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Fix deadlock handling subscribe req during res_parking reload 

Split destroy_hint method to separate hint removal and extension hint
state changed callback, the latter now called via stasis.
This avoids deadlock between res_parking reload that is removing the
parking lot and the related hint and subscribe requests coming for the
same parking lot.

ASTERISK-28173

Change-Id: I5b03c3455b3b12b6f83cea4cc34f4b4b20444f7e
This commit is contained in:
Giuseppe Sucameli 2018-11-20 01:44:23 +01:00 committed by George Joseph
parent 3d54ef5978
commit 419db481d1
1 changed files with 55 additions and 30 deletions
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85
main/pbx.c
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@ -346,6 +346,7 @@ struct ast_hint {
};
STASIS_MESSAGE_TYPE_DEFN_LOCAL(hint_change_message_type);
STASIS_MESSAGE_TYPE_DEFN_LOCAL(hint_remove_message_type);
#define HINTDEVICE_DATA_LENGTH 16
AST_THREADSTORAGE(hintdevice_data);
@ -3570,6 +3571,30 @@ static void device_state_cb(void *unused, struct stasis_subscription *sub, struc
return;
}
if (hint_remove_message_type() == stasis_message_type(msg)) {
/* The extension has already been destroyed */
struct ast_state_cb *state_cb;
struct ao2_iterator cb_iter;
struct ast_hint *hint = stasis_message_data(msg);
ao2_lock(hint);
hint->laststate = AST_EXTENSION_DEACTIVATED;
ao2_unlock(hint);
cb_iter = ao2_iterator_init(hint->callbacks, 0);
for (; (state_cb = ao2_iterator_next(&cb_iter)); ao2_ref(state_cb, -1)) {
execute_state_callback(state_cb->change_cb,
hint->context_name,
hint->exten_name,
state_cb->data,
AST_HINT_UPDATE_DEVICE,
hint,
NULL);
}
ao2_iterator_destroy(&cb_iter);
return;
}
if (ast_device_state_message_type() != stasis_message_type(msg)) {
return;
}
@ -3855,34 +3880,7 @@ static void destroy_hint(void *obj)
struct ast_hint *hint = obj;
int i;
if (hint->callbacks) {
struct ast_state_cb *state_cb;
const char *context_name;
const char *exten_name;
if (hint->exten) {
context_name = ast_get_context_name(ast_get_extension_context(hint->exten));
exten_name = ast_get_extension_name(hint->exten);
hint->exten = NULL;
} else {
/* The extension has already been destroyed */
context_name = hint->context_name;
exten_name = hint->exten_name;
}
hint->laststate = AST_EXTENSION_DEACTIVATED;
while ((state_cb = ao2_callback(hint->callbacks, OBJ_UNLINK, NULL, NULL))) {
/* Notify with -1 and remove all callbacks */
execute_state_callback(state_cb->change_cb,
context_name,
exten_name,
state_cb->data,
AST_HINT_UPDATE_DEVICE,
hint,
NULL);
ao2_ref(state_cb, -1);
}
ao2_ref(hint->callbacks, -1);
}
ao2_cleanup(hint->callbacks);
for (i = 0; i < AST_VECTOR_SIZE(&hint->devices); i++) {
char *device = AST_VECTOR_GET(&hint->devices, i);
@ -3893,6 +3891,27 @@ static void destroy_hint(void *obj)
ast_free(hint->last_presence_message);
}
/*! \brief Publish a hint removed event */
static int publish_hint_remove(struct ast_hint *hint)
{
struct stasis_message *message;
if (!hint_remove_message_type()) {
return -1;
}
if (!(message = stasis_message_create(hint_remove_message_type(), hint))) {
ao2_ref(hint, -1);
return -1;
}
stasis_publish(ast_device_state_topic_all(), message);
ao2_ref(message, -1);
return 0;
}
/*! \brief Remove hint from extension */
static int ast_remove_hint(struct ast_exten *e)
{
@ -3923,6 +3942,8 @@ static int ast_remove_hint(struct ast_exten *e)
hint->exten = NULL;
ao2_unlock(hint);
publish_hint_remove(hint);
ao2_ref(hint, -1);
return 0;
@ -4029,8 +4050,7 @@ static int publish_hint_change(struct ast_hint *hint, struct ast_exten *ne)
return -1;
}
/* The message is going to be published to two topics so the hint needs two refs */
if (!(message = stasis_message_create(hint_change_message_type(), ao2_bump(hint)))) {
if (!(message = stasis_message_create(hint_change_message_type(), hint))) {
ao2_ref(hint, -1);
return -1;
}
@ -8418,6 +8438,7 @@ int load_pbx(void)
}
stasis_subscription_accept_message_type(device_state_sub, ast_device_state_message_type());
stasis_subscription_accept_message_type(device_state_sub, hint_change_message_type());
stasis_subscription_accept_message_type(device_state_sub, hint_remove_message_type());
stasis_subscription_set_filter(device_state_sub, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);
if (!(presence_state_sub = stasis_subscribe(ast_presence_state_topic_all(), presence_state_cb, NULL))) {
@ -8841,6 +8862,7 @@ static int statecbs_cmp(void *obj, void *arg, int flags)
static void pbx_shutdown(void)
{
STASIS_MESSAGE_TYPE_CLEANUP(hint_change_message_type);
STASIS_MESSAGE_TYPE_CLEANUP(hint_remove_message_type);
if (hints) {
ao2_container_unregister("hints");
@ -8938,6 +8960,9 @@ int ast_pbx_init(void)
if (STASIS_MESSAGE_TYPE_INIT(hint_change_message_type) != 0) {
return -1;
}
if (STASIS_MESSAGE_TYPE_INIT(hint_remove_message_type) != 0) {
return -1;
}
return (hints && hintdevices && autohints && statecbs) ? 0 : -1;
}