diff options
Diffstat (limited to 'lib/libthr/thread/thr_cancel.c')
| -rw-r--r-- | lib/libthr/thread/thr_cancel.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/lib/libthr/thread/thr_cancel.c b/lib/libthr/thread/thr_cancel.c index ec2bfb674c45..7e1bace02cf3 100644 --- a/lib/libthr/thread/thr_cancel.c +++ b/lib/libthr/thread/thr_cancel.c @@ -21,7 +21,16 @@ int _pthread_cancel(pthread_t pthread) { int ret; + pthread_t joined; + /* + * When canceling a thread that has joined another thread, this + * routine breaks the normal lock order of locking first the + * joined and then the joiner. Therefore, it is necessary that + * if it can't obtain the second lock, that it release the first + * one and restart from the top. + */ +retry: if ((ret = _find_thread(pthread)) != 0) /* The thread is not on the list of active threads */ goto out; @@ -70,10 +79,14 @@ _pthread_cancel(pthread_t pthread) /* * Disconnect the thread from the joinee: */ - if (pthread->join_status.thread != NULL) { - pthread->join_status.thread->joiner - = NULL; - pthread->join_status.thread = NULL; + if ((joined = pthread->join_status.thread) != NULL) { + if (_spintrylock(&joined->lock) == EBUSY) { + _thread_critical_exit(pthread); + goto retry; + } + pthread->join_status.thread->joiner = NULL; + _spinunlock(&joined->lock); + joined = pthread->join_status.thread = NULL; } pthread->cancelflags |= PTHREAD_CANCELLING; PTHREAD_NEW_STATE(pthread, PS_RUNNING); |