6209 libc mutexes break kernel writers hearts

Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Approved by: Dan McDonald <danmcd@omniti.com>

4 files changed, 58 insertions, 1 deletions

diff --git a/usr/src/lib/libc/inc/thr_uberdata.h b/usr/src/lib/libc/inc/thr_uberdata.h
index de0d4a6b05..4815d11486 100644
--- a/usr/src/lib/libc/inc/thr_uberdata.h
+++ b/usr/src/lib/libc/inc/thr_uberdata.h
@@ -23,7 +23,7 @@
  * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 /*
- * Copyright (c) 2014, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2015, Joyent, Inc.
  */
 
 #ifndef _THR_UBERDATA_H
@@ -1229,6 +1229,8 @@ extern	void	getgregs(ulwp_t *, gregset_t);
 extern	void	setgregs(ulwp_t *, gregset_t);
 extern	void	thr_panic(const char *);
 #pragma rarely_called(thr_panic)
+extern	void	mutex_panic(mutex_t *, const char *);
+#pragma rarely_called(mutex_panic)
 extern	ulwp_t	*find_lwp(thread_t);
 extern	void	finish_init(void);
 extern	void	update_sched(ulwp_t *);
diff --git a/usr/src/lib/libc/port/mapfile-vers b/usr/src/lib/libc/port/mapfile-vers
index c4571ef2f1..c6967141b6 100644
--- a/usr/src/lib/libc/port/mapfile-vers
+++ b/usr/src/lib/libc/port/mapfile-vers
@@ -2915,6 +2915,8 @@ $endif
 	msgctl64;
 	__multi_innetgr;
 	_mutex_destroy		{ FLAGS = NODYNSORT };
+	mutex_enter;
+	mutex_exit;
 	mutex_held;
 	_mutex_init		{ FLAGS = NODYNSORT };
 	_mutex_unlock		{ FLAGS = NODYNSORT };
diff --git a/usr/src/lib/libc/port/threads/assfail.c b/usr/src/lib/libc/port/threads/assfail.c
index 8aebefbe4a..b40e6dc029 100644
--- a/usr/src/lib/libc/port/threads/assfail.c
+++ b/usr/src/lib/libc/port/threads/assfail.c
@@ -25,6 +25,7 @@
  */
 /*
  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
+ * Copyright 2015 Joyent, Inc.
  */
 
 #include "lint.h"
@@ -36,6 +37,8 @@ ulwp_t *panic_thread;
 static mutex_t assert_lock = DEFAULTMUTEX;
 static ulwp_t *assert_thread = NULL;
 
+mutex_t *panic_mutex = NULL;
+
 /*
  * Called from __assert() to set panicstr and panic_thread.
  */
@@ -129,6 +132,13 @@ aio_panic(const char *why)
 	common_panic("*** libc aio system failure: ", why);
 }
 
+void
+mutex_panic(mutex_t *mp, const char *why)
+{
+	panic_mutex = mp;
+	common_panic("*** libc mutex system failure: ", why);
+}
+
 /*
  * Utility function for converting a long integer to a string, avoiding stdio.
  * 'base' must be one of 10 or 16
diff --git a/usr/src/lib/libc/port/threads/synch.c b/usr/src/lib/libc/port/threads/synch.c
index a7c4aed9ef..b4efb58d17 100644
--- a/usr/src/lib/libc/port/threads/synch.c
+++ b/usr/src/lib/libc/port/threads/synch.c
@@ -22,6 +22,7 @@
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright 2015, Joyent, Inc.
  */
 
 #include "lint.h"
@@ -2314,6 +2315,29 @@ mutex_lock(mutex_t *mp)
 	return (mutex_lock_impl(mp, NULL));
 }
 
+void
+mutex_enter(mutex_t *mp)
+{
+	int ret;
+	int attr = mp->mutex_type & ALL_ATTRIBUTES;
+
+	/*
+	 * Require LOCK_ERRORCHECK, accept LOCK_RECURSIVE.
+	 */
+	if (attr != LOCK_ERRORCHECK &&
+	    attr != (LOCK_ERRORCHECK | LOCK_RECURSIVE)) {
+		mutex_panic(mp, "mutex_enter: bad mutex type");
+	}
+	ret = mutex_lock(mp);
+	if (ret == EDEADLK) {
+		mutex_panic(mp, "recursive mutex_enter");
+	} else if (ret == EAGAIN) {
+		mutex_panic(mp, "excessive recursive mutex_enter");
+	} else if (ret != 0) {
+		mutex_panic(mp, "unknown mutex_enter failure");
+	}
+}
+
 int
 pthread_mutex_timedlock(pthread_mutex_t *_RESTRICT_KYWD mp,
 	const struct timespec *_RESTRICT_KYWD abstime)
@@ -2573,6 +2597,25 @@ slow_unlock:
 	return (mutex_unlock_internal(mp, 0));
 }
 
+void
+mutex_exit(mutex_t *mp)
+{
+	int ret;
+	int attr = mp->mutex_type & ALL_ATTRIBUTES;
+
+	if (attr != LOCK_ERRORCHECK &&
+	    attr != (LOCK_ERRORCHECK | LOCK_RECURSIVE)) {
+		mutex_panic(mp, "mutex_exit: bad mutex type");
+	}
+	ret = mutex_unlock(mp);
+	if (ret == EPERM) {
+		mutex_panic(mp, "mutex_exit: not owner");
+	} else if (ret != 0) {
+		mutex_panic(mp, "unknown mutex_exit failure");
+	}
+
+}
+
 /*
  * Internally to the library, almost all mutex lock/unlock actions
  * go through these lmutex_ functions, to protect critical regions.