linux-kernel - Re: [PATCH 12/15] tick: Move individual bit features to debuggable mask accesses

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Date: Thu, 25 Jan 2024 10:41:10 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Frederic Weisbecker <frederic@...nel.org>, LKML
 <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>, Ingo Molnar
 <mingo@...nel.org>, Anna-Maria Behnsen <anna-maria@...utronix.de>, Peng
 Liu <liupeng17@...ovo.com>, Joel Fernandes <joel@...lfernandes.org>
Subject: Re: [PATCH 12/15] tick: Move individual bit features to debuggable
 mask accesses

On Wed, Jan 24 2024 at 18:04, Frederic Weisbecker wrote:
> The individual bitfields of struct tick_sched must be modified from
> IRQs disabled places, otherwise local modifications can race due to them
> sharing the same memory storage.
>
> The recent move of the "got_idle_tick" bitfield to its own storage shows
> that the use of these bitfields, as pretty as they look, can be as much
> error prone.
>
> In order to avoid future issues of the like and make sure that those
> bitfields are safely accessed, move those flags to an explicit mask
> along with a mutator function performing the basic IRQs disabled sanity
> check.
>
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>