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, 23 insertions, 49 deletions

diff --git a/lib/libpthread/thread/thr_join.c b/lib/libpthread/thread/thr_join.c
index 9e86a01..83b0c2a 100644
--- a/lib/libpthread/thread/thr_join.c
+++ b/lib/libpthread/thread/thr_join.c
@@ -38,9 +38,8 @@
 int
 pthread_join(pthread_t pthread, void **thread_return)
 {
-	int             rval = 0;
-	int             status;
-	pthread_t	pthread1;
+	int ret = 0;
+	pthread_t pthread1 = NULL;
 
 	/* Check if the caller has specified an invalid thread: */
 	if (pthread == NULL || pthread->magic != PTHREAD_MAGIC)
@@ -52,38 +51,23 @@ pthread_join(pthread_t pthread, void **thread_return)
 		/* Avoid a deadlock condition: */
 		return(EDEADLK);
 
-	/* Block signals: */
-	_thread_kern_sig_block(&status);
+	/*
+	 * Find the thread in the list of active threads or in the
+	 * list of dead threads:
+	 */
+	if (_find_thread(pthread) == 0 ||
+	    _find_dead_thread(pthread) == 0)
+		pthread1  = pthread;
 
-	/* Point to the first thread in the list: */
-	pthread1 = _thread_link_list;
-
-	/* Search for the thread to join to: */
-	while (pthread1 != NULL && pthread1 != pthread) {
-		/* Point to the next thread: */
-		pthread1 = pthread1->nxt;
-	}
-
-	if (pthread1 == NULL) {
-		/* Point to the first thread in the dead thread list: */
-		pthread1 = _thread_dead;
-
-		/* Search for the thread to join to: */
-		while (pthread1 != NULL && pthread1 != pthread) {
-			/* Point to the next thread: */
-			pthread1 = pthread1->nxt;
-		}
-	}
-
-	if (pthread1 == NULL) {
+	if (pthread1 == NULL)
 		/* Return an error: */
-		rval = ESRCH;
+		ret = ESRCH;
 
 	/* Check if this thread has been detached: */
-	} else if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) {
+	else if ((pthread->attr.flags & PTHREAD_DETACHED) != 0)
 		/* Return an error: */
-		rval = ESRCH;
-	}
+		ret = ESRCH;
+
 	/* Check if the thread is not dead: */
 	else if (pthread->state != PS_DEAD) {
 		/* Add the running thread to the join queue: */
@@ -92,32 +76,22 @@ pthread_join(pthread_t pthread, void **thread_return)
 		/* Schedule the next thread: */
 		_thread_kern_sched_state(PS_JOIN, __FILE__, __LINE__);
 
-		/* Block signals again: */
-		_thread_kern_sig_block(NULL);
-
 		/* Check if the thread is not detached: */
-		if ((pthread->attr.flags & PTHREAD_DETACHED) == 0) {
+		if ((pthread->attr.flags & PTHREAD_DETACHED) == 0)
 			/* Check if the return value is required: */
-			if (thread_return) {
+			if (thread_return)
 				/* Return the thread's return value: */
 				*thread_return = pthread->ret;
-			}
-		} else {
+		else
 			/* Return an error: */
-			rval = ESRCH;
-		}
-	} else {
-		/* Check if the return value is required: */
-		if (thread_return != NULL) {
-			/* Return the thread's return value: */
-			*thread_return = pthread->ret;
-		}
-	}
+			ret = ESRCH;
 
-	/* Unblock signals: */
-	_thread_kern_sig_unblock(status);
+	/* Check if the return value is required: */
+	} else if (thread_return != NULL)
+		/* Return the thread's return value: */
+		*thread_return = pthread->ret;
 
 	/* Return the completion status: */
-	return (rval);
+	return (ret);
 }
 #endif