Don't needlessly poll file descriptors when there are no

file descriptors needing to be polled (Doh!).  Reported
by Dan Nelson <dnelson@emsphone.com>.

Don't install and start the scheduling timer until the
first thread is created.  This prevents the overhead of
having a periodic scheduling signal in a single threaded
program.  Reported by Dan Nelson <dnelson@emsphone.com>.

Allow builtin longjmps out of application installed
signal handlers without the need perform any post-handler
cleanup:

  o Change signal handling to save the threads interrupted
    context on the stack.  The threads current context is
    now always stored in the same place (in the pthread).
    If and when a signal handler returns, the interrupted
    context is copied back to the storage area in the pthread.

  o Before calling invoking a signal handler for a thread,
    back the thread out of any internal waiting queues
    (mutex, CV, join, etc) to which it belongs.

Rework uthread_info.c a bit to make it easier to change
the format of a thread dump.

Use an alternal signal stack for the thread library's
signal handler.  This allows us to fiddle with the main
threads stack without fear of it being in use.

Reviewed by:	jasone

1 files changed, 14 insertions, 21 deletions

diff --git a/lib/libkse/thread/thr_exit.c b/lib/libkse/thread/thr_exit.c
index 7fbeb65..aef12fe 100644
--- a/lib/libkse/thread/thr_exit.c
+++ b/lib/libkse/thread/thr_exit.c
@@ -141,7 +141,7 @@ _thread_exit_cleanup(void)
 void
 pthread_exit(void *status)
 {
-	int	frame;
+	pthread_t pthread;
 
 	/* Check if this thread is already in the process of exiting: */
 	if ((_thread_run->flags & PTHREAD_EXITING) != 0) {
@@ -159,7 +159,6 @@ pthread_exit(void *status)
 	while (_thread_run->cleanup != NULL) {
 		pthread_cleanup_pop(1);
 	}
-
 	if (_thread_run->attr.cleanup_attr != NULL) {
 		_thread_run->attr.cleanup_attr(_thread_run->attr.arg_attr);
 	}
@@ -175,25 +174,6 @@ pthread_exit(void *status)
 		_thread_run->poll_data.fds = NULL;
 	}
 
-	if ((frame = _thread_run->sigframe_count) == 0)
-		_thread_exit_finish();
-	else {
-		/*
-		 * Jump back and unwind the signal frames to gracefully
-		 * cleanup.
-		 */
-		___longjmp(*_thread_run->sigframes[frame]->sig_jb, 1);
-	}
-
-	/* This point should not be reached. */
-	PANIC("Dead thread has resumed");
-}
-
-void
-_thread_exit_finish(void)
-{
-	pthread_t	pthread;
-
 	/*
 	 * Lock the garbage collector mutex to ensure that the garbage
 	 * collector is not using the dead thread list.
@@ -233,6 +213,16 @@ _thread_exit_finish(void)
 		 * detach this thread:
 		 */
 		PTHREAD_NEW_STATE(pthread, PS_RUNNING);
+
+		/*
+		 * Set the return value for the woken thread:
+		 */
+		if ((_thread_run->attr.flags & PTHREAD_DETACHED) != 0)
+			pthread->error = ESRCH;
+		else {
+			pthread->ret = _thread_run->ret;
+			pthread->error = 0;
+		}
 	}
 
 	/* Remove this thread from the thread list: */
@@ -240,5 +230,8 @@ _thread_exit_finish(void)
 
 	/* This thread will never be re-scheduled. */
 	_thread_kern_sched_state(PS_DEAD, __FILE__, __LINE__);
+
+	/* This point should not be reached. */
+	PANIC("Dead thread has resumed");
 }
 #endif