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
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