From: Mark Rutland <mark.rutland@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
james.morse@arm.com, marcan@marcan.st, tglx@linutronix.de,
will@kernel.org
Subject: Re: [PATCH 5/8] arm64: irq: add a default handle_irq panic function
Date: Mon, 22 Feb 2021 11:25:44 +0000 [thread overview]
Message-ID: <20210222112544.GB70951@C02TD0UTHF1T.local> (raw)
In-Reply-To: <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org>
On Mon, Feb 22, 2021 at 10:48:11AM +0000, Marc Zyngier wrote:
> On 2021-02-22 09:59, Mark Rutland wrote:
> > On Fri, Feb 19, 2021 at 11:39:01AM +0000, Mark Rutland wrote:
> > > +void (*handle_arch_irq)(struct pt_regs *) __ro_after_init =
> > > default_handle_irq;
> > >
> > > int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
> > > {
> > > - if (handle_arch_irq)
> > > + if (handle_arch_irq != default_handle_irq)
> > > return -EBUSY;
> > >
> > > handle_arch_irq = handle_irq;
> > > @@ -87,7 +92,7 @@ void __init init_IRQ(void)
> > > init_irq_stacks();
> > > init_irq_scs();
> > > irqchip_init();
> > > - if (!handle_arch_irq)
> > > + if (handle_arch_irq == default_handle_irq)
> > > panic("No interrupt controller found.");
>
> It also seems odd to have both default_handle_irq() that panics,
> and init_IRQ that panics as well. Not a big deal, but maybe
> we should just drop this altogether and get the firework on the
> first interrupt.
My gut feeling was that both were useful, and served slightly different
cases:
* The panic in default_handle_irq() helps if we unexpectedly unmask IRQ
too early. This is mostly a nicety over the current behaviour of
branching to NULL in this case.
* The panic in init_IRQ() gives us a consistent point at which we can
note the absence of a root IRQ controller even if all IRQs are
quiescent. This is a bit nicer to debug than seeing a load of driver
probes fail their request_irq() or whatever.
... so I'd err on the side of keeping both, but if you think otherwise
I'm happy to change this.
Thanks,
Mark.
WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: catalin.marinas@arm.com, marcan@marcan.st,
linux-kernel@vger.kernel.org, james.morse@arm.com,
tglx@linutronix.de, will@kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 5/8] arm64: irq: add a default handle_irq panic function
Date: Mon, 22 Feb 2021 11:25:44 +0000 [thread overview]
Message-ID: <20210222112544.GB70951@C02TD0UTHF1T.local> (raw)
In-Reply-To: <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org>
On Mon, Feb 22, 2021 at 10:48:11AM +0000, Marc Zyngier wrote:
> On 2021-02-22 09:59, Mark Rutland wrote:
> > On Fri, Feb 19, 2021 at 11:39:01AM +0000, Mark Rutland wrote:
> > > +void (*handle_arch_irq)(struct pt_regs *) __ro_after_init =
> > > default_handle_irq;
> > >
> > > int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
> > > {
> > > - if (handle_arch_irq)
> > > + if (handle_arch_irq != default_handle_irq)
> > > return -EBUSY;
> > >
> > > handle_arch_irq = handle_irq;
> > > @@ -87,7 +92,7 @@ void __init init_IRQ(void)
> > > init_irq_stacks();
> > > init_irq_scs();
> > > irqchip_init();
> > > - if (!handle_arch_irq)
> > > + if (handle_arch_irq == default_handle_irq)
> > > panic("No interrupt controller found.");
>
> It also seems odd to have both default_handle_irq() that panics,
> and init_IRQ that panics as well. Not a big deal, but maybe
> we should just drop this altogether and get the firework on the
> first interrupt.
My gut feeling was that both were useful, and served slightly different
cases:
* The panic in default_handle_irq() helps if we unexpectedly unmask IRQ
too early. This is mostly a nicety over the current behaviour of
branching to NULL in this case.
