linux-kernel - Re: [PATCH V3] mfd: wm8994-core: Don't use managed regulator bulk get API

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Message-ID: <20161027102102.GE10423@vireshk-i7>
Date:   Thu, 27 Oct 2016 15:51:02 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:     Lee Jones <lee.jones@...aro.org>, linaro-kernel@...ts.linaro.org,
        broonie@...nel.org, patches@...nsource.wolfsonmicro.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] mfd: wm8994-core: Don't use managed regulator bulk
 get API

On 27-10-16, 10:14, Charles Keepax wrote:
> On Thu, Oct 27, 2016 at 09:09:30AM +0530, Viresh Kumar wrote:
> > The kernel WARNs and then crashes today if wm8994_device_init() fails
> > after calling devm_regulator_bulk_get().
> > 
> > That happens because there are multiple devices involved here and the
> > order in which resources are freed isn't correct.
> > 
> > The regulators are added as children of wm8994->dev.
> > devm_regulator_bulk_get() receives wm8994->dev as the device, though it
> > gets the same regulators which were added as children of wm8994->dev
> > earlier.
> > 
> > During failures, the children are removed first and the core eventually
> > calls regulator_unregister() for them. As regulator_put() was never done
> > for them (opposite of devm_regulator_bulk_get()), the kernel WARNs at
> > 
> > 	WARN_ON(rdev->open_count);
> > 
> > And eventually it crashes from debugfs_remove_recursive().
> > 
> > --------x------------------x----------------
> 
> The back track seems to have got really really long again.

Not just that, even the code moved a version back.

Sorry for the noise, the right version is sent now :(

-- 
viresh