Re: [PATCH 2/3] irqchip/irq-sifive-plic: Fixup couldn't broadcast to multi CPUs

From: Anup Patel
Date: Fri Oct 23 2020 - 08:17:11 EST


On Fri, Oct 23, 2020 at 3:48 PM <guoren@xxxxxxxxxx> wrote:
>
> From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
>
> If "echo 3 > /proc/irq/1/smp_affinity", we want irq 1 could be
> broadcast to CPU0 & CPU1 and one of them would pick up the irq
> handler.
>
> But current implementation couldn't let multi CPUs process the
> same IRQ concurrent.
>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> ---
> drivers/irqchip/irq-sifive-plic.c | 23 ++++++-----------------
> 1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 2e56576..0003322 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -114,15 +114,12 @@ static inline void plic_irq_toggle(const struct cpumask *mask,
> static void plic_irq_unmask(struct irq_data *d)
> {
> struct cpumask amask;
> - unsigned int cpu;
> struct plic_priv *priv = irq_get_chip_data(d->irq);
>
> cpumask_and(&amask, &priv->lmask, cpu_online_mask);
> - cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
> - &amask);
> - if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
> - return;
> - plic_irq_toggle(cpumask_of(cpu), d, 1);
> + cpumask_and(&amask, &amask, irq_data_get_affinity_mask(d));
> +
> + plic_irq_toggle(&amask, d, 1);
> }
>
> static void plic_irq_mask(struct irq_data *d)
> @@ -136,24 +133,16 @@ static void plic_irq_mask(struct irq_data *d)
> static int plic_set_affinity(struct irq_data *d,
> const struct cpumask *mask_val, bool force)
> {
> - unsigned int cpu;
> struct cpumask amask;
> struct plic_priv *priv = irq_get_chip_data(d->irq);
>
> cpumask_and(&amask, &priv->lmask, mask_val);
> + cpumask_and(&amask, &amask, cpu_online_mask);
>
> - if (force)
> - cpu = cpumask_first(&amask);
> - else
> - cpu = cpumask_any_and(&amask, cpu_online_mask);
> -
> - if (cpu >= nr_cpu_ids)
> - return -EINVAL;
> + irq_data_update_effective_affinity(d, &amask);
>
> plic_irq_toggle(&priv->lmask, d, 0);
> - plic_irq_toggle(cpumask_of(cpu), d, 1);
> -
> - irq_data_update_effective_affinity(d, cpumask_of(cpu));
> + plic_irq_toggle(&amask, d, 1);
>
> return IRQ_SET_MASK_OK_DONE;
> }
> --
> 2.7.4
>

In the past, a similar patch was proposed by Zong Li (SiFive). We
have good reasons to not allow multiple CPUs handle the same IRQ.

Refer, https://lkml.org/lkml/2020/4/26/201

NACK from my side.

Regards,
Anup