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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     "Michael Kelley \(EOSG\)" <Michael.H.Kelley@microsoft.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        kbuild test robot <lkp@intel.com>,
        "kbuild-all\@01.org" <kbuild-all@01.org>,
        "kvm\@vger.kernel.org" <kvm@vger.kernel.org>,
        "x86\@kernel.org" <x86@kernel.org>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devel\@linuxdriverproject.org" <devel@linuxdriverproject.org>,
        Ingo Molnar <mingo@redhat.com>,
        Roman Kagan <rkagan@virtuozzo.com>,
        Andy Lutomirski <luto@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Mohammed Gamal <mmorsy@redhat.com>
Subject: Re: [PATCH v3 3/7] x86/hyper-v: reenlightenment notifications support
References: <20180116182700.1042-4-vkuznets@redhat.com>
        <201801191841.QZ26OYif%fengguang.wu@intel.com>
        <87o9lqdt15.fsf@vitty.brq.redhat.com>
        <alpine.DEB.2.20.1801200846210.1998@nanos>
        <DM5PR2101MB10309A7D99F89B5AD8AB1343DCEC0@DM5PR2101MB1030.namprd21.prod.outlook.com>
        <877esacd24.fsf@vitty.brq.redhat.com>
        <87d120bslq.fsf@vitty.brq.redhat.com>
        <DM5PR2101MB10301FFABF7ACA1C391A0F27DCE30@DM5PR2101MB1030.namprd21.prod.outlook.com>
Date:   Tue, 23 Jan 2018 15:07:44 +0100
In-Reply-To: <DM5PR2101MB10301FFABF7ACA1C391A0F27DCE30@DM5PR2101MB1030.namprd21.prod.outlook.com>
        (Michael Kelley's message of "Tue, 23 Jan 2018 14:02:07 +0000")
Message-ID: <877es8brdb.fsf@vitty.brq.redhat.com>
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"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com> writes:

> Vitaly Kuznetsov <vkuznets@redhat.com> writes:
>> 
>> > "Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com> writes:
>> >
>> >> On Fri, 19 Jan 2018, Thomas Gleixner wrote:
>> >>
>> >>>
>> >>> You added '#include <linux/interrupt.h>' to mshyperv.h which is included in
>> >>> vclock_gettime.c and pulls in other stuff which fails to expand....
>> >>
>> >> Is the declaration of hyperv_reenlightenment_intr() even needed in
>> >> mshyperv.h?  The '#include <linux/interrupt.h>' is there for the __irq_entry
>> >> annotation on that declaration.   There's a declaration of the parallel (and
>> >> unannotated) hyperv_vector_handler(), but that looks like a fossil that
>> >> isn't needed either.
>> >>
>> >
>> > True,
>> >
>> > the only need for the declaration in mshyperv.h is to silence "warning:
>> > no previous prototype for ‘hyperv_reenlightenment_intr’"; I'm not sure
>> > if this actually needs fixing.
>> 
>> It seems we can get away with dropping '__visible' and '__irq_entry'
>> qualifiers from 'hyperv_reenlightenment_intr' declaration in mshyperv.h
>> while keeping them in hv_init.c for the implementation. This way we can
>> avoid the nasty 'no previous prototype' warning and not have to add
>> '#include <linux/interrupt.h>' to mshyperv.h breaking vdso.
>
> Where exactly is the 'no previous prototype' warning being generated?

It is generated while compiling the implementation in hv_init.c, every
non-static function needs a previously defined prototype.

-- 
  Vitaly