[src/trunk]: src/lib/libpthread Make pthread_join() accomodate spurious wakeu...

[nathanw <nathanw%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3047c6558547
branches:  trunk
changeset: 542268:3047c6558547
user:      nathanw <nathanw%NetBSD.org@localhost>
date:      Sat Jan 25 00:37:01 2003 +0000

description:
Make pthread_join() accomodate spurious wakeups from pthread__block().

diffstat:

 lib/libpthread/pthread.c |  26 ++++++++++++++++----------
 1 files changed, 16 insertions(+), 10 deletions(-)

diffs (54 lines):

diff -r 9f0ab77f0599 -r 3047c6558547 lib/libpthread/pthread.c
--- a/lib/libpthread/pthread.c  Sat Jan 25 00:17:30 2003 +0000
+++ b/lib/libpthread/pthread.c  Sat Jan 25 00:37:01 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pthread.c,v 1.5 2003/01/19 21:58:24 thorpej Exp $      */
+/*     $NetBSD: pthread.c,v 1.6 2003/01/25 00:37:01 nathanw Exp $      */
 
 /*-
  * Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -415,6 +415,7 @@
 pthread_join(pthread_t thread, void **valptr)
 {
        pthread_t self;
+       int num;
 
        self = pthread__self();
        SDPRINTF(("(pthread_join %p) Joining %p.\n", self, thread));
@@ -435,8 +436,20 @@
                return EINVAL;
        }
 
-       if ((thread->pt_state != PT_STATE_ZOMBIE) &&
-           (thread->pt_state != PT_STATE_DEAD)) {
+       num = thread->pt_num;
+       while (thread->pt_state != PT_STATE_ZOMBIE) {
+               if ((thread->pt_state == PT_STATE_DEAD) ||
+                   (thread->pt_flags & PT_FLAG_DETACHED) ||
+                   (thread->pt_num != num)) {
+                       /*
+                        * Another thread beat us to the join, or called
+                        * pthread_detach(). If num didn't match, the
+                        * thread died and was recycled before we got
+                        * another chance to run.
+                        */
+                       pthread_spinunlock(self, &thread->pt_join_lock);
+                       return ESRCH;
+               }
                /*
                 * "I'm not dead yet!"
                 * "You will be soon enough."
@@ -458,13 +471,6 @@
                pthread_spinlock(self, &thread->pt_join_lock);
        }
 
-       if ((thread->pt_state == PT_STATE_DEAD) ||
-           (thread->pt_flags & PT_FLAG_DETACHED)) {
-               /* Someone beat us to the join, or called pthread_detach(). */
-               pthread_spinunlock(self, &thread->pt_join_lock);
-               return ESRCH;
-       }
-
        /* All ours. */
        thread->pt_state = PT_STATE_DEAD;
        pthread_spinunlock(self, &thread->pt_join_lock);