Re: [dpdk-dev] [PATCH 3/3] ethdev: fix build warning on 64-bit value

[Thomas Monjalon <thomas@monjalon.net>]

27/04/2020 16:00, David Marchand:
> On Mon, Apr 27, 2020 at 3:47 PM Ananyev, Konstantin wrote:
> > From: dev <dev-bounces@dpdk.org> On Behalf Of David Marchand
> > > On Mon, Apr 27, 2020 at 3:34 PM Bruce Richardson
> > > <bruce.richardson@intel.com> wrote:
> > > > On Mon, Apr 27, 2020 at 03:23:41PM +0200, David Marchand wrote:
> > > > > Building OVS with dpdk, sparse complains about 64-bit constant being
> > > > > passed as a normal integer that can't fit it:
> > > > > error: constant 0xffffffffffffffff is so big it is unsigned long
> > > > >
> > > > > Fixes: ecbc8570131d ("ethdev: add PFCP header to flow API")
> > > > >
> > > > > Signed-off-by: David Marchand <david.marchand@redhat.com>
> > > > > ---
> > > > > --- a/lib/librte_ethdev/rte_flow.h
> > > > > +++ b/lib/librte_ethdev/rte_flow.h
> > > > >  static const struct rte_flow_item_pfcp rte_flow_item_pfcp_mask = {
> > > > >       .s_field = 0x01,
> > > > > -     .seid = RTE_BE64(0xffffffffffffffff),
> > > > > +     .seid = RTE_BE64(UINT64_C(0xffffffffffffffff)),
> > > >
> > > > Rather than cast, why not put "ULL" at the end. If we are going to cast,
> > > > why not just put "-1" in to save some digits.
> > >
> > > I preferred this form in the hope future developers who want
> > > 0x0fffffffffffffff will copy/paste this.
> > >
> >
> > As I remember there should be UINT64_MAX in stdint.h.
> 
> Yes, we could go with:
> +     .seid = RTE_BE64(UINT64_MAX),
> 
> And then next time, for any value like 0x0fff ffff ffff ffff (had to
> group the digits of what I had written), pretty sure we will miss this
> and I will catch it only when building ovs.

I agree with David (in general and especially here).

RTE_BE64 is required for static analyzers and is an explicit info.

UINT64_C is better than ULL suffix because it
	- is generic
	- gives size explicitly

UINT64_C(0xffffffffffffffff) is better than UINT64_MAX because
	- rte_flow.h has a lot of bitmasks
	- it is copy/paste safe

Acked-by: Thomas Monjalon <thomas@monjalon.net>