From owner-svn-src-all@FreeBSD.ORG  Sun Oct  5 07:21:42 2014
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id 396EF229;
 Sun,  5 Oct 2014 07:21:42 +0000 (UTC)
Received: from svn.freebsd.org (svn.freebsd.org
 [IPv6:2001:1900:2254:2068::e6a:0])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 2684EE34;
 Sun,  5 Oct 2014 07:21:42 +0000 (UTC)
Received: from svn.freebsd.org ([127.0.1.70])
 by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id s957Lg2P018836;
 Sun, 5 Oct 2014 07:21:42 GMT (envelope-from mjg@FreeBSD.org)
Received: (from mjg@localhost)
 by svn.freebsd.org (8.14.9/8.14.9/Submit) id s957Lgeg018835;
 Sun, 5 Oct 2014 07:21:42 GMT (envelope-from mjg@FreeBSD.org)
Message-Id: <201410050721.s957Lgeg018835@svn.freebsd.org>
X-Authentication-Warning: svn.freebsd.org: mjg set sender to mjg@FreeBSD.org
 using -f
From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Sun, 5 Oct 2014 07:21:42 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r272560 - head/sys/kern
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
 user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all/>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 05 Oct 2014 07:21:42 -0000

Author: mjg
Date: Sun Oct  5 07:21:41 2014
New Revision: 272560
URL: https://svnweb.freebsd.org/changeset/base/272560

Log:
  Avoid unnecessary ppeers_lock acquisition in exit1.
  
  MFC after:	1 week

Modified:
  head/sys/kern/kern_exit.c

Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c	Sun Oct  5 06:28:53 2014	(r272559)
+++ head/sys/kern/kern_exit.c	Sun Oct  5 07:21:41 2014	(r272560)
@@ -265,8 +265,8 @@ exit1(struct thread *td, int rv)
 	AUDIT_SYSCALL_EXIT(0, td);
 #endif
 
-	/* Are we a task leader? */
-	if (p == p->p_leader) {
+	/* Are we a task leader with peers? */
+	if (p->p_peers != NULL && p == p->p_leader) {
 		mtx_lock(&ppeers_lock);
 		q = p->p_peers;
 		while (q != NULL) {
@@ -337,15 +337,17 @@ exit1(struct thread *td, int rv)
 	/*
 	 * Remove ourself from our leader's peer list and wake our leader.
 	 */
-	mtx_lock(&ppeers_lock);
-	if (p->p_leader->p_peers) {
-		q = p->p_leader;
-		while (q->p_peers != p)
-			q = q->p_peers;
-		q->p_peers = p->p_peers;
-		wakeup(p->p_leader);
+	if (p->p_leader->p_peers != NULL) {
+		mtx_lock(&ppeers_lock);
+		if (p->p_leader->p_peers != NULL) {
+			q = p->p_leader;
+			while (q->p_peers != p)
+				q = q->p_peers;
+			q->p_peers = p->p_peers;
+			wakeup(p->p_leader);
+		}
+		mtx_unlock(&ppeers_lock);
 	}
-	mtx_unlock(&ppeers_lock);
 
 	vmspace_exit(td);