From: "Paul E. McKenney" <paulmck@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
Boqun Feng <boqun.feng@gmail.com>,
linux-kernel@vger.kernel.org,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
rcu@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH V2 2/7] rcu: cleanup rcu_preempt_deferred_qs()
Date: Tue, 18 Feb 2020 08:43:14 -0800 [thread overview]
Message-ID: <20200218164314.GG2935@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20200218094124.339c0315@gandalf.local.home>
On Tue, Feb 18, 2020 at 09:41:24AM -0500, Steven Rostedt wrote:
> On Mon, 17 Feb 2020 15:23:07 -0800
> "Paul E. McKenney" <paulmck@kernel.org> wrote:
>
> > > I'm still asking for more comments.
> > >
> > > By now, I have received some precious comments, mainly due to my
> > > stupid naming mistakes and a misleading changelog. I should have
>
> How about typos?
We appear to have enough typos, thank you!
> > > updated all these with a new series patches. But I hope I
> > > can polish more in the new patchset with more suggestions from
> > > valuable comments, especially in x86,scheduler,percpu and rcu
> > > areas.
> > >
> > > I'm very obliged to hear anything.
> >
> > commit 23a58acde0eea57ac77377e5d50d9562b2dbdfaa
> > Author: Lai Jiangshan <laijs@linux.alibaba.com>
> > Date: Sat Feb 15 14:37:26 2020 -0800
> >
> > rcu: Don't set nesting depth negative in rcu_preempt_deferred_qs()
> >
> > Now that RCU flavors have been consolidated, an RCU-preempt
> > rcu_rea_unlock() in an interrupt or softirq handler cannot possibly
>
> What's a "rea"? ;-)
A typo. Probably mine. Thank you for catching it, will fix! ;-)
But maybe an rcu_rhea_lock()? Just in case the rheas are getting loose?
Thanx, Paul
> -- Steve
>
> > end the RCU read-side critical section. Consider the old vulnerability
> > involving rcu_preempt_deferred_qs() being invoked within such a handler
> > that interrupted an extended RCU read-side critical section, in which
> > a wakeup might be invoked with a scheduler lock held. Because
> > rcu_read_unlock_special() no longer does wakeups in such situations,
> > it is no longer necessary for rcu_preempt_deferred_qs() to set the
> > nesting level negative.
> >
> > This commit therfore removes this recursion-protection code from
> > rcu_preempt_deferred_qs().
> >
> > Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> >
> >
next prev parent reply other threads:[~2020-02-18 16:43 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-02 12:45 [PATCH V2 0/7] rcu: introduce percpu rcu_preempt_depth Lai Jiangshan
2019-11-02 12:45 ` [PATCH V2 1/7] rcu: use preempt_count to test whether scheduler locks is held Lai Jiangshan
2019-11-15 16:53 ` Paul E. McKenney
2020-02-19 3:31 ` Joel Fernandes
2020-02-19 3:59 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 2/7] rcu: cleanup rcu_preempt_deferred_qs() Lai Jiangshan
2019-11-03 2:01 ` Boqun Feng
2019-11-03 5:01 ` Lai Jiangshan
2019-11-04 14:55 ` Paul E. McKenney
2019-11-05 2:09 ` Lai Jiangshan
2019-11-05 7:19 ` Paul E. McKenney
2019-11-11 14:32 ` Paul E. McKenney
2019-11-12 1:28 ` Lai Jiangshan
2020-02-17 23:23 ` Paul E. McKenney
2020-02-18 14:41 ` Steven Rostedt
2020-02-18 16:43 ` Paul E. McKenney [this message]
2019-11-15 16:55 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 3/7] rcu: remove useless special.b.deferred_qs Lai Jiangshan
2020-02-17 23:23 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 4/7] rcu: don't use negative ->rcu_read_lock_nesting Lai Jiangshan
2020-02-17 23:26 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 5/7] rcu: wrap usages of rcu_read_lock_nesting Lai Jiangshan
2019-11-15 22:25 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 6/7] rcu: clear the special.b.need_qs in rcu_note_context_switch() Lai Jiangshan
2019-11-16 15:46 ` Paul E. McKenney
2019-11-02 12:45 ` [PATCH V2 7/7] x86,rcu: use percpu rcu_preempt_depth Lai Jiangshan
2019-11-02 16:30 ` Borislav Petkov
2019-11-03 4:33 ` Lai Jiangshan
2019-11-04 9:25 ` Sebastian Andrzej Siewior
2019-11-04 11:41 ` Lai Jiangshan
2019-11-04 12:09 ` Sebastian Andrzej Siewior
2019-11-16 15:48 ` Paul E. McKenney
2019-11-18 2:02 ` Lai Jiangshan
2019-11-18 14:59 ` Paul E. McKenney
2019-11-19 1:59 ` Lai Jiangshan
2019-11-19 21:14 ` Paul E. McKenney
2019-11-20 2:47 ` Lai Jiangshan
2019-11-21 4:02 ` Paul E. McKenney
2019-11-02 15:05 ` [PATCH V2 0/7] rcu: introduce " 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=20200218164314.GG2935@paulmck-ThinkPad-P72 \
--to=paulmck@kernel.org \
--cc=bigeasy@linutronix.de \
--cc=boqun.feng@gmail.com \
--cc=bp@alien8.de \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=laijs@linux.alibaba.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=peterz@infradead.org \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.