Re: [PATCH v12 7/7] arm64: smp: Mark IPI globals as __ro_after_init

From: Mark Rutland <mark.rutland@arm.com>
To: Douglas Anderson <dianders@chromium.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Sumit Garg <sumit.garg@linaro.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Marc Zyngier <maz@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Masayoshi Mizuma <msys.mizuma@gmail.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Chen-Yu Tsai <wens@csie.org>,
	Lecopzer Chen <lecopzer.chen@mediatek.com>,
	Tomohiro Misono <misono.tomohiro@fujitsu.com>,
	Stephane Eranian <eranian@google.com>,
	kgdb-bugreport@lists.sourceforge.net,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Stephen Boyd <swboyd@chromium.org>,
	ito-yuichi@fujitsu.com, linux-perf-users@vger.kernel.org,
	Ard Biesheuvel <ardb@kernel.org>,
	D Scott Phillips <scott@os.amperecomputing.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Valentin Schneider <vschneid@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v12 7/7] arm64: smp: Mark IPI globals as __ro_after_init
Date: Thu, 31 Aug 2023 11:15:15 +0100	[thread overview]
Message-ID: <ZPBoMx8fsFRnC8gI@FVFF77S0Q05N> (raw)
In-Reply-To: <20230830121115.v12.7.I625d393afd71e1766ef73d3bfaac0b347a4afd19@changeid>

On Wed, Aug 30, 2023 at 12:11:28PM -0700, Douglas Anderson wrote:
> Mark the three IPI-related globals in smp.c as "__ro_after_init" since
> they are only ever set in set_smp_ipi_range(), which is marked
> "__init". This is a better and more secure marking than the old
> "__read_mostly".
> 
> Suggested-by: Stephen Boyd <swboyd@chromium.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> This patch is almost completely unrelated to the rest of the series
> other than the fact that it would cause a merge conflict with the
> series if sent separately. I tacked it on to this series in response
> to Stephen's feedback on v11 of this series [1]. If someone hates it
> (not sure why they would), it could be dropped. If someone loves it,
> it could be promoted to the start of the series and/or land on its own
> (resolving merge conflicts).
> 
> [1] https://lore.kernel.org/r/CAE-0n52iVDgZa8XT8KTMj12c_ESSJt7f7A0fuZ_oAMMqpGcSzA@mail.gmail.com

This looks reasonable to me, so:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> 
> Changes in v12:
> - ("arm64: smp: Mark IPI globals as __ro_after_init") new for v12.
> 
>  arch/arm64/kernel/smp.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 1a53e57c81d0..814d9aa93b21 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -84,9 +84,9 @@ enum ipi_msg_type {
>  	MAX_IPI
>  };
>  
> -static int ipi_irq_base __read_mostly;
> -static int nr_ipi __read_mostly = NR_IPI;
> -static struct irq_desc *ipi_desc[MAX_IPI] __read_mostly;
> +static int ipi_irq_base __ro_after_init;
> +static int nr_ipi __ro_after_init = NR_IPI;
> +static struct irq_desc *ipi_desc[MAX_IPI] __ro_after_init;
>  
>  static void ipi_setup(int cpu);
>  
> -- 
> 2.42.0.283.g2d96d420d3-goog
> 