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Subject: RE: [PATCH v1] gpudev: return EINVAL if invalid input pointer for
 free and unregister
Date: Thu, 2 Dec 2021 14:56:08 +0100
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
 "Thomas Monjalon" <thomas@monjalon.net>,
 "Tyler Retzlaff" <roretzla@linux.microsoft.com>,
 "Richardson, Bruce" <bruce.richardson@intel.com>
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> From: Ananyev, Konstantin [mailto:konstantin.ananyev@intel.com]
> Sent: Thursday, 2 December 2021 14.01
>=20
> > > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > Sent: Thursday, 2 December 2021 08.19
> > >
> > > 01/12/2021 22:37, Tyler Retzlaff:
> > > > On Wed, Nov 24, 2021 at 06:04:56PM +0000, Bruce Richardson =
wrote:
> > > > >   if (ret < 0 && rte_errno =3D=3D EAGAIN)
> > > >
> > > > i only urge that this be explicit as opposed to a range i.e. ret
> =3D=3D -
> > > 1
> > > > preferred over ret < 0
> > >
> > > I don't understand why you think it is important to limit return
> value
> > > to -1.
> > > Why "if (ret =3D=3D -1)" is better than "if (ret < 0)" ?
> >
> > Speaking for myself:
> >
> > For clarity. It leaves no doubt that "it failed" is represented by
> the return value -1, and that the function does not return errno =
values
> such as
> > -EINVAL.
> >
>=20
> But why '< 0' gives you less clarity?
> Negative value means failure - seems perfectly clear to me.

I disagree: Negative value does not mean failure. Only -1 means failure.

There is no -2 return value. There is no -EINVAL return value.

Testing for (ret < 0) might confuse someone to think that other values =
than -1 could be returned as indication of failure, which is not the =
case when following the convention where the functions set errno and =
return -1 in case of failure.

It would be different if following a convention where the functions =
return -errno in case of failure. In this case, testing (ret < 0) would =
be appropriate.

So explicitly testing (ret =3D=3D -1) clarifies which of the two =
conventions are relevant.