linux-kernel - [PATCHv3 0/3] arm64/irqentry: remove duplicate housekeeping of rcu

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Date:   Thu, 30 Sep 2021 21:17:05 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Pingfan Liu <kernelfans@...il.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>, Joey Gouly <joey.gouly@....com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Julien Thierry <julien.thierry@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yuichi Ito <ito-yuichi@...itsu.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCHv3 0/3] arm64/irqentry: remove duplicate housekeeping of rcu

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.

As irqchip drivers which use handle_domain_irq() need to work on
architectures with or without their own entry/exit accounting, this
patch makes handle_domain_irq() conditionally perform the entry
accounting depending on a new HAVE_ARCH_IRQENTRY Kconfig symbol that
architectures can select if they perform this entry accounting
themselves.

V2 -> V3:
  Drop other patches and concentrate on the purpose of [3-4/5] of V2.
  And lift the level, where to add {irq_enter,exit}_rcu(), from the
  interrupt controler to exception entry  

History:
V1: https://lore.kernel.org/linux-arm-kernel/1607912752-12481-1-git-send-email-kernelfans@gmail.com
V2: https://lore.kernel.org/linux-arm-kernel/20210924132837.45994-1-kernelfans@gmail.com

Cc: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Marc Zyngier <maz@...nel.org>
Cc: Joey Gouly <joey.gouly@....com>
Cc: Sami Tolvanen <samitolvanen@...gle.com>
Cc: Julien Thierry <julien.thierry@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Yuichi Ito <ito-yuichi@...itsu.com>
Cc: linux-kernel@...r.kernel.org
To: linux-arm-kernel@...ts.infradead.org

Mark Rutland (1):
  arm64: entry: refactor EL1 interrupt entry logic

Pingfan Liu (2):
  kernel/irq: make irq_{enter,exit}() in handle_domain_irq() arch
    optional
  arm64/entry-common: supplement irq accounting

 arch/arm64/Kconfig               |  1 +
 arch/arm64/kernel/entry-common.c | 48 +++++++++++++++++---------------
 kernel/irq/Kconfig               |  3 ++
 kernel/irq/irqdesc.c             |  4 +++
 4 files changed, 34 insertions(+), 22 deletions(-)

-- 
2.31.1