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Date:   Tue, 18 Jan 2022 15:29:07 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Jiri Slaby <jirislaby@kernel.org>
Cc:     Walt Drummond <walt@drummond.us>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>, ar@cs.msu.ru,
        linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
        mm <linux-mm@kvack.org>, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 3/3] status: Display an informational message when the
 VSTATUS character is pressed or TIOCSTAT ioctl is called.
Message-ID: <YebOs1OWRAru2v5B@hirez.programming.kicks-ass.net>
References: <20220118044323.765038-1-walt@drummond.us>
 <20220118044323.765038-3-walt@drummond.us>
 <72a719a0-cd7c-9516-93c2-bd258930b71e@kernel.org>
 <YeamX3ELWyc/BtGp@hirez.programming.kicks-ass.net>
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On Tue, Jan 18, 2022 at 12:37:03PM +0100, Peter Zijlstra wrote:
> > > +static inline struct task_struct *compare(struct task_struct *new,
> > > +					  struct task_struct *old)
> > > +{
> > > +	unsigned int ostate, nstate;
> > > +
> > > +	if (old == NULL)
> > > +		return new;
> > > +
> > > +	ostate = task_state_index(old);
> > > +	nstate = task_state_index(new);
> > > +
> > > +	if (ostate == nstate) {
> 
> That's not an ordered set, please don't do that.

*sigh*.. sorry about that, I can't read, for some reason I thought you
did: ostate < nstate...

> > > +		if (old->start_time > new->start_time)
> > > +			return old;
> > > +		return new;
> > > +	}
> > > +
> > > +	if (ostate < nstate)
> > > +		return old;
> > > +
> > > +	return new;
> > > +}