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Subject: Re: [PATCH v2 005/118] NFSD: Replace the internals of the READ_BUF()
 macro
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <20201123191840.GH32599@fieldses.org>
Date:   Mon, 23 Nov 2020 14:21:02 -0500
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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References: <160590425404.1340.8850646771948736468.stgit@klimt.1015granger.net>
 <160590445271.1340.9408337302317384948.stgit@klimt.1015granger.net>
 <20201123191840.GH32599@fieldses.org>
To:     Bruce Fields <bfields@fieldses.org>
Precedence: bulk


> On Nov 23, 2020, at 2:18 PM, bfields@fieldses.org wrote:
>=20
> On Fri, Nov 20, 2020 at 03:34:12PM -0500, Chuck Lever wrote:
>> @@ -396,7 +281,7 @@ nfsd4_decode_fattr(struct nfsd4_compoundargs =
*argp, u32 *bmval,
>> 		READ_BUF(4); len +=3D 4;
>> 		nace =3D be32_to_cpup(p++);
>>=20
>> -		if (nace > compoundargs_bytes_left(argp)/20)
>> +		if (nace > xdr_stream_remaining(argp->xdr) / =
sizeof(struct nfs4_ace))
>=20
> Picky C question: is the compiler guaranteed to pack that struct in =
the
> obvious way?
>=20
> That aside, I'm not comfortable assuming the struct could never change
> to, say, include something that's useful during processing but doesn't
> appear on the wire.

OK, but you also don't like naked integers without documentation.
I can leave this as "xdr_stream_remaining() / 20" if you prefer.
Or we could define a macro somewhere that makes this code a little
more self-documenting.


> Also, that change isn't actually logically related to the rest of the
> patch, so it's the sort of thing I'd expect separated out.
>=20
> --b.

--
Chuck Lever