From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 13 Aug 2009 18:00:24 +0200
Subject: [xen] fix timeout with PV guest and physical CDROM
Message-id: 1250179227-23431-1-git-send-email-pbonzini@redhat.com
O-Subject: [RHEL5.5 PATCH] BZ506899: fix timeout with PV guest and physical CDROM
Bugzilla: 506899
RH-Acked-by: Chris Lalancette <clalance@redhat.com>
RH-Acked-by: Markus Armbruster <armbru@redhat.com>

Bugzilla: https://bugzilla.redhat.com/attachment.cgi?bugid=506899

Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1927355

Upstream: http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev=909

Specifying a physical CDROM in the configuration of a PV guest, like

    disk = ['tap:aio:/....,xvda,w', 'phy:/dev/cdrom,hdc:cdrom,r' ]

will cause the 300 seconds timeout to occur if there is no physical CDROM
in the tray.  The bug is due to the device being Closed (as shown by the
timeout message) but not ready.  The configuration is quite bogus, but
this is a regression and the fix is easy and safe: only check is_ready
for connected devices.

Tested by me.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index cb98b21..ba02690 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -1222,7 +1222,7 @@ int xenbus_init(void)
 }
 #endif
 
-static int is_disconnected_device(struct device *dev, void *data)
+static int is_device_connecting(struct device *dev, void *data)
 {
 	struct xenbus_device *xendev = to_xenbus_device(dev);
 	struct device_driver *drv = data;
@@ -1241,16 +1241,17 @@ static int is_disconnected_device(struct device *dev, void *data)
 
 	xendrv = to_xenbus_driver(dev->driver);
 	return (xendev->state < XenbusStateConnected ||
-		(xendrv->is_ready && !xendrv->is_ready(xendev)));
+		(xendev->state == XenbusStateConnected &&
+		 xendrv->is_ready && !xendrv->is_ready(xendev)));
 }
 
-static int exists_disconnected_device(struct device_driver *drv)
+static int exists_connecting_device(struct device_driver *drv)
 {
         if (xenbus_frontend.error)
                 return xenbus_frontend.error;
 
 	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
-				is_disconnected_device);
+				is_device_connecting);
 }
 
 static int print_device_status(struct device *dev, void *data)
@@ -1304,7 +1305,7 @@ static void wait_for_devices(struct xenbus_driver *xendrv)
 	if (!ready_to_wait_for_devices || !is_running_on_xen())
 		return;
 
-	while (exists_disconnected_device(drv)) {
+	while (exists_connecting_device(drv)) {
 		if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
 			if (!seconds_waited)
 				printk(KERN_WARNING "XENBUS: Waiting for "