linux-kernel - Re: [PATCH] printk: Make console tracepoint safe in NMI() context

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Date:   Fri, 15 Jul 2022 11:25:16 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Marco Elver <elver@...gle.com>, Petr Mladek <pmladek@...e.com>,
        John Ogness <john.ogness@...utronix.de>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        kasan-dev@...glegroups.com, Thomas Gleixner <tglx@...utronix.de>,
        Johannes Berg <johannes.berg@...el.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Functional Testing <lkft@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printk: Make console tracepoint safe in NMI() context

On Fri, 15 Jul 2022 08:10:00 -0700
"Paul E. McKenney" <paulmck@...nel.org> wrote:

> So if preemption is enabled at that point in tracing, you really want
> to be using rcu_is_watching().

And yes, at that point in tracing, preemption is still enabled if the
tracepoint was called with preemption enabled.

Thus, we really need to convert that to rcu_is_watching().

-- Steve