linux-kernel - Re: [PATCH 2/2] KVM: Guard cpusmask NULL check with CONFIG_CPUMASK

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Message-ID: <878s0ojygp.fsf@vitty.brq.redhat.com>
Date:   Thu, 26 Aug 2021 12:24:06 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Venkatesh Srinivas <venkateshs@...gle.com>,
        Lai Jiangshan <jiangshanlai+lkml@...il.com>
Subject: Re: [PATCH 2/2] KVM: Guard cpusmask NULL check with
 CONFIG_CPUMASK_OFFSTACK

Sean Christopherson <seanjc@...gle.com> writes:

> On Wed, Aug 25, 2021, Lai Jiangshan wrote:
>> On Sat, Aug 21, 2021 at 8:09 AM Sean Christopherson <seanjc@...gle.com> wrote:
>> > @@ -277,6 +277,14 @@ bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
>> >                 if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu))
>> >                         continue;
>> >
>> > +               /*
>> > +                * tmp can be NULL if cpumasks are allocated off stack, as
>> > +                * allocation of the mask is deliberately not fatal and is
>> > +                * handled by falling back to kicking all online CPUs.
>> > +                */
>> > +               if (IS_ENABLED(CONFIG_CPUMASK_OFFSTACK) && !tmp)
>> > +                       continue;
>> > +
>> 
>> Hello, Sean
>> 
>> I don't think it is a good idea to reinvent the cpumask_available().
>
> Using cpumask_available() is waaaay better, thanks!
>
> Vitaly / Paolo, take this one instead?
>

Sure, putting this to my v3, thanks!

-- 
Vitaly