linux-kernel - Re: [PATCH RFC 1/3] spmi: Linux driver framework for SPMI

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Message-ID: <20130816202110.GJ4035@joshc.qualcomm.com>
Date:	Fri, 16 Aug 2013 15:21:10 -0500
From:	Josh Cartwright <joshc@...eaurora.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-arm-msm@...r.kernel.org,
	Sagar Dharia <sdharia@...eaurora.org>,
	Gilad Avidov <gavidov@...eaurora.org>,
	Michael Bohan <mbohan@...eaurora.org>
Subject: Re: [PATCH RFC 1/3] spmi: Linux driver framework for SPMI

On Fri, Aug 16, 2013 at 11:49:21AM -0700, Greg Kroah-Hartman wrote:
> On Fri, Aug 09, 2013 at 01:37:09PM -0700, Josh Cartwright wrote:
> > +++ b/drivers/spmi/spmi.c
> > @@ -0,0 +1,449 @@
[..]
> > +static void spmi_ctrl_release(struct device *dev)
> > +{
> > +	struct spmi_controller *ctrl = to_spmi_controller(dev);
> > +	complete(&ctrl->dev_released);
> 
> When is this memory going to be freed?
> 
> Ah, you think it will be when you remove the device later on:
> 
> > +int spmi_del_controller(struct spmi_controller *ctrl)
> > +{
> > +	struct spmi_controller *found;
> > +
> > +	if (!ctrl)
> > +		return -EINVAL;
> > +
> > +	/* Check that the ctrl has been added */
> > +	mutex_lock(&board_lock);
> > +	found = idr_find(&ctrl_idr, ctrl->nr);
> > +	mutex_unlock(&board_lock);
> > +
> > +	if (found != ctrl)
> > +		return -EINVAL;
> > +
> > +	spmi_dfs_del_controller(ctrl);
> > +
> > +	/* Remove all the clients associated with this controller */
> > +	mutex_lock(&board_lock);
> > +	bus_for_each_dev(&spmi_bus_type, NULL, ctrl, spmi_ctrl_remove_device);
> > +	idr_remove(&ctrl_idr, ctrl->nr);
> > +	mutex_unlock(&board_lock);
> > +
> > +	init_completion(&ctrl->dev_released);
> > +	device_unregister(&ctrl->dev);
> > +	wait_for_completion(&ctrl->dev_released);
> 
> But you just leaked memory, right?
> 
> You should never have to wait for this to happen, why did you need to
> add this?  Why not just a simple call to kfree() in the release
> function?

Unfortunately, the reason why this was necessary may be lost to history.  :(

I'll do some testing with the completion removed and a simple kfree() in
the release and see if there is any fallout.

Thanks,
  Josh

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