From: Pingfan Liu <kernelfans@gmail.com>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Mark Rutland <mark.rutland@arm.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Sami Tolvanen <samitolvanen@google.com>,
Julien Thierry <julien.thierry@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Yuichi Ito <ito-yuichi@fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCHv3 1/3] kernel/irq: make irq_{enter, exit}() in handle_domain_irq() arch optional
Date: Fri, 1 Oct 2021 22:33:22 +0800 [thread overview]
Message-ID: <YVccMqMHLeRSCNAd@piliu.users.ipa.redhat.com> (raw)
In-Reply-To: <87sfxlrtqz.wl-maz@kernel.org>
On Fri, Oct 01, 2021 at 10:15:16AM +0100, Marc Zyngier wrote:
> On Thu, 30 Sep 2021 14:17:06 +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.
> >
> > For architectures which do not select the symbol. there should be no
> > functional change as a result of this patch.
> >
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > Reviewed-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > 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
> > ---
> > kernel/irq/Kconfig | 3 +++
> > kernel/irq/irqdesc.c | 4 ++++
> > 2 files changed, 7 insertions(+)
> >
> > diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
> > index fbc54c2a7f23..defa1db2d664 100644
> > --- a/kernel/irq/Kconfig
> > +++ b/kernel/irq/Kconfig
> > @@ -100,6 +100,9 @@ config IRQ_MSI_IOMMU
> > config HANDLE_DOMAIN_IRQ
> > bool
> >
> > +config HAVE_ARCH_IRQENTRY
> > + bool
> > +
> > config IRQ_TIMINGS
> > bool
> >
> > diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> > index 4e3c29bb603c..fd5dd9d278b5 100644
> > --- a/kernel/irq/irqdesc.c
> > +++ b/kernel/irq/irqdesc.c
> > @@ -693,7 +693,9 @@ int handle_domain_irq(struct irq_domain *domain,
> > struct irq_desc *desc;
> > int ret = 0;
> >
> > +#ifndef CONFIG_HAVE_ARCH_IRQENTRY
> > irq_enter();
> > +#endif
>
> nit: I tend to prefer the 'if (!IS_ENABLED(CONFIG_*))' approach.
>
I check the irqdesc.c, the other macro conditional statements have the style
"#ifdef". So if using 'if (!IS_ENABLED(CONFIG_*))', the file looks a
little disharmony.
> >
> > /* The irqdomain code provides boundary checks */
> > desc = irq_resolve_mapping(domain, hwirq);
> > @@ -702,7 +704,9 @@ int handle_domain_irq(struct irq_domain *domain,
> > else
> > ret = -EINVAL;
> >
> > +#ifndef CONFIG_HAVE_ARCH_IRQENTRY
> > irq_exit();
> > +#endif
> > set_irq_regs(old_regs);
> > return ret;
> > }
>
> Apart from that:
>
> Reviewed-by: Marc Zyngier <maz@kernel.org>
>
I am not sure whether you agree with my opinion about the style of macro
and hesitate to include your Reviewed-by.
Could you kindly give your Reviewed-by to my V4, if it is OK for you?
Thanks
Pingfan
next prev parent reply other threads:[~2021-10-01 14:33 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 13:17 [PATCHv3 0/3] arm64/irqentry: remove duplicate housekeeping of rcu Pingfan Liu
2021-09-30 13:17 ` [PATCHv3 1/3] kernel/irq: make irq_{enter,exit}() in handle_domain_irq() arch optional Pingfan Liu
2021-10-01 9:15 ` Marc Zyngier
2021-10-01 14:33 ` Pingfan Liu [this message]
2021-09-30 13:17 ` [PATCHv3 2/3] arm64: entry: refactor EL1 interrupt entry logic Pingfan Liu
2021-09-30 14:00 ` Mark Rutland
2021-10-01 2:27 ` Pingfan Liu
2021-10-01 9:21 ` Marc Zyngier
2021-10-01 14:12 ` Pingfan Liu
2021-09-30 13:17 ` [PATCHv3 3/3] arm64/entry-common: supplement irq accounting Pingfan Liu
2021-09-30 13:53 ` Mark Rutland
2021-10-01 9:22 ` Marc Zyngier
2021-10-01 14:10 ` Pingfan Liu
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