linux-kernel - Re: [PATCH 21/38] workqueue: add missing put

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Message-ID: <52B313D8.6090508@linux.com>
Date:	Thu, 19 Dec 2013 16:42:16 +0100
From:	Levente Kurusa <levex@...ux.com>
To:	Tejun Heo <tj@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 21/38] workqueue: add missing put_device call

[+Cc Greg]

On 12/19/2013 04:34 PM, Tejun Heo wrote:
> Hello,
> 
> On Thu, Dec 19, 2013 at 10:31 AM, Levente Kurusa <levex@...ux.com> wrote:
>> The reason I removed the kfree() was because the put_device() will decrement
>> wq_dev->dev's reference count to zero (it is set to one by device_register) and hence the
>> wq_device_release() will be called. Now, this effectively does the same the kfree() call
>> would have done but also driver core is notified.
> 
> Yeah, I know it does the same thing. It's just not the right way to do it.
> 
>> Also, if you take a look at the comment for the device_register() function, it explicitly
>> says NOT to kfree the struct device, but instead call put_device() and let the device's release()
>> function take care.
> 
> Greg, the API as described by the comment is really weird and
> unconventional. Failed calls are not supposed to have side effects
> which require explicit cleanup. Can we please update the comment?
> 

Yes, it was already discussed that it would be more sane to have
device_register() call put_device() if it would fail, but Greg
said that the API was designed so that no kfree()s happen in the core.

-- 
Regards,
Levente Kurusa
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