Re: [PATCH for-next 5/8] IB/core: Use __be32 for LIDs in opa_is_extended_lid

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Tue, Oct 03, 2017 at 05:05:06PM +0000, Hefty, Sean wrote:
> > > > >  	if ((be32_to_cpu(dlid) >=
> > > > >  	     be16_to_cpu(IB_MULTICAST_LID_BASE)) ||
> > > > >  	    (be32_to_cpu(slid) >=
> > > > >  	     be16_to_cpu(IB_MULTICAST_LID_BASE)))
> > > >
> > > > You can drop be32_to_cpu and be16_to_cpu now.
> > > > The dlid is __be32 and IB_MULTICAST_LID_BASE is __be16. The direct
> > > > comparison will work.
> > >
> > > It won't order properly for >=, the swap is still needed...
> >
> > Jason,
> > Do you have reference for that?
> >
> > I tried to find any information about comparison of values from one
> > endianess on machine with another endianess and didn't find anything
> > relevant.
>
> The bytes are out of order, so the comparisons won't work.

I understand it for the "manual" comparison (C-like arrays), but does it apply
for the compiler-aware comparison? Both these variables are marked as
__be32 for the compiler.

Thanks

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