RE: [PATCH] Drivers: hv: vmbus: Return -EINVAL for the sys files for unopened channels

[Dexuan Cui]

> From: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
> Sent: Monday, December 17, 2018 10:17 AM
> To: Dexuan Cui <decui@xxxxxxxxxxxxx>
> 
> On Mon, 17 Dec 2018 18:00:29 +0000
> Dexuan Cui <decui@xxxxxxxxxxxxx> wrote:
> 
> > > From: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
> > > On Thu, 13 Dec 2018 16:35:43 +0000
> > > Dexuan Cui <decui@xxxxxxxxxxxxx> 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 way. :-)
> >
> > But, yes, I agree with you that generally we should make a common
> > function to avoid duplicate code.
> >
> > Thanks,
> > -- Dexuan
> 
> 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