linux-kernel - [PATCH] xen: wait up to 5 minutes for device connection

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Date:	Fri,  3 Jul 2009 15:12:51 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	pbonzini@...hat.com,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: [PATCH] xen: wait up to 5 minutes for device connection

Increases the device timeout from 10s to 5 minutes, giving the user a visual
indication during that time in case there are problems.  The patch is a
backport of changesets 144, 146, 150 and 909 in the Xenbits tree.

Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 drivers/xen/xenbus/xenbus_probe.c |   42 +++++++++++++++++++++++++-----------
 1 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index d42e25d..4f69159 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -843,7 +843,7 @@ postcore_initcall(xenbus_probe_init);
 
 MODULE_LICENSE("GPL");
 
-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;
@@ -861,14 +861,15 @@ static int is_disconnected_device(struct device *dev, void *data)
 		return 0;
 
 	xendrv = to_xenbus_driver(dev->driver);
-	return (xendev->state != XenbusStateConnected ||
-		(xendrv->is_ready && !xendrv->is_ready(xendev)));
+	return (xendev->state < XenbusStateConnected ||
+		(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)
 {
 	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)
@@ -884,10 +885,13 @@ static int print_device_status(struct device *dev, void *data)
 		/* Information only: is this too noisy? */
 		printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
 		       xendev->nodename);
-	} else if (xendev->state != XenbusStateConnected) {
+	} else if (xendev->state < XenbusStateConnected) {
+		enum xenbus_state rstate = XenbusStateUnknown;
+		if (xendev->otherend)
+			rstate = xenbus_read_driver_state(xendev->otherend);
 		printk(KERN_WARNING "XENBUS: Timeout connecting "
-		       "to device: %s (state %d)\n",
-		       xendev->nodename, xendev->state);
+		       "to device: %s (local state %d, remote state %d)\n",
+		       xendev->nodename, xendev->state, rstate);
 	}
 
 	return 0;
@@ -897,7 +901,7 @@ static int print_device_status(struct device *dev, void *data)
 static int ready_to_wait_for_devices;
 
 /*
- * On a 10 second timeout, wait for all devices currently configured.  We need
+ * On a 5-minute timeout, wait for all devices currently configured.  We need
  * to do this to guarantee that the filesystems and / or network devices
  * needed for boot are available, before we can allow the boot to proceed.
  *
@@ -912,18 +916,30 @@ static int ready_to_wait_for_devices;
  */
 static void wait_for_devices(struct xenbus_driver *xendrv)
 {
-	unsigned long timeout = jiffies + 10*HZ;
+	unsigned long start = jiffies;
 	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
+	unsigned int seconds_waited = 0;
 
 	if (!ready_to_wait_for_devices || !xen_domain())
 		return;
 
-	while (exists_disconnected_device(drv)) {
-		if (time_after(jiffies, timeout))
-			break;
+	while (exists_connecting_device(drv)) {
+		if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
+			if (!seconds_waited)
+				printk(KERN_WARNING "XENBUS: Waiting for "
+				       "devices to initialise: ");
+			seconds_waited += 5;
+			printk("%us...", 300 - seconds_waited);
+			if (seconds_waited == 300)
+				break;
+		}
+
 		schedule_timeout_interruptible(HZ/10);
 	}
 
+	if (seconds_waited)
+		printk("\n");
+
 	bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 			 print_device_status);
 }
-- 
1.6.2.5

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