linux-kernel - Re: [PATCH 11/12] irqchip/mips-gic: Report that effective affinity is a single target

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Message-ID: <4d46ab22-dc61-b332-4c98-e6a8bb1921a7@arm.com>
Date:   Tue, 15 Aug 2017 17:44:24 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Paul Burton <paul.burton@...tec.com>
Cc:     linux-kernel@...r.kernel.org, Wei Xu <xuwei5@...ilicon.com>,
        James Hogan <james.hogan@...tec.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Gregory Clement <gregory.clement@...e-electrons.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Kevin Cernekee <cernekee@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        Matt Redfearn <matt.redfearn@...tec.com>
Subject: Re: [PATCH 11/12] irqchip/mips-gic: Report that effective affinity is
 a single target

On 15/08/17 17:23, Paul Burton wrote:
> Hi Marc,
> 
> On Tuesday, 15 August 2017 04:34:46 PDT Marc Zyngier wrote:
>> The MIPS GIC driver only targets a single CPU at a time, even if
>> the notional affinity is wider. Let's inform the core code
>> about this.
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
>> ---
>>  drivers/irqchip/Kconfig        | 1 +
>>  drivers/irqchip/irq-mips-gic.c | 2 ++
>>  2 files changed, 3 insertions(+)
>>
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index 39bfa5b25b54..bca9a88012f0 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -141,6 +141,7 @@ config IRQ_MIPS_CPU
>>  	select GENERIC_IRQ_IPI if SYS_SUPPORTS_MULTITHREADING
>>  	select IRQ_DOMAIN
>>  	select IRQ_DOMAIN_HIERARCHY if GENERIC_IRQ_IPI
>> +	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
>>
>>  config CLPS711X_IRQCHIP
>>  	bool
>> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
>> index 6ab1d3afec02..e075cb25fad6 100644
>> --- a/drivers/irqchip/irq-mips-gic.c
>> +++ b/drivers/irqchip/irq-mips-gic.c
>> @@ -463,6 +463,7 @@ static int gic_set_affinity(struct irq_data *d, const
>> struct cpumask *cpumask, set_bit(irq,
>> pcpu_masks[cpumask_first(&tmp)].pcpu_mask);
>>
>>  	cpumask_copy(irq_data_get_affinity_mask(d), cpumask);
>> +	irq_data_update_effective_affinity(d, cpumask);
> 
> This doesn't seem right - it's just setting the effective affinity to the same 
> as affinity, not taking into account CPU restrictions at all. I think this 
> should be:
> 
>   irq_data_update_effective_affinity(d, cpumask_of(cpumask_first(&tmp)));
> 
> (or something cleaner but to that effect)

Gah, you're absolutely right (/me plugs brain back in). How about something like this:

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index e075cb25fad6..6461380ff1a4 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -445,25 +445,27 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *cpumask,
 	unsigned int irq = GIC_HWIRQ_TO_SHARED(d->hwirq);
 	cpumask_t	tmp = CPU_MASK_NONE;
 	unsigned long	flags;
-	int		i;
+	int		i, cpu;
 
 	cpumask_and(&tmp, cpumask, cpu_online_mask);
 	if (cpumask_empty(&tmp))
 		return -EINVAL;
 
+	cpu = cpumask_first(&tmp);
+
 	/* Assumption : cpumask refers to a single CPU */
 	spin_lock_irqsave(&gic_lock, flags);
 
 	/* Re-route this IRQ */
-	gic_map_to_vpe(irq, mips_cm_vp_id(cpumask_first(&tmp)));
+	gic_map_to_vpe(irq, mips_cm_vp_id(cpu));
 
 	/* Update the pcpu_masks */
 	for (i = 0; i < min(gic_vpes, NR_CPUS); i++)
 		clear_bit(irq, pcpu_masks[i].pcpu_mask);
-	set_bit(irq, pcpu_masks[cpumask_first(&tmp)].pcpu_mask);
+	set_bit(irq, pcpu_masks[cpu].pcpu_mask);
 
 	cpumask_copy(irq_data_get_affinity_mask(d), cpumask);
-	irq_data_update_effective_affinity(d, cpumask);
+	irq_data_update_effective_affinity(d, cpumask_of(cpu));
 	spin_unlock_irqrestore(&gic_lock, flags);
 
 	return IRQ_SET_MASK_OK_NOCOPY;

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...