From: Tejun Heo <tj@kernel.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH RFC] stop_machine: make stop_machine safe and efficient to call early
Date: Fri, 30 Sep 2011 16:06:35 -0700 [thread overview]
Message-ID: <20110930230635.GA2658@mtj.dyndns.org> (raw)
In-Reply-To: <4E85EE1F.7050508@goop.org>
Hello, Jeremy.
On Fri, Sep 30, 2011 at 09:28:15AM -0700, Jeremy Fitzhardinge wrote:
> Make stop_machine() safe to call early in boot, before SMP has been
> set up, by simply calling the callback function directly if there's
> only one CPU online.
...
> @@ -485,6 +485,9 @@ int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
> .num_threads = num_online_cpus(),
> .active_cpus = cpus };
>
> + if (smdata.num_threads == 1)
> + return (*fn)(data);
> +
As others have pointed out, you'll need to call both local and hardirq
disables. Also, I think the description and the code are a bit
misleading. How aobut setting cpu_stop_initialized in cpu_stop_init()
and testing it from __stop_machine() instead? I think it would be
better to keep the behavior as uniform as possible once things are up
and running.
Thank you.
--
tejun
next prev parent reply other threads:[~2011-09-30 23:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 16:28 Jeremy Fitzhardinge
2011-09-30 16:34 ` Steven Rostedt
2011-09-30 17:00 ` Jeremy Fitzhardinge
2011-09-30 21:06 ` Andrew Morton
2011-09-30 21:21 ` Steven Rostedt
2011-09-30 21:23 ` Andrew Morton
2011-09-30 23:06 ` Tejun Heo [this message]
2011-09-30 23:32 ` Jeremy Fitzhardinge
2011-09-30 23:39 ` Tejun Heo
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=20110930230635.GA2658@mtj.dyndns.org \
--to=tj@kernel.org \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=hpa@zytor.com \
--cc=jeremy@goop.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=rostedt@goodmis.org \
--cc=rusty@rustcorp.com.au \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®