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Date:   Thu, 10 Nov 2022 19:37:12 -0800
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        "rcu@vger.kernel.org" <rcu@vger.kernel.org>,
        "kernel-dev@igalia.com" <kernel-dev@igalia.com>,
        "Guilherme G. Piccoli" <kernel@gpiccoli.net>
Subject: Re: RCU stall on 6.1-rc4 (and some previous releases) related to
 ftrace
Message-ID: <20221111033712.GO725751@paulmck-ThinkPad-P17-Gen-1>
Reply-To: paulmck@kernel.org
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 <20221110191651.3a177417@rorschach.local.home>
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On Thu, Nov 10, 2022 at 07:16:51PM -0500, Steven Rostedt wrote:
> On Thu, 10 Nov 2022 18:25:41 -0300
> "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote:
> 
> > @@ -4184,6 +4184,7 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
> >  		if (rec->flags & FTRACE_FL_DISABLED)
> >  			continue;
> >  
> > +		cond_resched();
> >  		if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
> >  			ret = enter_record(hash, rec, clear_filter);
> >  			if (ret < 0) {
> 
> This isn't where I would put it. I would add it after the if statement.
> That is, at the end of the loop.

I am good either way.  Though one could argue for putting it at the
beginning of the loop in case every element takes that "continue" above...

							Thanx, Paul