From: Christoph Hellwig <hch@infradead.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Guo Ren <guoren@kernel.org>, Guenter Roeck <linux@roeck-us.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-csky@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>,
Guo Ren <guoren@linux.alibaba.com>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] csky: uaccess.h: Coding convention with asm generic
Date: Wed, 28 Apr 2021 13:49:46 +0100 [thread overview]
Message-ID: <20210428124946.GA1976154@infradead.org> (raw)
In-Reply-To: <CAK8P3a1DvsXSEDoovLk11hzNHyJi7vqNoToU+n5aFi2viZO_Uw@mail.gmail.com>
On Wed, Apr 28, 2021 at 11:25:29AM +0200, Arnd Bergmann wrote:
> Actually, please don't use the asm-generic __put_user version based
> on copy_to_user, we probably have killed it off long ago.
Yes, they are horrible.
> We might want to come up with a new version of asm-generic/uaccess.h
> that actually makes it easier to have a sane per-architecture
> implementation of the low-level accessors without set_fs().
>
> I've added Christoph to Cc here, he probably has some ideas
> on where we should be heading.
I think asm-generic/uaccess.h pretty much only makes sense for
nommu. For that case we can just kill the __{get,put}_user_fn
indirection. I actually have work for that in an old branch.
Trying to use any of asm-generic/uaccess.h for MMU based kernel is
just asking for trouble.
> One noteworthy aspect is that almost nothing users the low-level
> __get_user()/__put_user() helpers any more outside of architecture
> specific code, so we may not need to have separate versions
> for much longer.
Al has been trying to kill them off entirely for a while, and I hope
he'll eventually succeed. That being said the difference should be
that the __ versions just skip the access_ok, so having both is
fairly trivial to implement.
next prev parent reply other threads:[~2021-04-28 12:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 8:54 [PATCH] csky: uaccess.h: Coding convention with asm generic guoren
2021-04-21 14:48 ` Christoph Hellwig
2021-04-28 3:18 ` Guenter Roeck
2021-04-28 8:29 ` Guo Ren
2021-04-28 9:25 ` Arnd Bergmann
2021-04-28 12:49 ` Christoph Hellwig [this message]
2021-04-28 13:07 ` Guo Ren
2021-04-28 13:48 ` Arnd Bergmann
2021-04-28 13:03 ` Guo Ren
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