From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>, Qian Cai <cai@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>, x86 <x86@kernel.org>,
linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
Linux Next Mailing List <linux-next@vger.kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [tip: locking/core] lockdep: Fix lockdep recursion
Date: Thu, 15 Oct 2020 11:50:33 +0200 [thread overview]
Message-ID: <20201015095033.GS2651@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201015094926.GY2611@hirez.programming.kicks-ass.net>
On Thu, Oct 15, 2020 at 11:49:26AM +0200, Peter Zijlstra wrote:
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1143,13 +1143,15 @@ bool rcu_lockdep_current_cpu_online(void
> struct rcu_data *rdp;
> struct rcu_node *rnp;
> bool ret = false;
> + unsigned long seq;
>
> if (in_nmi() || !rcu_scheduler_fully_active)
> return true;
> preempt_disable_notrace();
> rdp = this_cpu_ptr(&rcu_data);
> rnp = rdp->mynode;
> - if (rdp->grpmask & rcu_rnp_online_cpus(rnp))
> + seq = READ_ONCE(rnp->ofl_seq) & ~0x1;
> + if (rdp->grpmask & rcu_rnp_online_cpus(rnp) || seq != READ_ONCE(rnp->ofl_seq))
> ret = true;
> preempt_enable_notrace();
> return ret;
Also, here, are the two loads important? Wouldn't:
|| READ_ONCE(rnp->ofl_seq) & 0x1
be sufficient?
next prev parent reply other threads:[~2020-10-15 9:50 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <160223032121.7002.1269740091547117869.tip-bot2@tip-bot2>
2020-10-09 13:41 ` [tip: locking/core] lockdep: Fix lockdep recursion Qian Cai
2020-10-09 13:58 ` Paul E. McKenney
2020-10-09 15:30 ` Qian Cai
2020-10-09 16:11 ` Paul E. McKenney
2020-10-09 16:23 ` Peter Zijlstra
2020-10-09 16:37 ` Paul E. McKenney
2020-10-09 17:36 ` Qian Cai
2020-10-09 17:50 ` Paul E. McKenney
2020-10-09 17:54 ` Qian Cai
2020-10-09 18:21 ` Paul E. McKenney
2020-10-12 3:11 ` Boqun Feng
2020-10-12 14:14 ` Qian Cai
2020-10-12 21:28 ` Paul E. McKenney
2020-10-13 10:34 ` Peter Zijlstra
2020-10-13 10:44 ` Peter Zijlstra
2020-10-13 11:25 ` Peter Zijlstra
2020-10-13 16:26 ` Paul E. McKenney
2020-10-13 19:30 ` Paul E. McKenney
2020-10-14 18:34 ` Paul E. McKenney
2020-10-14 21:53 ` Peter Zijlstra
2020-10-14 22:11 ` Paul E. McKenney
2020-10-14 22:39 ` Peter Zijlstra
2020-10-14 23:55 ` Paul E. McKenney
2020-10-15 3:41 ` Paul E. McKenney
2020-10-15 9:49 ` Peter Zijlstra
2020-10-15 9:50 ` Peter Zijlstra [this message]
2020-10-15 16:15 ` Paul E. McKenney
2020-10-15 9:52 ` Peter Zijlstra
2020-10-15 16:20 ` Paul E. McKenney
2020-10-15 16:15 ` Paul E. McKenney
2020-10-15 17:23 ` Paul E. McKenney
2020-10-13 16:15 ` Paul E. McKenney
2020-10-13 10:27 ` Peter Zijlstra
2020-10-13 16:24 ` Boqun Feng
2020-10-27 19:31 ` Qian Cai
2020-10-28 3:01 ` Paul E. McKenney
2020-10-28 14:39 ` Qian Cai
2020-10-28 15:53 ` Paul E. McKenney
2020-10-28 20:08 ` Qian Cai
2020-10-28 21:02 ` 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=20201015095033.GS2651@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=boqun.feng@gmail.com \
--cc=cai@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-next@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=paulmck@kernel.org \
--cc=rostedt@goodmis.org \
--cc=sfr@canb.auug.org.au \
--cc=x86@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox