From owner-svn-src-head@FreeBSD.ORG  Sun Sep 19 05:19:47 2010
Return-Path: <owner-svn-src-head@FreeBSD.ORG>
Delivered-To: svn-src-head@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id E6486106566B;
	Sun, 19 Sep 2010 05:19:47 +0000 (UTC)
	(envelope-from davidxu@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id D62CB8FC0A;
	Sun, 19 Sep 2010 05:19:47 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id o8J5Jl4I090111;
	Sun, 19 Sep 2010 05:19:47 GMT (envelope-from davidxu@svn.freebsd.org)
Received: (from davidxu@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id o8J5JlOx090109;
	Sun, 19 Sep 2010 05:19:47 GMT (envelope-from davidxu@svn.freebsd.org)
Message-Id: <201009190519.o8J5JlOx090109@svn.freebsd.org>
From: David Xu <davidxu@FreeBSD.org>
Date: Sun, 19 Sep 2010 05:19:47 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r212837 - head/lib/libthr/thread
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
	<svn-src-head.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
	<mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
	<mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 19 Sep 2010 05:19:48 -0000

Author: davidxu
Date: Sun Sep 19 05:19:47 2010
New Revision: 212837
URL: http://svn.freebsd.org/changeset/base/212837

Log:
  Fix a race condition when finding stack unwinding functions.

Modified:
  head/lib/libthr/thread/thr_exit.c

Modified: head/lib/libthr/thread/thr_exit.c
==============================================================================
--- head/lib/libthr/thread/thr_exit.c	Sun Sep 19 02:07:30 2010	(r212836)
+++ head/lib/libthr/thread/thr_exit.c	Sun Sep 19 05:19:47 2010	(r212837)
@@ -70,18 +70,31 @@ static void
 thread_uw_init(void)
 {
 	static int inited = 0;
+	Dl_info dlinfo;
 	void *handle;
+	void *forcedunwind, *resume, *getcfa;
 
 	if (inited)
-		return;
-	inited = 1;
+	    return;
 	handle = RTLD_DEFAULT;
-	if ((uwl_forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind")) == NULL||
-	    (uwl_resume = dlsym(handle, "_Unwind_Resume")) == NULL ||
-	    (uwl_getcfa = dlsym(handle, "_Unwind_GetCFA")) == NULL) {
-		uwl_forcedunwind = NULL;
-		return;
+	if ((forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind")) != NULL) {
+	    if (dladdr(forcedunwind, &dlinfo)) {
+		if ((handle = dlopen(dlinfo.dli_fname, RTLD_LAZY)) != NULL) {
+		    forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind");
+		    resume = dlsym(handle, "_Unwind_Resume");
+		    getcfa = dlsym(handle, "_Unwind_GetCFA");
+		    if (forcedunwind != NULL && resume != NULL &&
+			getcfa != NULL) {
+			uwl_forcedunwind = forcedunwind;
+			uwl_resume = resume;
+			uwl_getcfa = getcfa;
+		    } else {
+			dlclose(handle);
+		    }
+		}
+	    }
 	}
+	inited = 1;
 }
 
 void