linux-kernel - Re: [PATCH v2 0/2] bitmap_parselist: support 'all' semantics

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Date:   Wed, 21 Apr 2021 10:30:08 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Yury Norov <yury.norov@...il.com>
Cc:     linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
        linux-doc@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Jonathan Corbet <corbet@....net>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v2 0/2] bitmap_parselist: support 'all' semantics

On Tue, Apr 20, 2021 at 08:13:24PM -0700, Yury Norov wrote:
> RCU code supports a special group 'all' which selects all bits in a bitmap.
> We have recently added 'N' extension for bitmap parse, so that '0-N' would
> have exactly the same meaning as 'all'. But because the 'all' is already
> used by RCU, it would be reasonable to support it in core bitmap code as a
> common and easy-readable alias for '0-N'.
> 
> Moving the 'all' support to core bitmap code adds another level of
> flexibility for system configuration by supporting patterns. For example,
> every second bit in cpumask may be selected like this:
> 	isolcpus=all:1/2
> 
> v2:
>  - cleanup patch 1;
>  - in patch 2 explain why dropping legacy comment.

Nice!

I have pulled this into -rcu with some minor updates, including replacing
the "isolcpus=all" with "rcu_nocbs=all:1/2" per Steve Rostedt's feedback.

Could you please check to make sure that I didn't mess anything up?

If tests go well, this will go into -next later today or tomorrow.
Although I cannot prove that this will not make the upcoming merge window,
but Murphy insists that it will instead be the v5.14 merge window.

							Thanx, Paul

> Yury Norov (2):
>   bitmap_parse: support 'all' semantics
>   rcu/tree_plugin: don't handle the case of 'all' CPU range
> 
>  Documentation/admin-guide/kernel-parameters.rst | 5 +++++
>  kernel/rcu/tree_plugin.h                        | 9 +++------
>  lib/bitmap.c                                    | 9 +++++++++
>  lib/test_bitmap.c                               | 7 +++++++
>  4 files changed, 24 insertions(+), 6 deletions(-)
> 
> -- 
> 2.25.1
>