linux-kernel - Re: [PATCH v6 14/22] KVM: Clean up local variable usage in __kvm_set_memory

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Message-ID: <1467b8cd-3631-b5da-b285-dbdf31b75af7@redhat.com>
Date:   Fri, 21 Feb 2020 18:43:34 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-mips@...r.kernel.org, kvm@...r.kernel.org,
        kvm-ppc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Christoffer Dall <christoffer.dall@....com>,
        Peter Xu <peterx@...hat.com>,
        Philippe Mathieu-Daudé <f4bug@...at.org>
Subject: Re: [PATCH v6 14/22] KVM: Clean up local variable usage in
 __kvm_set_memory_region()

On 18/02/20 22:07, Sean Christopherson wrote:
> -sorted by update_memslots(), and the old
>  	 * memslot needs to be referenced after calling update_memslots(), e.g.
> -	 * to free its resources and for arch specific behavior.
> +	 * to free its resources and for arch specific behavior.  Kill @tmp
> +	 * after making a copy to deter potentially dangerous usage.
>  	 */
> -	old = *slot;
> +	tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
> +	old = *tmp;
> +	tmp = NULL;
> +

Also: old = *id_to_memslot(...).

Paolo