linux-kernel - Re: [PATCH 3/4] mwifiex: Flag wake-up interrupt as IRQ_NOAUTOEN rather than disabling it too late

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Date:   Tue, 26 Feb 2019 15:34:14 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Amitkumar Karwar <amitkarwar@...il.com>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Ganapathi Bhat <gbhat@...vell.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Kalle Valo <kvalo@...eaurora.org>,
        Nishant Sarmukadam <nishants@...vell.com>,
        Rob Herring <robh+dt@...nel.org>,
        Xinming Hu <huxinming820@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 3/4] mwifiex: Flag wake-up interrupt as IRQ_NOAUTOEN
 rather than disabling it too late

On Tue, Feb 26, 2019 at 03:31:31PM -0800, Brian Norris wrote:
> Hi Marc,
> 
> On Sun, Feb 24, 2019 at 02:04:25PM +0000, Marc Zyngier wrote:
> > The mwifiex driver makes unsafe assumptions about the state of the
> > wake-up interrupt. It requests it and only then disable it. Of
> > course, the interrupt may be screaming for whatever reason at that
> > time, and the handler will then be called without the interrupt
> > having been registered with the PM/wakeup subsystem. Oops.
> > 
> > The right way to handle this kind of situation is to flag the
> > interrupt with IRQ_NOAUTOEN before requesting it. It will then
> > stay disabled until someone (the wake-up subsystem) enables it.
> > 
> > Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> 
> This could be:
> 
> Fixes: 853402a00823 ("mwifiex: Enable WoWLAN for both sdio and pcie")

Also, this comes after a different change (that's not quite as clearly a
backport-able bugfix). Perhaps it should go first in the series?

Brian

> although, that was just borrowing the existing antipattern from SDIO
> code..
> 
> Reviewed-by: Brian Norris <briannorris@...omium.org>
> 
> Thanks.
> 
> > ---
> >  drivers/net/wireless/marvell/mwifiex/main.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
> > index 2105c2b7c627..82cf35e50579 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/main.c
> > +++ b/drivers/net/wireless/marvell/mwifiex/main.c
> > @@ -1610,6 +1610,7 @@ static void mwifiex_probe_of(struct mwifiex_adapter *adapter)
> >  			 "wake-up interrupt outside 'wake-up' subnode of %pOF\n",
> >  			 adapter->dt_node);
> >  
> > +	irq_set_status_flags(adapter->irq_wakeup, IRQ_NOAUTOEN);
> >  	ret = devm_request_irq(dev, adapter->irq_wakeup,
> >  			       mwifiex_irq_wakeup_handler, IRQF_TRIGGER_LOW,
> >  			       "wifi_wake", adapter);
> > @@ -1619,7 +1620,6 @@ static void mwifiex_probe_of(struct mwifiex_adapter *adapter)
> >  		goto err_exit;
> >  	}
> >  
> > -	disable_irq(adapter->irq_wakeup);
> >  	if (device_init_wakeup(dev, true)) {
> >  		dev_err(dev, "fail to init wakeup for mwifiex\n");
> >  		goto err_exit;
> > -- 
> > 2.20.1
> >