> On Feb 4, 2019, at 9:32 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> On Mon, Feb 04, 2019 at 09:16:54AM -0500, Chuck Lever wrote:
>> They are. The problem is that we are byte-swapping the incoming wire
>> data and then comparing to CPU-endian constants in some hot paths.
>> It's better to leave the incoming data alone and compare to a pre-
>> byte-swapped constant. This patch adds some of these constants that
>> were missing, in preparation for fixing the hot paths.
>>
>> That is apparently not clear from the patch description, so I will
>> endeavor to improve it.
>
> Why do we need new enums / #defines for that?
>
> Just replace:
>
> if (beXX_to_cpu(pkt->field) == SOME_CONSTANT)
>
> with
>
> if (pkt->field == cpu_to_be32(SOME_CONSTANT))
>
> and we are done.
True.
> The latter is a pretty common pattern through the kernel.
However the pattern in the NFS server and lockd is to define a
lower-case version of the same macro that is pre-byte-swapped.
I'm attempting to follow existing precedent in this area.
We already have, for example, in various sunrpc headers:
enum rpc_accept_stat {
RPC_SUCCESS = 0,
RPC_PROG_UNAVAIL = 1,
RPC_PROG_MISMATCH = 2,
...
};
#define rpc_success cpu_to_be32(RPC_SUCCESS)
#define rpc_prog_unavail cpu_to_be32(RPC_PROG_UNAVAIL)
#define rpc_prog_mismatch cpu_to_be32(RPC_PROG_MISMATCH)
Or, for NFS:
enum nfs_stat {
...
NFSERR_SHARE_DENIED = 10015,
...
};
#define nfserr_share_denied cpu_to_be32(NFSERR_SHARE_DENIED)
There are some missing lower-case macros, which I am trying to
add to our existing collection before I rewrite the RPC header
encoding and decoding functions. So I'm adding:
+ rpc_gss_version = cpu_to_be32(RPC_GSS_VERSION),
+ rpc_call = cpu_to_be32(RPC_CALL),
+ rpc_reply = cpu_to_be32(RPC_REPLY),
+
+ rpc_msg_accepted = cpu_to_be32(RPC_MSG_ACCEPTED),
+ rpc_msg_denied = cpu_to_be32(RPC_MSG_DENIED),
Actually since we have decided not to use enum for these, this
smaller addition can simply be squashed into the later patches,
and I can drop this patch, which was intended as a clean-up but
now appears to be unnecessary.
--
Chuck Lever
