->cond);
+ ast_mutex_unlock(&cond->lock);
+ }
+}
+
+int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel,
+ struct bridge_channel_internal_cond *cond)
{
int res = 0;
struct ast_bridge_features *channel_features;
@@ -2590,6 +2610,7 @@
bridge_channel->bridge->uniqueid,
bridge_channel,
ast_channel_name(bridge_channel->chan));
+ bridge_channel_internal_signal(cond);
return -1;
}
ast_channel_internal_bridge_set(bridge_channel->chan, bridge_channel->bridge);
@@ -2624,6 +2645,8 @@
}
bridge_reconfigured(bridge_channel->bridge, !bridge_channel->inhibit_colp);
+ bridge_channel_internal_signal(cond);
+
if (bridge_channel->state == BRIDGE_CHANNEL_STATE_WAIT) {
/*
* Indicate a source change since this channel is entering the
--
To view, visit https://gerrit.asterisk.org/839
To unsubscribe, visit https://gerrit.asterisk.org/settings
Gerrit-MessageType: merged
Gerrit-Change-Id: I08fe33a2560da924e676df55b181e46fca604577
Gerrit-PatchSet: 5
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Kevin Harwell <kharwell at digium.com>
Gerrit-Reviewer: Anonymous Coward #1000019
Gerrit-Reviewer: Kevin Harwell <kharwell at digium.com>
Gerrit-Reviewer: Mark Michelson <mmichelson at digium.com>
Gerrit-Reviewer: Richard Mudgett <rmudgett at digium.com>
More information about the asterisk-commits
mailing list