linux-kernel - Re: [PATCH v5 13/32] x86/boot/e820: Add support to determine the E820 type of an address

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Message-ID: <CAKv+Gu-h+1UWPCUwvJT2AD=JtPqYQRRrrUCFjWNiAOCKfHh7rg@mail.gmail.com>
Date:   Sat, 6 May 2017 08:48:22 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        KVM devel mailing list <kvm@...r.kernel.org>,
        linux-doc@...r.kernel.org, "x86@...nel.org" <x86@...nel.org>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        iommu@...ts.linux-foundation.org, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v5 13/32] x86/boot/e820: Add support to determine the E820
 type of an address

On 5 May 2017 at 18:11, Borislav Petkov <bp@...en8.de> wrote:
> On Tue, Apr 18, 2017 at 04:18:31PM -0500, Tom Lendacky wrote:
>> Add a function that will return the E820 type associated with an address
>> range.
>
> ...
>
>> @@ -110,9 +111,28 @@ bool __init e820__mapped_all(u64 start, u64 end, enum e820_type type)
>>                * coverage of the desired range exists:
>>                */
>>               if (start >= end)
>> -                     return 1;
>> +                     return entry;
>>       }
>> -     return 0;
>> +
>> +     return NULL;
>> +}
>> +
>> +/*
>> + * This function checks if the entire range <start,end> is mapped with type.
>> + */
>> +bool __init e820__mapped_all(u64 start, u64 end, enum e820_type type)
>> +{
>> +     return __e820__mapped_all(start, end, type) ? 1 : 0;
>
>         return !!__e820__mapped_all(start, end, type);
>

Even the !! double negation is redundant, given that the function returns bool.