Change signal handling to conform to POSIX specified semantics.

Before this change, a signal was delivered to each thread that
didn't have the signal masked.  Signals also improperly woke up
threads waiting on I/O.  With this change, signals are now
handled in the following way:

  o If a thread is waiting in a sigwait for the signal,
    then the thread is woken up.

  o If no threads are sigwait'ing on the signal and a
    thread is in a sigsuspend waiting for the signal,
    then the thread is woken up.

  o In the case that no threads are waiting or suspended
    on the signal, then the signal is delivered to the
    first thread we find that has the signal unmasked.

  o If no threads are waiting or suspended on the signal,
    and no threads have the signal unmasked, then the signal
    is added to the process wide pending signal set.  The
    signal will be delivered to the first thread that unmasks
    the signal.

If there is an installed signal handler, it is only invoked
if the chosen thread was not in a sigwait.

In the case that multiple threads are waiting or suspended
on a signal, or multiple threads have the signal unmasked,
we wake up/deliver the signal to the first thread we find.
The above rules still apply.

Reported by:	Scott Hess <scott@avantgo.com>
Reviewed by:	jb, jasone

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/libpthread/thread/thr_fork.c b/lib/libpthread/thread/thr_fork.c
index 155416e2ec3a..b8d72dc00da2 100644
--- a/lib/libpthread/thread/thr_fork.c
+++ b/lib/libpthread/thread/thr_fork.c
@@ -164,6 +164,9 @@ fork(void)
 				}
 			}
 
+			/* Treat the current thread as the initial thread: */
+			_thread_initial = _thread_run;
+
 			/* Re-init the dead thread list: */
 			TAILQ_INIT(&_dead_list);