linux-kernel - Re: [PATCH 2/2] context_tracking, rcu: Rename RCU_DYNTICKS_IDX to CT_DYNTICKS

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Date: Tue, 9 Apr 2024 12:53:03 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: Valentin Schneider <vschneid@...hat.com>, rcu@...r.kernel.org,
	linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
	Neeraj Upadhyay <quic_neeraju@...cinc.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Josh Triplett <josh@...htriplett.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Zqiang <qiang.zhang1211@...il.com>
Subject: Re: [PATCH 2/2] context_tracking, rcu: Rename RCU_DYNTICKS_IDX to
 CT_DYNTICKS_IDX

On Thu, Apr 04, 2024 at 03:38:40PM +0200, Frederic Weisbecker wrote:
> Le Wed, Mar 27, 2024 at 12:29:02PM +0100, Valentin Schneider a écrit :
> > The symbols relating to the CT_STATE part of context_tracking.state are now
> > all prefixed with CT_STATE.
> > 
> > The RCU dynticks counter part of that atomic variable still involves
> > symbols with different prefixes, align them all to be prefixed with
> > CT_DYNTICKS, as CT_DYNTICKS_MASK already is.
> > 
> > Signed-off-by: Valentin Schneider <vschneid@...hat.com>
> 
> It used to be that RCU extended quiescent state and dynticks enter/exit
> were coupled. But this isn't the case anymore. Nowadays RCU stops watching
> some time later after dynticks is entered.

I knew that consolidation of atomic operations was too good to last...

> I wonder if we shouldn't take advantage of that cleanup for a meaning that
> really reflect that RCU stops watching from there.
> 
> Paul what do you think? CT_EQS_IDX ? CT_RCUEQS_IDX? CT_RCUOFF_IDX? ...?

"After what you just did?  You can just RCU off!!!"

Sorry, couldn't resist...

I am having a hard time getting too excited about the name.  I could
suggest CT_RCU_WATCHING_IDX, but that isn't exactly the shortest
possible name.

							Thanx, Paul