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, 28 deletions

diff --git a/lib/libpthread/thread/thr_kill.c b/lib/libpthread/thread/thr_kill.c
index eb2c6b7..f6e684b 100644
--- a/lib/libpthread/thread/thr_kill.c
+++ b/lib/libpthread/thread/thr_kill.c
@@ -39,40 +39,19 @@
 int
 pthread_kill(pthread_t pthread, int sig)
 {
-	int             rval = 0;
-	int             status;
-	pthread_t	p_pthread;
+	int ret;
 
 	/* Check for invalid signal numbers: */
 	if (sig < 0 || sig >= NSIG)
 		/* Invalid signal: */
-		rval = EINVAL;
-	else {
-		/* Assume that the search will succeed: */
-		rval = 0;
+		ret = EINVAL;
 
-		/* Block signals: */
-		_thread_kern_sig_block(&status);
-
-		/* Search for the thread: */
-		p_pthread = _thread_link_list;
-		while (p_pthread != NULL && p_pthread != pthread) {
-			p_pthread = p_pthread->nxt;
-		}
-
-		/* Check if the thread was not found: */
-		if (p_pthread == NULL)
-			/* Can't find the thread: */
-			rval = ESRCH;
-		else
-			/* Increment the pending signal count: */
-			p_pthread->sigpend[sig] += 1;
-
-		/* Unblock signals: */
-		_thread_kern_sig_unblock(status);
-	}
+	/* Find the thread in the list of active threads: */
+	else if ((ret = _find_thread(pthread)) == 0)
+		/* Increment the pending signal count: */
+		sigaddset(&pthread->sigpend,sig);
 
 	/* Return the completion status: */
-	return (rval);
+	return (ret);
 }
 #endif