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Date:   Tue, 26 Jul 2022 13:39:13 +0530
From:   Manivannan Sadhasivam <mani@kernel.org>
To:     Kalle Valo <kvalo@kernel.org>
Cc:     Qiang Yu <quic_qianyu@quicinc.com>, quic_hemantk@quicinc.com,
        loic.poulain@linaro.org, quic_jhugo@quicinc.com,
        mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, quic_cang@quicinc.com,
        ath11k@lists.infradead.org
Subject: Re: [PATCH v4 1/1] bus: mhi: host: Move IRQ allocation to controller
 registration phase
Message-ID: <20220726080913.GF5522@workstation>
References: <1655952183-66792-1-git-send-email-quic_qianyu@quicinc.com>
 <20220624072740.GA12171@thinkpad>
 <87k08an038.fsf@kernel.org>
 <20220720093909.GA5747@thinkpad>
 <063fe6bf-11b1-1724-058f-0fed7247906e@quicinc.com>
 <20220721101914.GC36189@thinkpad>
 <87wnc1qdhz.fsf@kernel.org>
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On Mon, Jul 25, 2022 at 09:00:08PM +0300, Kalle Valo wrote:
> Manivannan Sadhasivam <mani@kernel.org> writes:
> 
> > On Wed, Jul 20, 2022 at 05:47:37PM +0800, Qiang Yu wrote:
> >
> >> 
> >> On 7/20/2022 5:39 PM, Manivannan Sadhasivam wrote:
> >> > On Mon, Jul 18, 2022 at 02:15:23PM +0300, Kalle Valo wrote:
> >> > > + ath11k list
> >> > > 
> >> > > Manivannan Sadhasivam <mani@kernel.org> writes:
> >> > > 
> >> > > > On Thu, Jun 23, 2022 at 10:43:03AM +0800, Qiang Yu wrote:
> >> > > > > During runtime, the MHI endpoint may be powered up/down several times.
> >> > > > > So instead of allocating and destroying the IRQs all the time, let's just
> >> > > > > enable/disable IRQs during power up/down.
> >> > > > > 
> >> > > > > The IRQs will be allocated during mhi_register_controller() and freed
> >> > > > > during mhi_unregister_controller(). This works well for things like PCI
> >> > > > > hotplug also as once the PCI device gets removed, the controller will
> >> > > > > get unregistered. And once it comes back, it will get registered back
> >> > > > > and even if the IRQ configuration changes (MSI), that will get accounted.
> >> > > > > 
> >> > > > > Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
> >> > > > Applied to mhi-next!
> >> > > I did a bisect and this patch breaks ath11k during rmmod. I'm on
> >> > > vacation right now so I can't investigate in detail but more info below.
> >> > > 
> >> > I just tested linux-next/master next-20220718 on my NUC with QCA6390, but I'm
> >> > not able to reproduce the issue during rmmod! Instead I couldn't connect to AP.
> >> 
> >> I suspect that in __free_irq(), if CONFIG_DEBUG_SHIRQ is enabled, irq
> >> handler for a shared IRQ will be invoked and null pointer access happen.
> >> 
> >> #ifdef CONFIG_DEBUG_SHIRQ
> >> ?? ?/*
> >> ?? ? * It's a shared IRQ -- the driver ought to be prepared for an IRQ
> >> ?? ? * event to happen even now it's being freed, so let's make sure that
> >> ?? ? * is so by doing an extra call to the handler ....
> >> ?? ? *
> >> ?? ? * ( We do this after actually deregistering it, to make sure that a
> >> ?? ? *?? 'real' IRQ doesn't run in parallel with our fake. )
> >> ?? ? */
> >> ?? ?if (action->flags & IRQF_SHARED) {
> >> ?? ???? local_irq_save(flags);
> >> ?? ???? action->handler(irq, dev_id);
> >> ?? ???? local_irq_restore(flags);
> >> ?? ?}
> >> #endif
> >> 
> >
> > Ah yes, after enabling CONFIG_DEBUG_SHIRQ I could reproduce the issue.
> 
> So how to fix this regression? (If there's already a fix I might have
> missed it as I came back only today)
> 

Copied you on the fix patch. Please test and let us know!

Thanks,
Mani

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> 
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