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Message-ID: <20140228155130.26adcef3@gandalf.local.home>
Date: Fri, 28 Feb 2014 15:51:30 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: "H. Peter Anvin" <hpa@...or.com>,
Vince Weaver <vincent.weaver@...ne.edu>,
Linux Kernel <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...hat.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Subject: Re: [PATCH] x86: Rename copy_from_user_nmi() to
copy_from_user_trace()
On Fri, 28 Feb 2014 21:46:21 +0100
Peter Zijlstra <peterz@...radead.org> wrote:
> On Fri, Feb 28, 2014 at 02:33:16PM -0500, Steven Rostedt wrote:
> > [ H. Peter, Here's the rename patch. I did not include your update. You
> > can add that first and then massage this patch on top. But this isn't
> > critical for mainline or stable, where as I believe your patch is. ]
> >
> > The tracing utilities sometimes need to read from userspace (stack tracing),
> > and to do this it has as special copy_from_user function called
> > copy_from_user_nmi(). Well, as tracers can call this from outside of
> > nmi context, the "_nmi" part is a misnomer and "_trace" is a better
> > name.
>
> NAK, spin_lock_irq() is very much an IRQ safe lock. Similarly
> copy_from_user_nmi() is an NMI safe copy from user.
>
> Furthermore, there's exactly 0 trace users, so the proposed name is
> actively worse.
Heh, I consider perf and oprofile special tracers ;-)
-- Steve
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