linux-kernel - [PATCH v2] Drivers: hv: vmbus: incorrect device name is printed when child device is unregistered

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Date:	Fri, 14 Jun 2013 23:13:35 +0000
From:	Fernando Soto <fsoto@...ecatnetworks.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Haiyang Zhang <haiyangz@...rosoft.com>,
	KY Srinivasan <kys@...rosoft.com>,
	"Greg KH (gregkh@...uxfoundation.org)" <gregkh@...uxfoundation.org>
Subject: [PATCH v2] Drivers: hv: vmbus: incorrect device name is printed
 when child device is unregistered

From: Fernando Soto <fsoto@...ecatnetworks.com> 
Please CC me, I am not subscribed to the list.

Whenever a device is unregistered in vmbus_device_unregister (drivers/hv/vmbus_drv.c), the device name in the log message may contain garbage as the memory has already been freed by the time pr_info is called. Log example:
 [ 3149.170475] hv_vmbus: child device àõsèè0_5 unregistered

By logging the message just before calling device_unregister, the correct device name is printed:
[ 3145.034652] hv_vmbus: child device vmbus_0_5 unregistered

Also changing register & unregister messages to debug to avoid unnecessarily cluttering the kernel log.

Signed-off-by: Fernando M Soto <fsoto@...ecatnetworks.com>
--- linux-3.10-rc5/drivers/hv/vmbus_drv.c.orig	2013-06-13 19:20:55.359511352 -0400
+++ linux-3.10-rc5/drivers/hv/vmbus_drv.c	2013-06-14 19:00:21.722105728 -0400
@@ -686,7 +686,7 @@ int vmbus_device_register(struct hv_devi
 	if (ret)
 		pr_err("Unable to register child device\n");
 	else
-		pr_info("child device %s registered\n",
+		pr_debug("child device %s registered\n",
 			dev_name(&child_device_obj->device));
 
 	return ret;
@@ -698,14 +698,14 @@ int vmbus_device_register(struct hv_devi
  */
 void vmbus_device_unregister(struct hv_device *device_obj)
 {
+	pr_debug("child device %s unregistered\n",
+		dev_name(&device_obj->device));
+
 	/*
 	 * Kick off the process of unregistering the device.
 	 * This will call vmbus_remove() and eventually vmbus_device_release()
 	 */
 	device_unregister(&device_obj->device);
-
-	pr_info("child device %s unregistered\n",
-		dev_name(&device_obj->device));
 }
 
 
--
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