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Merged revisions 16742 via svnmerge from

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https://origsvn.digium.com/svn/asterisk/branches/1.2

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r16742 | kpfleming | 2006-03-31 12:24:22 -0600 (Fri, 31 Mar 2006) | 2 lines

ensure that hint watchers (subscribers) cannot be added or removed while the dialplan is being modified

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@16743 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Kevin P. Fleming
2006-03-31 18:28:52 +00:00
parent a4bbb3ff90
commit 2de95d53bc
1 changed files with 21 additions and 6 deletions
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27
pbx.c
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@@ -470,6 +470,12 @@ struct ast_switch *switches = NULL;
AST_MUTEX_DEFINE_STATIC(switchlock); /*!< Lock for switches */
static int stateid = 1;
/* WARNING:
When holding this list's lock, do _not_ do anything that will cause conlock
to be taken, unless you _already_ hold it. The ast_merge_contexts_and_delete
function will take the locks in conlock/hints order, so any other
paths that require both locks must also take them in that order.
*/
static AST_LIST_HEAD_STATIC(hints, ast_hint);
struct ast_state_cb *statecbs = NULL;
@@ -3508,9 +3514,20 @@ void ast_merge_contexts_and_delete(struct ast_context **extcontexts, const char
int length;
struct ast_state_cb *thiscb, *prevcb;
/* preserve all watchers for hints associated with this registrar */
AST_LIST_HEAD_INIT(&store);
/* it is very important that this function hold the hint list lock _and_ the conlock
during its operation; not only do we need to ensure that the list of contexts
and extensions does not change, but also that no hint callbacks (watchers) are
added or removed during the merge/delete process
in addition, the locks _must_ be taken in this order, because there are already
other code paths that use this order
*/
ast_mutex_lock(&conlock);
AST_LIST_LOCK(&hints);
/* preserve all watchers for hints associated with this registrar */
AST_LIST_TRAVERSE(&hints, hint, list) {
if (hint->callbacks && !strcmp(registrar, hint->exten->parent->registrar)) {
length = strlen(hint->exten->exten) + strlen(hint->exten->parent->name) + 2 + sizeof(*this);
@@ -3526,10 +3543,8 @@ void ast_merge_contexts_and_delete(struct ast_context **extcontexts, const char
AST_LIST_INSERT_HEAD(&store, this, list);
}
}
AST_LIST_UNLOCK(&hints);
tmp = *extcontexts;
ast_mutex_lock(&conlock);
if (registrar) {
__ast_context_destroy(NULL,registrar);
while (tmp) {
@@ -3549,7 +3564,6 @@ void ast_merge_contexts_and_delete(struct ast_context **extcontexts, const char
*extcontexts = NULL;
} else
ast_log(LOG_WARNING, "Requested contexts didn't get merged\n");
ast_mutex_unlock(&conlock);
/* restore the watchers for hints that can be found; notify those that
cannot be restored
@@ -3557,7 +3571,6 @@ void ast_merge_contexts_and_delete(struct ast_context **extcontexts, const char
while ((this = AST_LIST_REMOVE_HEAD(&store, list))) {
exten = ast_hint_extension(NULL, this->context, this->exten);
/* Find the hint in the list of hints */
AST_LIST_LOCK(&hints);
AST_LIST_TRAVERSE(&hints, hint, list) {
if (hint->exten == exten)
break;
@@ -3580,10 +3593,12 @@ void ast_merge_contexts_and_delete(struct ast_context **extcontexts, const char
hint->callbacks = this->callbacks;
hint->laststate = this->laststate;
}
AST_LIST_UNLOCK(&hints);
free(this);
}
AST_LIST_UNLOCK(&hints);
ast_mutex_unlock(&conlock);
return;
}