LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org, 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 21:38:10 +0100	[thread overview]
Message-ID: <20081030203810.GM27407@elte.hu> (raw)
In-Reply-To: <20081030133228.824e3f69.akpm@linux-foundation.org>


* Andrew Morton <akpm@linux-foundation.org> wrote:

> > +	/* make sure NMIs see the cleared bit */
> > +	smp_mb();
> > +
> > +	wait_for_nmi();
> > +
> > +	return mod_code_status;
> > +}
> 
> I guess the weakness here is that the code will only allow a single 
> contiguous hunk of text to be modified.  One could envisage 
> situations where two or more separate areas of memory need to be 
> modified atomically/together.
> 
> I guess we can cross that bridge when we fall off it.

yeah - the whole 'transaction' concept can be extended easily, in just 
one place.

Not that i think that it would really be useful to go beyond the 
current (target,len) abstraction - the less complex code patching is 
done, the better.

	Ingo

  reply	other threads:[~2008-10-30 20:38 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 [this message]
2008-10-30 20:58     ` Steven Rostedt
2008-10-30 21:10       ` Andrew Morton
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=20081030203810.GM27407@elte.hu \
    --to=mingo@elte.hu \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --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).