linux-kernel - Re: [PATCH 2/6] drivers/base: add bus for System-on-Chip devices

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Date:	Tue, 18 Oct 2011 15:56:49 +0100
From:	Jamie Iles <jamie@...ieiles.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Jamie Iles <jamie@...ieiles.com>, Lee Jones <lee.jones@...aro.org>,
	Greg KH <gregkh@...e.de>, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linus.walleij@...ricsson.com
Subject: Re: [PATCH 2/6] drivers/base: add bus for System-on-Chip devices

On Tue, Oct 18, 2011 at 04:53:09PM +0200, Arnd Bergmann wrote:
> On Tuesday 18 October 2011, Jamie Iles wrote:
> > Also, (and I'm right at the edge of my knowledge here!) wouldn't you 
> > also need to add reference counting of the module when 
> > creating/destroying a soc device to prevent the module and bus 
> > disappearing whilst you had devices with a reference to it?
> 
> No, that's not necessary in a case like this: The bus module remains
> pinned by the reference of the module calling it on each exported
> symbol that is referenced. The reference counting is only needed
> if driver module provides function pointers to the bus module
> that might be in the middle of getting called while the driver is
> removed. We have this case with the ux500_get_process function
> that may be called through sysfs, so that would be a bug if the
> code calling device_create_file() was in a module.

Ahh, okay that makes sense.  Thanks for the explanation Arnd.

Jamie
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