From: Marc Zyngier <maz@kernel.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Ard Biesheuvel <ardb@kernel.org>
Subject: Re: [PATCH 2/3] irqchip/gic-v3-its: Postpone LPI pending table freeing and memreserve
Date: Mon, 25 Oct 2021 12:57:45 +0100 [thread overview]
Message-ID: <878ryhb9l2.wl-maz@kernel.org> (raw)
In-Reply-To: <87a6iyju92.mognet@arm.com>
On Sun, 24 Oct 2021 16:51:53 +0100,
Valentin Schneider <valentin.schneider@arm.com> wrote:
>
> What we could do instead is only have a PREALLOCATED flag (or RESERVED; in
> any case just one rather than two) set in its_cpu_init_lpis(), and ensure
> each CPU only ever executes the body of the callback exactly once.
>
> if (already_booted())
> return 0;
>
> if (PREALLOCATED)
> its_free_pending_table();
> else
> gic_reserve_range();
>
> out:
> // callback removal faff here
> return 0;
>
> Unfortunately, the boot CPU will already be present in
> cpus_booted_once_mask when this is first invoked for the BP, so AFAICT we'd
> need some new tracking utility (either a new RDIST_LOCAL flag or a separate
> cpumask).
>
> WDYT?
It'd certainly look saner. You may even be able to take advantage of
the fact that the boot CPU is always 0.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-10-25 11:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-22 10:33 [PATCH 0/3] irqchip/gic-v3-its: Fix LPI pending table handling vs PREEMPT_RT Valentin Schneider
2021-10-22 10:33 ` [PATCH 1/3] irqchip/gic-v3-its: Give the percpu rdist struct its own flags field Valentin Schneider
2021-10-23 9:10 ` Marc Zyngier
2021-10-24 15:50 ` Valentin Schneider
2021-10-22 10:33 ` [PATCH 2/3] irqchip/gic-v3-its: Postpone LPI pending table freeing and memreserve Valentin Schneider
2021-10-23 9:48 ` Marc Zyngier
2021-10-24 15:51 ` Valentin Schneider
2021-10-25 11:57 ` Marc Zyngier [this message]
2021-10-22 10:33 ` [PATCH 3/3] irqchip/gic-v3-its: Limit memreserve cpuhp state lifetime Valentin Schneider
2021-10-23 10:37 ` Marc Zyngier
2021-10-24 15:52 ` Valentin Schneider
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