From: Arnd Bergmann <arnd@arndb.de>
To: Namhyung Kim <namhyung@gmail.com>
Subject: Re: [RFC PATCH 02/43] ptrace: cleanup ptrace_request()
Date: Fri, 27 Aug 2010 21:26:56 +0200
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Cc: Roland McGrath <roland@redhat.com>, Oleg Nesterov <oleg@redhat.com>,
        linux-kernel@vger.kernel.org
References: <1282902149-12991-1-git-send-email-namhyung@gmail.com> <201008271623.01761.arnd@arndb.de> <87sk20f2z4.fsf@NHK-XNOTE.i-did-not-set--mail-host-address--so-tickle-me>
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On Friday 27 August 2010 18:13:35 Namhyung Kim wrote:
> Arnd Bergmann <arnd@arndb.de> writes:
> > If you introduce two pointers, 'siginfo_t __user *usiginfo' and
> > 'unsigned long __user *datap' instead of just 'datap', you can use
> > get_user/put_user everywhere, which would make the code better readable
> > and faster.
> >
> > Otherwise this change looks good.
> >
> 
> Despite I don't know how much it can run faster, I just want to keep it as is
> unless it would be a serious mistake. :-)

No, not a mistake, your code is fine as it is and not performance
critical at all.

However, in general using get_user/put_user is preferred over
copy_from_user/copy_to_user for scalar values.

	Arnd
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