* The panic in init_IRQ() gives us a consistent point at which we can
note the absence of a root IRQ controller even if all IRQs are
quiescent. This is a bit nicer to debug than seeing a load of driver
probes fail their request_irq() or whatever.
... so I'd err on the side of keeping both, but if you think otherwise
I'm happy to change this.
Thanks,
Mark.
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next prev parent reply other threads:[~2021-02-22 11:28 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 11:38 [PATCH 0/8] arm64: Support FIQ controller registration Mark Rutland
2021-02-19 11:38 ` Mark Rutland
2021-02-19 11:38 ` [PATCH 1/8] ARM: ep93xx: Select GENERIC_IRQ_MULTI_HANDLER directly Mark Rutland
2021-02-19 11:38 ` Mark Rutland
2021-02-19 11:38 ` [PATCH 2/8] irqchip: Do not blindly select CONFIG_GENERIC_IRQ_MULTI_HANDLER Mark Rutland
2021-02-19 11:38 ` Mark Rutland
2021-02-19 11:38 ` [PATCH 3/8] genirq: Allow architectures to override set_handle_irq() fallback Mark Rutland
2021-02-19 11:38 ` Mark Rutland
2021-02-19 11:39 ` [PATCH 4/8] arm64: don't use GENERIC_IRQ_MULTI_HANDLER Mark Rutland
2021-02-19 11:39 ` Mark Rutland
2021-02-19 11:39 ` [PATCH 5/8] arm64: irq: add a default handle_irq panic function Mark Rutland
2021-02-19 11:39 ` Mark Rutland
2021-02-22 9:59 ` Mark Rutland
2021-02-22 9:59 ` Mark Rutland
2021-02-22 10:48 ` Marc Zyngier
2021-02-22 10:48 ` Marc Zyngier
2021-02-22 11:25 ` Mark Rutland [this message]
2021-02-22 11:25 ` Mark Rutland
2021-02-22 11:43 ` Marc Zyngier
2021-02-22 11:43 ` Marc Zyngier
2021-02-22 12:06 ` Mark Rutland
2021-02-22 12:06 ` Mark Rutland
2021-02-22 12:23 ` Marc Zyngier
2021-02-22 12:23 ` Marc Zyngier
2021-02-19 11:39 ` [PATCH 6/8] arm64: entry: factor irq triage logic into macros Mark Rutland
2021-02-19 11:39 ` Mark Rutland
2021-02-19 11:39 ` [PATCH 7/8] arm64: Always keep DAIF.[IF] in sync Mark Rutland
2021-02-19 11:39 ` Mark Rutland
2021-02-19 17:25 ` [PATCH 7/8 v1.5] " Hector Martin
2021-02-19 17:25 ` Hector Martin
2021-02-19 18:26 ` Mark Rutland
2021-02-19 18:26 ` Mark Rutland
2021-02-22 17:39 ` Hector Martin
2021-02-22 17:39 ` Hector Martin
2021-02-22 18:43 ` Mark Rutland
2021-02-22 18:43 ` Mark Rutland
2021-02-19 11:39 ` [PATCH 8/8] arm64: irq: allow FIQs to be handled Mark Rutland
2021-02-19 11:39 ` Mark Rutland
2021-02-19 15:37 ` Joey Gouly
2021-02-19 15:37 ` Joey Gouly
2021-02-19 18:18 ` Mark Rutland
2021-02-19 18:18 ` Mark Rutland
2021-02-19 15:41 ` [PATCH 0/8] arm64: Support FIQ controller registration Hector Martin
2021-02-19 15:41 ` Hector Martin
2021-02-19 16:13 ` Mark Rutland
2021-02-19 16:13 ` Mark Rutland
2021-02-19 18:10 ` Marc Zyngier
2021-02-19 18:10 ` Marc Zyngier
2021-02-24 14:06 ` Mark Rutland
2021-02-24 14:06 ` Mark Rutland
2021-02-24 14:32 ` Marc Zyngier
2021-02-24 14:32 ` Marc Zyngier
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