linux-kernel - Re: [PATCH 0/2] rcu: Transform kfree_rcu() into kvfree

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Message-ID: <20180207113416.33b6247b@gandalf.local.home>
Date:   Wed, 7 Feb 2018 11:34:16 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>, josh@...htriplett.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        mingo@...hat.com, cl@...ux.com, penberg@...nel.org,
        rientjes@...gle.com, iamjoonsoo.kim@....com,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, brouer@...hat.com, rao.shoaib@...cle.com
Subject: Re: [PATCH 0/2] rcu: Transform kfree_rcu() into kvfree_rcu()

On Wed, 7 Feb 2018 08:18:46 -0800
Matthew Wilcox <willy@...radead.org> wrote:

> Do we need to be able to free any of those objects in order to rename
> kfree_rcu() to just free_rcu()?

I'm just nervous about tightly coupling free_rcu() with all the *free()
from the memory management system. I've been burnt in the past by doing
such things.

What's the down side of having a way of matching *free_rcu() with all
the *free()s? I think it's easier to understand, and rcu doesn't need
to worry about changes of *free() code.

To me:

	kfree_rcu(x);

is just a quick way of doing 'kfree(x)' after a synchronize_rcu() call.

But a "free_rcu(x)", is something I have to think about, because I
don't know from the name exactly what it is doing.

I know this may sound a bit bike shedding, but the less I need to think
about how other sub systems work, the easier it is to concentrate on my
own sub system.

-- Steve