From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steve French <smfrench@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Steve French <sfrench@samba.org>,
CIFS <linux-cifs@vger.kernel.org>,
samba-technical <samba-technical@lists.samba.org>,
LKML <linux-kernel@vger.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [PATCH 1/2] cifs: remove unused status severity defines
Date: Thu, 14 Mar 2019 16:39:54 +0900 [thread overview]
Message-ID: <20190314073954.GA5272@jagdpanzerIV> (raw)
In-Reply-To: <CAH2r5ms3sdFx864M4se0V1eCAj_x8_3xyyRxoxqS52_UQNNjaA@mail.gmail.com>
On (03/14/19 02:19), Steve French wrote:
> All of those uses of __constant_cpu_to_le32 apparently (at least
> according to checkpatch) should be changed (someday) to cpu_to_le32
> but I didn't research why the change from __constant_cpu_to_le32
> ---> cpu_to_le32
Probably historic reasons.
Looking at linux 2.4.21
/*
* Allow constant folding
*/
#if defined(__GNUC__) && (__GNUC__ >= 2) && defined(__OPTIMIZE__)
# define __swahw32(x) \
(__builtin_constant_p((__u32)(x)) ? \
___swahw32((x)) : \
__fswahw32((x)))
My assumption would be that __GNUC__ < 2 did no support
__builtin_constant_p?
> If it has benefit - and checkpatch is right (it warned about
> __constant_cpu_to_le32 being no longer preferred) ... perhaps would be
> worth a followup patch to clean the rest of them up? If you have any
> context on why kernel code has moved away from using the older format
> of __constant_cpu_to_.... would be useful to know if any benefit to
> the change
Right, that's what I'm going to do - send out patches and update the rest
of __constant_cpu_to_XX users; so, eventually, __constant_cpu_to_XX
can be removed.
-ss
next prev parent reply other threads:[~2019-03-14 7:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-14 6:17 [PATCH 1/2] cifs: remove unused status severity defines Sergey Senozhatsky
2019-03-14 6:54 ` Steve French
2019-03-14 7:04 ` Steve French
2019-03-14 7:12 ` Sergey Senozhatsky
2019-03-14 7:19 ` Steve French
2019-03-14 7:39 ` Sergey Senozhatsky [this message]
2019-03-14 8:03 ` Steve French
2019-03-14 7:08 ` Sergey Senozhatsky
[not found] ` <20190314061716.19892-2-sergey.senozhatsky@gmail.com>
2019-03-15 12:31 ` [PATCH 2/2] cifs: don't use __constant_cpu_to_le32() David Laight
2019-03-15 14:29 ` Sergey Senozhatsky
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