linux-kernel - Re: [PATCH] pinctrl: bcm2835: Fix a few error paths

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Message-ID: <YfQZT3NokrgF5OQA@smile.fi.intel.com>
Date:   Fri, 28 Jan 2022 18:26:55 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        "maintainer:BROADCOM BCM281XX/BCM11XXX/BCM216XX ARM ARCHITE..." 
        <bcm-kernel-feedback-list@...adcom.com>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Phil Elwell <phil@...pberrypi.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Jason Wang <wangborong@...rlc.com>,
        Marc Zyngier <maz@...nel.org>,
        "open list:PIN CONTROL SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] pinctrl: bcm2835: Fix a few error paths

On Fri, Jan 28, 2022 at 08:12:02AM -0800, Florian Fainelli wrote:
> On 1/28/2022 6:35 AM, Andy Shevchenko wrote:
> > On Thu, Jan 27, 2022 at 01:50:31PM -0800, Florian Fainelli wrote:
> > > After commit 266423e60ea1 ("pinctrl: bcm2835: Change init order for gpio
> > > hogs") a few error paths would not unwind properly the registration of
> > > gpio ranges. Correct that by assigning a single error label and goto it
> > > whenever we encounter a fatal error.
> > 
> > >   1 file changed, 15 insertions(+), 8 deletions(-)
> > 
> > While this seems legit per se, my eyes caught this:
> > 
> > 
> > >   	if (!girq->parents) {
> > > -		pinctrl_remove_gpio_range(pc->pctl_dev, &pc->gpio_range);
> > > -		return -ENOMEM;
> > > +		err = -ENOMEM;
> > > +		goto out_remove;
> > 
> > Non-devm....
> > 
> > >   	}
> > >   	if (is_7211) {
> > >   		pc->wake_irq = devm_kcalloc(dev, BCM2835_NUM_IRQS,
> > >   					    sizeof(*pc->wake_irq),
> > >   					    GFP_KERNEL);
> > 
> > ...followed by devm.
> > 
> > It means more ordering bugs in the ->remove() and error path are lurking
> > around. Can you double check and be sure that we do not have a case where
> > non-devm registration code followed by devm?
> 
> It seems to me like we are fine with the patch as is, because:
> 
> - girq->parents is allocated with devm
> - pc->wake_irq is allocated with devm
> - name is allocated with devm
> 
> and those are the only variables being allocated for which we also process
> an error handling path.

Okay, thanks.

My worries that it might be the case when the GPIO ranges have been removed by
explicit call in ->remove() followed by some interrupt or so and oops or
misbehaviour because of that.

-- 
With Best Regards,
Andy Shevchenko