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From:   Dexuan Cui <decui@microsoft.com>
To:     Stephen Hemminger <stephen@networkplumber.org>
CC:     "'gregkh@linuxfoundation.org'" <gregkh@linuxfoundation.org>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>,
        "'devel@linuxdriverproject.org'" <devel@linuxdriverproject.org>,
        "'olaf@aepfle.de'" <olaf@aepfle.de>,
        "'jasowang@redhat.com'" <jasowang@redhat.com>,
        Michael Kelley <mikelley@microsoft.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>,
        "'apw@canonical.com'" <apw@canonical.com>,
        vkuznets <vkuznets@redhat.com>
Subject: RE: [PATCH] Drivers: hv: vmbus: Return -EINVAL for the sys files for
 unopened channels
Thread-Topic: [PATCH] Drivers: hv: vmbus: Return -EINVAL for the sys files for
 unopened channels
Thread-Index: AdSSumYR+EFelO/iSCugbWbDq9Br5wDcbnsAAAFGcVAAAN72gAAAc6qA
Date:   Mon, 17 Dec 2018 18:31:15 +0000
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> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Monday, December 17, 2018 10:17 AM
> To: Dexuan Cui <decui@microsoft.com>
>=20
> On Mon, 17 Dec 2018 18:00:29 +0000
> Dexuan Cui <decui@microsoft.com> wrote:
>=20
> > > From: Stephen Hemminger <stephen@networkplumber.org>
> > > On Thu, 13 Dec 2018 16:35:43 +0000
> > > Dexuan Cui <decui@microsoft.com> wrote:
> > >
> > > > Before 98f4c651762c, we returned zeros for unopened channels.
> > > > With 98f4c651762c, we started to return random on-stack values.
> > > >
> > > > We'd better return -EINVAL instead.
> > >
> > > The concept looks fine, but maybe it would be simpler to move it into
> > > hv_ringbuffer_get_debuginfo and have it return an error code.
> > >
> > > Since so much of the code is repeated, I would probably make a
> > > macro which generates the code as well.
> > >
> > > Something like this:
> >
> > Thanks, Stephen! Now the patch has been in char-misc's char-misc-linus
> > branch, so IMO we may as well leave it as is (considering the code here=
 is
> > unlikely to be frqeuencly changed), and we have a smaller patch this wa=
y. :-)
> >
> > But, yes, I agree with you that generally we should make a common
> > function to avoid duplicate code.
> >
> > Thanks,
> > -- Dexuan
>=20
> The old code was risky because it would silently return stack garbage.
> Having an error check in get_debuginfo would eliminate that.

OK, then let me make another patch based on the latest char-misc-linus.

Thanks,
-- Dexuan