Change signal model to match POSIX (i.e. one set of signal handlers

for the process, not a separate set for each thread). By default, the
process now only has signal handlers installed for SIGVTALRM, SIGINFO
and SIGCHLD. The thread kernel signal handler is installed for other
signals on demand. This means that SIG_IGN and SIG_DFL processing is now
left to the kernel, not the thread kernel.

Change the signal dispatch to no longer use a signal thread, and
call the signal handler using the stack of the thread that has the
signal pending.

Change the atomic lock method to use test-and-set asm code with
a yield if blocked. This introduces separate locks for each type
of object instead of blocking signals to prevent a context
switch. It was this blocking of signals that caused the performance
degradation the people have noted.

This is a *big* change!

1 files changed, 7 insertions, 7 deletions

diff --git a/lib/libkse/thread/thr_fork.c b/lib/libkse/thread/thr_fork.c
index 29d6090..25d6703 100644
--- a/lib/libkse/thread/thr_fork.c
+++ b/lib/libkse/thread/thr_fork.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
+ * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -47,8 +47,8 @@ fork(void)
 	pthread_t	pthread;
 	pthread_t	pthread_next;
 
-	/* Block signals to avoid being interrupted at a bad time: */
-	_thread_kern_sig_block(&status);
+	/* Lock the thread list: */
+	_lock_thread_list();
 
 	/* Fork a new process: */
 	if ((ret = _thread_sys_fork()) <= 0) {
@@ -59,12 +59,12 @@ fork(void)
 		_thread_sys_close(_thread_kern_pipe[1]);
 
 		/* Reset signals pending for the running thread: */
-		memset(_thread_run->sigpend, 0, sizeof(_thread_run->sigpend));
+		_thread_run->sigpend = 0;
 
 		/*
 		 * Create a pipe that is written to by the signal handler to
 		 * prevent signals being missed in calls to
-		 * _thread_sys_select: 
+		 * _select: 
 		 */
 		if (_thread_sys_pipe(_thread_kern_pipe) != 0) {
 			/* Cannot create pipe, so abort: */
@@ -122,8 +122,8 @@ fork(void)
 		}
 	}
 
-	/* Unblock signals: */
-	_thread_kern_sig_unblock(status);
+	/* Unock the thread list: */
+	_unlock_thread_list();
 
 	/* Return the process ID: */
 	return (ret);