Messages in this thread | | | Date | Wed, 29 Sep 2021 11:15:09 +0800 | From | Pingfan Liu <> | Subject | Re: [PATCHv2 3/5] kernel/irq: make irq_{enter,exit}() in handle_domain_irq() arch optional |
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On Tue, Sep 28, 2021 at 09:55:00AM +0100, Mark Rutland wrote: > On Fri, Sep 24, 2021 at 09:28:35PM +0800, Pingfan Liu wrote: > > handle_domain_irq() contains two major parts: > > -1. irq_enter()/irq_exit(), which serves as hooks for rcu and trace etc. > > -2. irq mapping and dispatching > > > > After the introduction of irqentry_enter()/irqentry_exit() and arch > > specific counterpart (e.g. arm64), roughly speaking, rcu_irq_enter() has > > already been called. Hence here comes requirement to move > > irq_enter/irq_exit out of handle_domain_irq(). And arches should handle > > about irq_enter_rcu()/irq_exit_rcu() by themself. > > > > Since there is still arches, which does not adopt irqentry_enter(), let > > irq_enter()/irq_exit() arch optional in handle_domain_irq(). > > The patch below looks good to me, but the commit message is a little > hard to follow. How about: > > 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. > Thanks for your precious time to improve the log. It looks great, and I will use it in V2. I will keep learning to improve my level of log.
> With that commit message: > > Reviewed-by: Mark Rutland <mark.rutland@arm.com> > Thanks,
Pingfan
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