linux-kernel - Re: [PATCHv4 0/3] arm64/irqentry: remove duplicate housekeeping of rcu

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Date:   Tue,  5 Oct 2021 18:17:25 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     linux-arm-kernel@...ts.infradead.org,
        Pingfan Liu <kernelfans@...il.com>
Cc:     Will Deacon <will@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        Yuichi Ito <ito-yuichi@...itsu.com>,
        Julien Thierry <julien.thierry@....com>,
        Marc Zyngier <maz@...nel.org>, Joey Gouly <joey.gouly@....com>,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: Re: [PATCHv4 0/3] arm64/irqentry: remove duplicate housekeeping of rcu

On Fri, 1 Oct 2021 22:44:03 +0800, Pingfan Liu wrote:
> When an IRQ is taken, some accounting needs to be performed to enter and
> exit IRQ context around the IRQ handler. Historically arch code would
> leave this to the irqchip or core IRQ code, but these days we want this
> to happen in exception entry code, and architectures such as arm64 do
> this.
> 
> Currently handle_domain_irq() performs this entry/exit accounting, and
> if used on an architecture where the entry code also does this, the
> entry/exit accounting will be performed twice per IRQ. This is
> problematic as core RCU code such as rcu_is_cpu_rrupt_from_idle()
> depends on this happening once per IRQ, and will not detect quescent
> periods correctly, leading to stall warnings.
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/3] kernel/irq: make irq_{enter,exit}() in handle_domain_irq() arch optional
      https://git.kernel.org/arm64/c/db795cf55b21
[2/3] arm64: entry: refactor EL1 interrupt entry logic
      https://git.kernel.org/arm64/c/ad0d5cfb9535
[3/3] arm64: entry: avoid double-accounting IRQ RCU entry
      https://git.kernel.org/arm64/c/12074b059fdc

-- 
Catalin