From owner-p4-projects@FreeBSD.ORG  Thu Mar 29 05:04:34 2007
Return-Path: <owner-p4-projects@FreeBSD.ORG>
X-Original-To: p4-projects@freebsd.org
Delivered-To: p4-projects@freebsd.org
Received: by hub.freebsd.org (Postfix, from userid 32767)
	id 9477316A404; Thu, 29 Mar 2007 05:04:34 +0000 (UTC)
X-Original-To: perforce@freebsd.org
Delivered-To: perforce@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 6E49316A402
	for <perforce@freebsd.org>; Thu, 29 Mar 2007 05:04:34 +0000 (UTC)
	(envelope-from scottl@freebsd.org)
Received: from repoman.freebsd.org (repoman.freebsd.org [69.147.83.41])
	by mx1.freebsd.org (Postfix) with ESMTP id 5FECE13C459
	for <perforce@freebsd.org>; Thu, 29 Mar 2007 05:04:34 +0000 (UTC)
	(envelope-from scottl@freebsd.org)
Received: from repoman.freebsd.org (localhost [127.0.0.1])
	by repoman.freebsd.org (8.13.8/8.13.8) with ESMTP id l2T54Til089767
	for <perforce@freebsd.org>; Thu, 29 Mar 2007 05:04:29 GMT
	(envelope-from scottl@freebsd.org)
Received: (from perforce@localhost)
	by repoman.freebsd.org (8.13.8/8.13.8/Submit) id l2T54ThK089734
	for perforce@freebsd.org; Thu, 29 Mar 2007 05:04:29 GMT
	(envelope-from scottl@freebsd.org)
Date: Thu, 29 Mar 2007 05:04:29 GMT
Message-Id: <200703290504.l2T54ThK089734@repoman.freebsd.org>
X-Authentication-Warning: repoman.freebsd.org: perforce set sender to
	scottl@freebsd.org using -f
From: Scott Long <scottl@FreeBSD.org>
To: Perforce Change Reviews <perforce@freebsd.org>
Cc: 
Subject: PERFORCE change 116814 for review
X-BeenThere: p4-projects@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: p4 projects tree changes <p4-projects.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/p4-projects>,
	<mailto:p4-projects-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/p4-projects>
List-Post: <mailto:p4-projects@freebsd.org>
List-Help: <mailto:p4-projects-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/p4-projects>,
	<mailto:p4-projects-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 29 Mar 2007 05:04:34 -0000

http://perforce.freebsd.org/chv.cgi?CH=116814

Change 116814 by scottl@scottl-x64 on 2007/03/29 05:04:02

	The changer-mini-scheduler is fundamentally broken; as soon as an
	I/O needs to be deferred, an unescapable spinloop is triggered with
	the SIM lock held.  Avoid this by moving a code block around that
	probably should have been moved around anyways.

Affected files ...

.. //depot/projects/scottl-camlock/src/sys/cam/scsi/scsi_cd.c#16 edit

Differences ...

==== //depot/projects/scottl-camlock/src/sys/cam/scsi/scsi_cd.c#16 (text+ko) ====

@@ -1165,6 +1165,14 @@
 	 */
 	if (changer->devq.qfrozen_cnt > 0) {
 
+		/*
+		 * We always need to reset the frozen count and clear the
+		 * active flag.
+		 */
+		changer->devq.qfrozen_cnt--;
+		changer->cur_device->flags &= ~CD_FLAG_ACTIVE;
+		changer->cur_device->flags &= ~CD_FLAG_SCHED_ON_COMP;
+
 		if (changer->cur_device->outstanding_cmds > 0) {
 			changer->cur_device->flags |= CD_FLAG_SCHED_ON_COMP;
 			changer->cur_device->bufs_left = 
@@ -1179,14 +1187,6 @@
 		}
 
 		/*
-		 * We always need to reset the frozen count and clear the
-		 * active flag.
-		 */
-		changer->devq.qfrozen_cnt--;
-		changer->cur_device->flags &= ~CD_FLAG_ACTIVE;
-		changer->cur_device->flags &= ~CD_FLAG_SCHED_ON_COMP;
-
-		/*
 		 * Check to see whether the current device has any I/O left
 		 * to do.  If so, requeue it at the end of the queue.  If
 		 * not, there is no need to requeue it.