From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>
Subject: Re: [PATCH] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook
Date: Tue, 11 Feb 2020 16:31:24 +0100 [thread overview]
Message-ID: <20200211153124.GV14914@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200211150615.GK2935@paulmck-ThinkPad-P72>
On Tue, Feb 11, 2020 at 07:06:15AM -0800, Paul E. McKenney wrote:
> And I have to ask... What happens if we are very early in from-idle
> NMI entry (or very late in NMI exit), such that both in_nmi() and
> rcu_is_watching() are returning false? Or did I miss a turn somewhere?
We must, by very careful inspection, ensure that doesn't happen.
No tracing must happen before preempt_count increment / after
preempt_count decrement. Otherwise we can no longer recover.
next prev parent reply other threads:[~2020-02-11 15:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 22:06 [PATCH] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook Steven Rostedt
2020-02-11 0:30 ` Mathieu Desnoyers
2020-02-11 2:22 ` Steven Rostedt
2020-02-11 2:32 ` joel
2020-02-11 15:19 ` Mathieu Desnoyers
2020-02-11 12:00 ` Peter Zijlstra
2020-02-11 13:03 ` Paul E. McKenney
2020-02-11 13:16 ` Peter Zijlstra
2020-02-11 13:23 ` Paul E. McKenney
2020-02-11 14:10 ` Steven Rostedt
2020-02-11 11:49 ` Peter Zijlstra
2020-02-11 12:59 ` Paul E. McKenney
2020-02-11 13:10 ` Peter Zijlstra
2020-02-11 13:20 ` Paul E. McKenney
2020-02-11 14:05 ` Steven Rostedt
2020-02-11 15:05 ` Peter Zijlstra
2020-02-11 15:29 ` Peter Zijlstra
2020-02-11 16:16 ` Steven Rostedt
2020-02-11 15:06 ` Paul E. McKenney
2020-02-11 15:31 ` Peter Zijlstra [this message]
2020-02-11 15:40 ` Paul E. McKenney
2020-02-11 12:21 ` Peter Zijlstra
2020-02-11 14:10 ` Steven Rostedt
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