linux-kernel - Re: [PATCH] irqchip/gic-v4.1: Use readx_poll_timeout

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Message-ID: <2bff9c0af0aa5eeef44b381ee0f8a542@kernel.org>
Date:   Wed, 10 Jun 2020 16:02:54 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Zenghui Yu <yuzenghui@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, tglx@...utronix.de,
        jason@...edaemon.net, wanghaibin.wang@...wei.com,
        wangjingyi11@...wei.com
Subject: Re: [PATCH] irqchip/gic-v4.1: Use readx_poll_timeout_atomic() to fix
 sleep in atomic

Hi Zenghui,

On 2020-06-10 14:59, Zenghui Yu wrote:
> Hi Marc,
> 
> Sorry to ping you in the merge window, but ...
> 
> On 2020/6/5 13:23, Zenghui Yu wrote:
>> readx_poll_timeout() can sleep if @sleep_us is specified by the 
>> caller,
>> and is therefore unsafe to be used inside the atomic context, which is
>> this case when we use it to poll the GICR_VPENDBASER.Dirty bit in
>> irq_set_vcpu_affinity() callback.
> 
> this seems like an urgent thing to me. Without this patch, CPUs are
> easily to get stuck on my board with GICv4.1 enabled. So it'd be good 
> if
> you can have a look and take this as a fix (if it is correct).

No worries. I've earmarked the patch for -rc1 already, just haven't got
a chance to build the branch yet (a bit busy on the KVM side).

I'll probably update the branch tonight or tomorrow.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...