linux-kernel - Re: [PATCH 04/13] tracing: Rename kvfree_rcu() to kvfree_rcu

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Message-ID: <29b54f07-b4ce-4eab-bbc2-281672bca5a5@paulmck-laptop>
Date:   Wed, 15 Mar 2023 20:44:17 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Jens Axboe <axboe@...nel.dk>, Uladzislau Rezki <urezki@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Philipp Reisner <philipp.reisner@...bit.com>,
        Bryan Tan <bryantan@...are.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Bob Pearson <rpearsonhpe@...il.com>,
        Ariel Levkovich <lariel@...dia.com>,
        Theodore Ts'o <tytso@....edu>, Julian Anastasov <ja@....bg>
Subject: Re: [PATCH 04/13] tracing: Rename kvfree_rcu() to
 kvfree_rcu_mightsleep()

On Wed, Mar 15, 2023 at 10:23:23PM -0400, Steven Rostedt wrote:
> On Wed, 15 Mar 2023 17:37:30 -0700
> "Paul E. McKenney" <paulmck@...nel.org> wrote:
> 
> > 
> > That does work, and I am guessing that the size increase is not a big
> > problem for you there.
> 
> Well, I was fine with it as long as it stayed in the headers, where
> ugliness is warmly welcomed. Just ask all the #ifdefs.
> 
> > 
> > > That's a cop out, just removing the one case you care about. Fact is
> > > the naming is awful, and the 1/2 argument thing is making it worse.
> > > If a big change is warranted, why not do it right and ACTUALLY
> > > get it right?  
> > 
> > You both do realize that the kvfree_rcu_mightsleep() definition is
> > already in mainline, right?
> > 
> > Anyway, to sum up, kvfree_rcu_mightsleep()--or whatever the entire
> > community eventually decides to name it--can do any of the following:
> > 
> > 1.	Put the pointer into an already allocated array of pointers.
> > 
> > 2.	Allocate a new array of pointers, have the allocation succeed
> > 	without sleeping, then put the pointer into an already allocated
> > 	array of pointers.
> > 
> > 3.	Allocate a new array of pointers, have the allocation succeed
> > 	after sleeping, then put the pointer into an already allocated
> > 	array of pointers.
> > 
> > 4.	Attempt to allocate a new array of pointers, have the allocation
> > 	fail (presumably after sleeping), then invoke synchronize_rcu()
> > 	directly.
> > 
> > Too much fun!  ;-)
> > 
> 
>   kvfree_rcu_kitchen_sink() ?
> 
>   kvfree_rcu_goldie_locks()?
> 
> I honestly like the name "headless" as that perfectly describes the
> difference between kvfree_rcu(arg1, arg2) and kvfree_rcu(arg1).
> 
> Whereas mightsleep() is confusing to me because it doesn't tell me why
> kvfree_rcu() has two args and kvfree_rcu_mightsleep() has only one.
> Usually, code that has two sleep variants is about limiting the
> functionality of the atomic friendly one.

	kvfree_rcu_alloc_head()?
	kvfree_rcu_dynhead()?
	kvfree_rcu_gearhead()?
	kvfree_rcu_radiohead()?
	kvfree_rcu_getahead()?

I don't know about you guys, but to me, kvfree_rcu_mightsleep() is
sounding better and better by comparison...

							Thanx, Paul