linux-kernel - [PATCH] driver core: fix device

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Date:	Sun, 11 Mar 2007 15:36:19 +0300
From:	Dmitriy Monakhov <dmonakhov@...ru>
To:	Dmitriy Monakhov <dmonakhov@...ru>
Cc:	Greg Kroah-Hartman <gregkh@...e.de>, linux-kernel@...r.kernel.org,
	James Simmons <jsimmons@...radead.org>
Subject: [PATCH] driver core: fix device_add error path

Dmitriy Monakhov <dmonakhov@...ru> writes:

> Greg Kroah-Hartman <gregkh@...e.de> writes:
>
>> From: James Simmons <jsimmons@...radead.org>
>>
>> When a device fails to register the class symlinks where not cleaned up.
>> This left a symlink in the /sys/class/"device"/ directory that pointed
>> to no where. This caused the sysfs_follow_link Oops I reported earlier.
>> This patch cleanups up the symlink. Please apply. Thank you.
>>
>> Signed-Off: James Simmons <jsimmons@...radead.org>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
>> ---
>>  drivers/base/core.c |   31 ++++++++++++++++++++++++++++++-
>>  1 files changed, 30 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index d04fd33..cf2a398 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -637,12 +637,41 @@ int device_add(struct device *dev)
>>  					     BUS_NOTIFY_DEL_DEVICE, dev);
>>  	device_remove_groups(dev);
>>   GroupError:
>> - 	device_remove_attrs(dev);
>> +	device_remove_attrs(dev);
>>   AttrsError:
>>  	if (dev->devt_attr) {
>>  		device_remove_file(dev, dev->devt_attr);
>>  		kfree(dev->devt_attr);
>>  	}
>> +
>> +	if (dev->class) {
>> +		sysfs_remove_link(&dev->kobj, "subsystem");
>> +		/* If this is not a "fake" compatible device, remove the
>> +		 * symlink from the class to the device. */
>> +		if (dev->kobj.parent != &dev->class->subsys.kset.kobj)
>> +			sysfs_remove_link(&dev->class->subsys.kset.kobj,
>> +					  dev->bus_id);
>> +#ifdef CONFIG_SYSFS_DEPRECATED
>> +		if (parent) {
>> +			char *class_name = make_class_name(dev->class->name,
>> +							   &dev->kobj);
>> +			if (class_name)
>> +				sysfs_remove_link(&dev->parent->kobj,
>> +						  class_name);
>> +			kfree(class_name);
>> +			sysfs_remove_link(&dev->kobj, "device");
>> +		}
>> +#endif
>> +
> <<<<< block begin
>> +		down(&dev->class->sem);
>> +		/* notify any interfaces that the device is now gone */
>> +		list_for_each_entry(class_intf, &dev->class->interfaces, node)
>> +			if (class_intf->remove_dev)
>> +				class_intf->remove_dev(dev, class_intf);
>> +		/* remove the device from the class list */
>> +		list_del_init(&dev->node);
>> +		up(&dev->class->sem);
> <<<<<< block end 
> May be i've missed something, but i'm confuesd a litle bit.
> For example if error happens while device_pm_add() we jump to label "PMError"
> and code from block above will be executed (device will be remove from list),
> but this device wasn't added to this list yet!
I've check it one more time, code it really broken!, and i think i understand how
this can happen ....
it look like full code chunck was copy-pasted from device_del(), but in case of 
device_add() error path, device was't added to dev->class->devices list yet.
Folowing patch fix this copy-paste error:

 [PATCH] driver core: fix device_add error path

 - At the moment we jump here device was't added to
   dev->class->devices list yet.

Signed-off-by: Monakhov Dmitriy <dmonakhov@...nvz.org>
---
 drivers/base/core.c |    9 ---------
 1 files changed, 0 insertions(+), 9 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 142c222..7d2459b 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -684,15 +684,6 @@ int device_add(struct device *dev)
 #endif
 			sysfs_remove_link(&dev->kobj, "device");
 		}
-
-		down(&dev->class->sem);
-		/* notify any interfaces that the device is now gone */
-		list_for_each_entry(class_intf, &dev->class->interfaces, node)
-			if (class_intf->remove_dev)
-				class_intf->remove_dev(dev, class_intf);
-		/* remove the device from the class list */
-		list_del_init(&dev->node);
-		up(&dev->class->sem);
 	}
  ueventattrError:
 	device_remove_file(dev, &dev->uevent_attr);
-- 
1.5.0.1


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