linux-kernel - Re: [PATCH 2/2] pda_power: Unregister USB notifier in pda_power

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Message-ID: <CA+rthh__aRaY+DQ7drj_MPB3Gb35RFFUCd50ZN_pQR3OGr2GEw@mail.gmail.com>
Date:	Tue, 15 Apr 2014 00:07:13 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	Felipe Balbi <balbi@...com>
Cc:	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	PaX Team <pageexec@...email.hu>,
	Anton Vorontsov <anton@...msg.org>
Subject: Re: [PATCH 2/2] pda_power: Unregister USB notifier in pda_power_remove()

On 14 April 2014 23:35, Felipe Balbi <balbi@...com> wrote:
> On Sun, Mar 30, 2014 at 03:34:15PM +0200, Mathias Krause wrote:
>> If we've registered a notifier in pda_power_probe() we must deregister
>> it in pda_power_remove() to not let it work on stale data like, e.g.,
>> the charger timer.
>>
>> Cc: Felipe Balbi <balbi@...com>
>> Cc: Anton Vorontsov <anton@...msg.org>
>> Signed-off-by: Mathias Krause <minipli@...glemail.com>
>> ---
>>  drivers/power/pda_power.c |    5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/power/pda_power.c b/drivers/power/pda_power.c
>> index 87a963d0a8..aba23d6848 100644
>> --- a/drivers/power/pda_power.c
>> +++ b/drivers/power/pda_power.c
>> @@ -430,6 +430,11 @@ static int pda_power_remove(struct platform_device *pdev)
>>       if (pdata->is_ac_online && ac_irq)
>>               free_irq(ac_irq->start, &pda_psy_ac);
>>
>> +#if IS_ENABLED(CONFIG_USB_PHY)
>> +     if (!IS_ERR_OR_NULL(transceiver) && pdata->use_otg_notifier)
>
> IS_ERR() should be enough here.

That's true! The usb_get_phy() call in pda_power_probe() will always
return a valid pointer or an ERR_PTR() -- never NULL. Albeit, looking
at usb_get_phy(), it contains another bug, returning a valid pointer,
even when the try_module_get() call fails. *sigh* It should set ptr to
an ERR_PTR() in this case.

Anyway, probably all the transceiver checks in pda_power.c can be
changed to IS_ERR() checks. The reason I am using IS_ERR_OR_NULL() in
my patch is that I just copied the test from a few lines below. I'll
create a follow up patch in case somebody cares about this series in
the first place.

>
>> +             usb_unregister_notifier(transceiver, &otg_nb);
>> +#endif
>> +
>>       if (polling)
>>               del_timer_sync(&polling_timer);
>>       del_timer_sync(&charger_timer);
>> --
>> 1.7.10.4
>>
>
> --
> balbi

Thanks,
Mathias
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