linux-kernel - Re: [PATCH 13/13] rcu/kvfree: Eliminate k[v]free

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Message-Id: <D8B84631-860B-41CF-8311-88E220C7254F@joelfernandes.org>
Date:   Sun, 5 Mar 2023 07:56:33 -0500
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Uladzislau Rezki <urezki@...il.com>
Cc:     "Paul E . McKenney" <paulmck@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Jens Axboe <axboe@...nel.dk>,
        Philipp Reisner <philipp.reisner@...bit.com>,
        Bryan Tan <bryantan@...are.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        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 13/13] rcu/kvfree: Eliminate k[v]free_rcu() single argument macro



> On Mar 5, 2023, at 6:41 AM, Uladzislau Rezki <urezki@...il.com> wrote:
> 
> 
>> 
>>>> On Mar 5, 2023, at 5:29 AM, Joel Fernandes <joel@...lfernandes.org> wrote:
>>> 
>>> Hi, All,
>>> 
>>>> On Wed, Feb 1, 2023 at 10:11 AM Uladzislau Rezki (Sony)
>>>> <urezki@...il.com> wrote:
>>>> 
>>>> For a single argument invocations a new kfree_rcu_mightsleep()
>>>> and kvfree_rcu_mightsleep() macroses are used. This is done in
>>>> order to prevent users from calling a single argument from
>>>> atomic contexts as "_mightsleep" prefix signals that it can
>>>> schedule().
>>>> 
>>> 
>>> Since this commit in -dev branch [1] suggests more users still need
>>> conversion, let us drop this single patch for 6.4 and move the rest of
>>> the series forward? Let me know if you disagree.
>>> https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=dev&id=9bf5e3a2626ed474d080f695007541b6ecd6e60b
>>> 
>>> All -- please supply Ack/Review tags for patches 1-12.
>> 
>> Or put another way, what is the transition plan for these remaining users?
>> 
>> I am getting on a plane right now but I can research which users are remaining later.
>> 
> I am not sure. I think we can cover it on the meeting.

Cool, thanks.

> My feeling is
> that, we introduced "_mightsleep" macros first and after that try to
> convert users.

One stopgap could be to add a checkpatch error if anyone tries to use old API,
and then in the meanwhile convert all users.
Though, that requires people listening to checkpatch complaints.

Thanks,

 - Joel


> 
> @Paul what is your view?
> 
> Thanks!
> 
> --
> Uladzislau Rezki