diff options
Diffstat (limited to 'lib/libthr')
| -rw-r--r-- | lib/libthr/thread/thr_cancel.c | 21 | ||||
| -rw-r--r-- | lib/libthr/thread/thr_private.h | 1 | ||||
| -rw-r--r-- | lib/libthr/thread/thr_spinlock.c | 10 |
3 files changed, 28 insertions, 4 deletions
diff --git a/lib/libthr/thread/thr_cancel.c b/lib/libthr/thread/thr_cancel.c index ec2bfb6..7e1bace 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); diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h index 3668a0e..db2bab2 100644 --- a/lib/libthr/thread/thr_private.h +++ b/lib/libthr/thread/thr_private.h @@ -737,6 +737,7 @@ int _pthread_mutexattr_settype(pthread_mutexattr_t *, int); int _pthread_once(pthread_once_t *, void (*) (void)); pthread_t _pthread_self(void); int _pthread_setspecific(pthread_key_t, const void *); +int _spintrylock(spinlock_t *); inline void _spinlock_pthread(pthread_t, spinlock_t *); inline void _spinunlock_pthread(pthread_t, spinlock_t *); void _thread_exit(char *, int, char *); diff --git a/lib/libthr/thread/thr_spinlock.c b/lib/libthr/thread/thr_spinlock.c index ff9b9e0..0f9cb6b 100644 --- a/lib/libthr/thread/thr_spinlock.c +++ b/lib/libthr/thread/thr_spinlock.c @@ -69,6 +69,16 @@ _spinlock(spinlock_t *lck) _spinlock_pthread(curthread, lck); } +int +_spintrylock(spinlock_t *lck) +{ + int error; + error = umtx_trylock((struct umtx *)lck, curthread->thr_id); + if (error != 0 && error != EBUSY) + abort(); + return (error); +} + inline void _spinlock_pthread(pthread_t pthread, spinlock_t *lck) { |
