LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Andrew Morton <akpm@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de,
	peterz@infradead.org, torvalds@linux-foundation.org,
	srostedt@redhat.com
Subject: Re: [PATCH 1/2] ftrace: nmi safe code modification
Date: Thu, 30 Oct 2008 14:10:48 -0700	[thread overview]
Message-ID: <20081030141048.904c82e1.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.DEB.1.10.0810301645100.21031@gandalf.stny.rr.com>

On Thu, 30 Oct 2008 16:58:55 -0400 (EDT)
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 30 Oct 2008, Andrew Morton wrote:
> > 
> > > +#ifndef __ASSEMBLY__
> > > +#define ftrace_nmi_enter()	do { } while (0)
> > > +#define ftrace_nmi_exit()	do { } while (0)
> > > +#endif
> > > ...
> > > +#ifndef __ASSEMBLY__
> > > +#define ftrace_nmi_enter()	do { } while (0)
> > > +#define ftrace_nmi_exit()	do { } while (0)
> > > +#endif
> > 
> > These could all be written in C.  If there's a reson to write them in
> > cpp then the `#ifndef __ASSEMBLY__' isn't really needed.
> 
> I could do the C macro, and you are right, I did not need the __ASSEMBLY__ 
> part. I guess that was me just being over-protective :-/
> 
> Which would you prefer?  Changing to C or removing the __ASSEMBLY__?

>From a general perspective, C is better.  Has typechecking, adds a ref
to the arguments which can prevent unused-var warnings, easier to read
and maintain, more likely to be commented, known about by debug info,
doesn't all get clumped into a single line in debug info, easier/safer
to uninline, blah, blah.

Also it seems a bit weird to do

#ifdef SOMETHING
#define foo(...) ...
#else
extern void foo(...);
#endif

Doing it in C has the downside that more things need to be visible at
the definition site, so more includes might be needed.  Often fixable
by uninlining.


I dunno.  People seem to instinctively reach for a macro without
thinking, because that's how grandpa did it or something.


  reply	other threads:[~2008-10-30 21:12 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-30 20:08 [PATCH 0/2] ftrace: handle NMIs safely Steven Rostedt
2008-10-30 20:08 ` [PATCH 1/2] ftrace: nmi safe code modification Steven Rostedt
2008-10-30 20:32   ` Andrew Morton
2008-10-30 20:38     ` Ingo Molnar
2008-10-30 20:58     ` Steven Rostedt
2008-10-30 21:10       ` Andrew Morton [this message]
2008-10-31  4:03         ` [PATCH] ftrace: nmi safe code clean ups Steven Rostedt
2008-10-31  4:16           ` [PATCH] hardirq.h clean up Steven Rostedt
2008-10-31  9:30             ` Ingo Molnar
2008-10-31 13:36               ` [PATCH] ftrace: fix hardirq header for non ftrace archs Steven Rostedt
2008-11-03 10:04                 ` Ingo Molnar
2008-10-31  9:28           ` [PATCH] ftrace: nmi safe code clean ups Ingo Molnar
2008-10-30 20:08 ` [PATCH 2/2] ftrace: nmi update statistics Steven Rostedt
2008-10-30 20:38   ` Andrew Morton
2008-10-30 21:14     ` Steven Rostedt
2008-10-30 20:34 ` [PATCH 0/2] ftrace: handle NMIs safely Ingo Molnar
2008-10-30 21:15   ` Steven Rostedt
2008-10-30 22:26     ` Ingo Molnar

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20081030141048.904c82e1.akpm@linux-foundation.org \
    --to=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=srostedt@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: [PATCH 1/2] ftrace: nmi safe code modification' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).