On Tue, 09 Aug 2022 08:45:22 +0100,
Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
>
> This patch fix a CPU hotplug issue. The EIOINTC master core (the first
> core of an EIOINTC node) should not be disabled at runtime, since it has
> the responsibility of dispatching I/O interrupts.
>
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> ---
> arch/loongarch/kernel/smp.c | 9 +++++++++
> drivers/irqchip/irq-loongson-eiointc.c | 5 +++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
> index 09743103d9b3..54901716f8de 100644
> --- a/arch/loongarch/kernel/smp.c
> +++ b/arch/loongarch/kernel/smp.c
> @@ -242,9 +242,18 @@ void loongson3_smp_finish(void)
>
> static bool io_master(int cpu)
> {
> + int i, node, master;
> +
> if (cpu == 0)
> return true;
>
> + for (i = 1; i < loongson_sysconf.nr_io_pics; i++) {
> + node = eiointc_get_node(i);
> + master = cpu_number_map(node * CORES_PER_EIO_NODE);
> + if (cpu == master)
> + return true;
> + }
> +
> return false;
> }
>
> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> index 170dbc96c7d3..6c99a2ff95f5 100644
> --- a/drivers/irqchip/irq-loongson-eiointc.c
> +++ b/drivers/irqchip/irq-loongson-eiointc.c
> @@ -56,6 +56,11 @@ static void eiointc_enable(void)
> iocsr_write64(misc, LOONGARCH_IOCSR_MISC_FUNC);
> }
>
> +int eiointc_get_node(int id)
> +{
> + return eiointc_priv[id]->node;
> +}
> +
> static int cpu_to_eio_node(int cpu)
> {
> return cpu_logical_map(cpu) / CORES_PER_EIO_NODE;
I don't understand why it has to be this complex and make any use of
the node number.
As I understand it, CPU-0 in any EIOINTC block is a master. So all you
need to find out is whether the CPU number is a multiple of
CORES_PER_EIO_NODE.
Something like:
return (cpu_logical_map(cpu) % CORES_PER_EIO_NODE) == 0;
which doesn't require exporting anything from anywhere?
M.
--
Without deviation from the norm, progress is not possible.
