linux-kernel - Re: [External] Re: [RFC] genirq: Fix lockup in handle_edge

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Message-ID: <33834852-af8f-451d-9a39-8787330c2694@google.com>
Date: Tue, 8 Jul 2025 09:43:06 +0800
From: Liangyan <liangyan.peng@...edance.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org, Yicong Shen
 <shenyicong.1023@...edance.com>, ziqianlu@...edance.com,
 songmuchun@...edance.com, yuanzhu@...edance.com
Subject: Re: [External] Re: [RFC] genirq: Fix lockup in handle_edge_irq



On 2025/7/4 22:42, Thomas Gleixner wrote:
> 
> So playing games with the unmask is not really feasible. But let's take
> a step back and look at the actual problem.
> 
> It only happens when the interrupt affinity is moved or the interrupt
> has multiple target CPUs enabled in the effective affinity mask. x86 and
> arm64 enforce the effective affinity to be a single CPU, so on those
> architectures the problem only arises when the interrupt affinity
> changes.
> 
> Now we can use that fact and check whether the CPU, which observes
> INPROGRESS, is the target CPU in the effective affinity mask. If so,
> then the obvious cure is to busy poll the INPROGRESS flag instead of
> doing the mask()/PENDING/unmask() dance.
> 
> Something like the uncompiled and therefore untested patch below should
> do the trick. If you find bugs in it, you can keep and fix them :)
> 
Hello Thomas,

After over a day of testing the patch, the softlockup issue has not
recurred. This confirms that your patch should fix the problem. Thanks.
Would you consider upstreaming this patch?

Regards，
Liangyan