From ec9f917101371baaae34ca10ae952392c2c2343d Mon Sep 17 00:00:00 2001
From: Garrett D'Amore <garrett@damore.org>
Date: Tue, 13 Dec 2016 22:41:35 -0800
Subject: More comments, and detection of fork-reentrancy.  Much effort was
 spent trying to come to a fork-safe solution, but ultimately we gave up.

---
 src/platform/posix/posix_synch.h  | 18 +++++--------
 src/platform/posix/posix_thread.h | 56 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 61 insertions(+), 13 deletions(-)

(limited to 'src/platform')

diff --git a/src/platform/posix/posix_synch.h b/src/platform/posix/posix_synch.h
index 94058d32..d3e44411 100644
--- a/src/platform/posix/posix_synch.h
+++ b/src/platform/posix/posix_synch.h
@@ -85,11 +85,6 @@ nni_mutex_destroy(nni_mutex_t m)
 	if (pthread_mutex_destroy(&m->mx) != 0) {
 		nni_panic("pthread_mutex_destroy failed");
 	}
-	/*
-	 * If destroy fails for some reason, we can't really do
-	 * anything about it.  This would actually represent a programming
-	 * bug, and the right thing to do here would be to panic.
-	 */
 	nni_free(m, sizeof (*m));
 }
 
@@ -183,7 +178,6 @@ nni_cond_create(nni_cond_t *cvp, nni_mutex_t mx)
 		nni_free(c, sizeof (*c));
 		return (NNG_ENOMEM);
 	}
-
 	*cvp = c;
 	return (0);
 }
@@ -232,12 +226,12 @@ nni_cond_timedwait(nni_cond_t c, uint64_t usec)
 	ts.tv_sec = usec / 1000000;
 	ts.tv_nsec = (usec % 10000) * 1000;
 
-	if ((rv = pthread_cond_timedwait(&c->cv, c->mx, &ts)) != 0) {
-		if (rv == ETIMEDOUT) {
-			return (NNG_ETIMEDOUT);
-		} else {
-			nni_panic("pthread_cond_timedwait returned %d", rv);
-		}
+	rv = pthread_cond_timedwait(&c->cv, c->mx, &ts);
+
+	if (rv == ETIMEDOUT) {
+		return (NNG_ETIMEDOUT);
+	} else if (rv != 0) {
+		nni_panic("pthread_cond_timedwait returned %d", rv);
 	}
 	return (0);
 }
diff --git a/src/platform/posix/posix_thread.h b/src/platform/posix/posix_thread.h
index 239959f8..27ad888f 100644
--- a/src/platform/posix/posix_thread.h
+++ b/src/platform/posix/posix_thread.h
@@ -37,8 +37,23 @@
 
 struct nni_thread {
 	pthread_t	tid;
+	void *arg;
+	void (*func)(void *);
 };
 
+static pthread_mutex_t plat_lock = PTHREAD_MUTEX_INITIALIZER;
+static int plat_init = 0;
+static int plat_fork = 0;
+
+static void *
+thrfunc(void *arg)
+{
+	nni_thread_t thr = arg;
+
+	thr->func(thr->arg);
+	return (NULL);
+}
+
 int
 nni_thread_create(nni_thread_t *tp, void (*fn)(void *), void *arg)
 {
@@ -48,7 +63,10 @@ nni_thread_create(nni_thread_t *tp, void (*fn)(void *), void *arg)
 	if ((thr = nni_alloc(sizeof (*thr))) == NULL) {
 		return (NNG_ENOMEM);
 	}
-	if ((rv = pthread_create(&thr->tid, NULL, (void *)fn, arg)) != 0) {
+	thr->func = fn;
+	thr->arg = arg;
+
+	if ((rv = pthread_create(&thr->tid, thr, thrfunc, arg)) != 0) {
 		nni_free(thr, sizeof (*thr));
 		return (NNG_ENOMEM);
 	}
@@ -65,3 +83,39 @@ nni_thread_reap(nni_thread_t thr)
 	}
 	nni_free(thr, sizeof (*thr));
 }
+
+void
+atfork_child(void)
+{
+	plat_fork = 1;
+}
+
+int
+nni_platform_init(void)
+{
+	if (plat_fork) {
+		nni_panic("nng is fork-reentrant safe");
+	}
+	if (plat_init) {
+		return (0);	/* fast path */
+	}
+	pthread_mutex_lock(&plat_lock);
+	if (plat_init) {	/* check again under the lock to be sure */
+		pthread_mutex_unlock(&plat_lock);
+		return (0);
+	}
+	if (pthread_atfork(NULL, NULL, atfork_child) != 0) {
+		pthread_mutex_unlock(&plat_lock);
+		return (NNG_ENOMEM);
+	}
+	plat_init = 1;
+	pthread_mutex_unlock(&plat_lock);
+
+	return (0);
+}
+
+void
+nni_platform_fini(void)
+{
+	/* XXX: NOTHING *YET* */
+}
\ No newline at end of file
-- 
cgit v1.2.3-70-g09d2