diff options
| author | Frederic LE FOLL <frederic.lefoll@c-s.fr> | 2017-06-08 19:28:12 +0200 |
|---|---|---|
| committer | George Joseph <gjoseph@digium.com> | 2017-06-16 13:26:22 -0500 |
| commit | 0ad95bc8a048e165148c68c5bdec5555b25218a9 (patch) | |
| tree | 91ab4d4ee1318e758eeb8b75af2f69ee54a0455c /main/pbx_app.c | |
| parent | 0405185357d4d857af7375fa495c6893f943e249 (diff) | |
Core/PBX: Deadlock between dialplan execution and application unregistration.
Not easy to reproduce, but we have noticed deadlocks when unloading a module
while dialplan is handling a request.
The deadlock is between :
1) Dialplan execution: pbx_extension_helper() first taking conlock,
then pbx_findapp() [when called] asking for lock on apps list.
2) Application unregistration: ast_unregister_application() first taking lock
on apps list, then unreference_cached_app() [when called] asking for conlock.
As a protection, I suggest to modify ast_unregister_application(), so that it
anticipates the need of conlock, before taking the lock on apps list.
The side effect is a longer unavailability of conlock when unregistering an
application.
ASTERISK-27041
Change-Id: I0db0f1eb320da6a5758cce3a47d765be1face8e2
Diffstat (limited to 'main/pbx_app.c')
| -rw-r--r-- | main/pbx_app.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/main/pbx_app.c b/main/pbx_app.c index e0609db70..ec6bc7589 100644 --- a/main/pbx_app.c +++ b/main/pbx_app.c @@ -394,6 +394,11 @@ int ast_unregister_application(const char *app) struct ast_app *cur; int cmp; + /* Anticipate need for conlock in unreference_cached_app(), in order to avoid + * possible deadlock with pbx_extension_helper()/pbx_findapp() + */ + ast_rdlock_contexts(); + AST_RWLIST_WRLOCK(&apps); AST_RWLIST_TRAVERSE_SAFE_BEGIN(&apps, cur, list) { cmp = strcasecmp(app, cur->name); @@ -416,6 +421,8 @@ int ast_unregister_application(const char *app) AST_RWLIST_TRAVERSE_SAFE_END; AST_RWLIST_UNLOCK(&apps); + ast_unlock_contexts(); + return cur ? 0 : -1; } |