From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: Quick review of -rt RCU-related patches
Date: Wed, 05 Oct 2011 00:12:35 +0200 [thread overview]
Message-ID: <1317766355.32543.38.camel@twins> (raw)
In-Reply-To: <alpine.LFD.2.02.1110042322450.18778@ionos>
On Wed, 2011-10-05 at 00:05 +0200, Thomas Gleixner wrote:
> > peter_zijlstra-frob-rcu.patch
> >
> > Looks OK. Hmmm... Should this one go to mainline?
> > Oh, looks equivalent, actually. So why the change?
>
> Peter ?
- if (in_irq() || in_serving_softirq()) {
+ if (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_OFFSET)) {
For !rt its equivalent yes, for rt otoh its not:
int in_serving_softirq(void)
{
int res;
preempt_disable();
res = __get_cpu_var(local_softirq_runner) == current;
preempt_enable();
return res;
}
However invoke_softirq() will still add SOFTIRQ_OFFSET so we need to
look at that to avoid recursion issues.
The changelog describes this. So this change is a direct consequence of
-rt frobbing the softirq stuff and thus isn't needed upstream.
next prev parent reply other threads:[~2011-10-04 22:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-04 17:47 Quick review of -rt RCU-related patches Paul E. McKenney
2011-10-04 22:05 ` Thomas Gleixner
2011-10-04 22:12 ` Peter Zijlstra [this message]
2011-10-04 23:15 ` Paul E. McKenney
2011-10-04 22:13 ` Peter Zijlstra
2011-10-04 23:15 ` Paul E. McKenney
2011-10-04 23:27 ` Thomas Gleixner
2011-10-04 23:56 ` Paul E. McKenney
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=1317766355.32543.38.camel@twins \
--to=peterz@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=tglx@linutronix.de \
/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