| Message ID | 20211001144406.7719-1-kernelfans@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | arm64/irqentry: remove duplicate housekeeping of rcu | expand |
On Fri, 01 Oct 2021 15:44:03 +0100, Pingfan Liu <kernelfans@gmail.com> 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. > > 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. > > V3 -> V4: > address Signed-off-by in [2/3] > improve commit log in [3/3] > > 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 > V3: https://lore.kernel.org/linux-arm-kernel/20210930131708.35328-1-kernelfans@gmail.com > > > Cc: "Paul E. McKenney" <paulmck@kernel.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Marc Zyngier <maz@kernel.org> > Cc: Joey Gouly <joey.gouly@arm.com> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Julien Thierry <julien.thierry@arm.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Yuichi Ito <ito-yuichi@fujitsu.com> > Cc: linux-kernel@vger.kernel.org > To: linux-arm-kernel@lists.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: avoid double-accounting IRQ RCU entry > > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/entry-common.c | 47 +++++++++++++++++--------------- > kernel/irq/Kconfig | 3 ++ > kernel/irq/irqdesc.c | 4 +++ > 4 files changed, 33 insertions(+), 22 deletions(-) Given that most of the changes are in the arm64 tree, it'd be good if the whole series went via the arm64 tree, most probably as a fix. Thanks, M.
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
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. V3 -> V4: address Signed-off-by in [2/3] improve commit log in [3/3] 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 V3: https://lore.kernel.org/linux-arm-kernel/20210930131708.35328-1-kernelfans@gmail.com Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Joey Gouly <joey.gouly@arm.com> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Julien Thierry <julien.thierry@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuichi Ito <ito-yuichi@fujitsu.com> Cc: linux-kernel@vger.kernel.org To: linux-arm-kernel@lists.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: avoid double-accounting IRQ RCU entry arch/arm64/Kconfig | 1 + arch/arm64/kernel/entry-common.c | 47 +++++++++++++++++--------------- kernel/irq/Kconfig | 3 ++ kernel/irq/irqdesc.c | 4 +++ 4 files changed, 33 insertions(+), 22 deletions(-)