linux-kernel - Re: [PATCH 0/4] treewide: add missing put

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Message-ID: <20131216181822.GA2522@kroah.com>
Date:	Mon, 16 Dec 2013 10:18:22 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Levente Kurusa <levex@...ux.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/4] treewide: add missing put_device calls

On Mon, Dec 16, 2013 at 07:11:21PM +0100, Levente Kurusa wrote:
> On 12/16/2013 06:58 PM, Greg Kroah-Hartman wrote:
> > On Mon, Dec 16, 2013 at 06:18:53PM +0100, Levente Kurusa wrote:
> >>>> IIRC, there are also a few where the device is also unregistered from
> >>>> the specific subsystem's core.
> >>>
> >>> Do you have a specific example of this?  This should happen in the
> >>> release function of the device already, not in some other code.
> >>>
> >> Character drivers who register with device_register() call cdev_del()
> >> when device_register() fails.
> > 
> > A cdev shouldn't be created until _after_ the device is successfully
> > registered, as it could be opened and accessed before the device is
> > registered.  That sounds like the drivers that do that should be fixed
> > (have an example of this somewhere?)
> 
> I did some research and it seems it has mostly been my false memory that made
> me think that. The only example I could find that did something like this
> was: drivers/scsi/osd/osd_uld.c at line 403.
> 
> When the device_register() fails it immediately jumps to a cdev_del();

That should be easy to reorginize to not do this (i.e. do the cdev_add()
call after the device_register() call, if needed.

thanks,

greg k-h
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