linux-kernel - Re: [PATCH v2 15/20] rv: Convert the opid monitor to a hybrid automaton

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Message-ID: <db32cd9db7168a28e6d16d16b3bbe905a6c2c9f9.camel@redhat.com>
Date: Mon, 13 Oct 2025 16:14:13 +0200
From: Gabriele Monaco <gmonaco@...hat.com>
To: Nam Cao <namcao@...utronix.de>, linux-kernel@...r.kernel.org, Steven
 Rostedt <rostedt@...dmis.org>, Jonathan Corbet <corbet@....net>, Masami
 Hiramatsu	 <mhiramat@...nel.org>, linux-trace-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org
Cc: Tomas Glozar <tglozar@...hat.com>, Juri Lelli <jlelli@...hat.com>, Clark
 Williams <williams@...hat.com>, John Kacur <jkacur@...hat.com>
Subject: Re: [PATCH v2 15/20] rv: Convert the opid monitor to a hybrid
 automaton

On Fri, 2025-10-10 at 16:29 +0200, Nam Cao wrote:
> > +		 * If CONFIG_PREEMPTION is enabled, then the tracepoint
> > itself disables
> > +		 * preemption (adding one to the preempt_count). Since we
> > are
> > +		 * interested in the preempt_count at the time the
> > tracepoint was
> > +		 * hit, we consider 1 as still enabled.
> > +		 */
> > +		if (IS_ENABLED(CONFIG_PREEMPTION))
> > +			return (preempt_count() & PREEMPT_MASK) > 1;
> 
> FYI, there is plan to keep preemption enabled during tracepoint
> handling. So keep that in mind when this monitor breaks.

Right, I've heard of it, thanks for the heads up. I'll adapt the monitors once
that happens.

Thanks,
Gabriele