On Tue, Jul 28, 2026 at 01:51:16PM +0000, Naman Jain wrote:
> fixup_irqs() re-injects a pending interrupt on its new target CPU by
> looking at the outermost domain chip and invoking its irq_retrigger()
> callback directly. That only works when the outermost chip happens to
> install an irq_retrigger() callback, which is not guaranteed for every
> irqchip and could lead to lost interrupts on CPU hot-unplug.
>
> Use irq_chip_retrigger_hierarchy() instead, which walks up the interrupt
> hierarchy until it finds a chip that implements irq_retrigger().
>
> While at it, move the loop-local variables into the loop scope and use a
> scoped guard for desc->lock.
>
> No functional change intended for chips which already provide an
> irq_retrigger() callback on the outermost domain.
>
> Suggested-by: Thomas Gleixner <[email protected]>
> Signed-off-by: Naman Jain <[email protected]>
I can pick this up as part of this series but this requires an ack from
Thomas.
Wei
> ---
> arch/x86/kernel/irq.c | 23 +++++++----------------
> 1 file changed, 7 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
> index 30122f0b3af96..ef1bdd3c4659a 100644
> --- a/arch/x86/kernel/irq.c
> +++ b/arch/x86/kernel/irq.c
> @@ -466,11 +466,6 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_posted_msi_notification)
> /* A cpu has been removed from cpu_online_mask. Reset irq affinities. */
> void fixup_irqs(void)
> {
> - unsigned int vector;
> - struct irq_desc *desc;
> - struct irq_data *data;
> - struct irq_chip *chip;
> -
> irq_migrate_all_off_this_cpu();
>
> /*
> @@ -489,22 +484,18 @@ void fixup_irqs(void)
> * vector_lock because the cpu is already marked !online, so
> * nothing else will touch it.
> */
> - for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
> - if (IS_ERR_OR_NULL(__this_cpu_read(vector_irq[vector])))
> + for (unsigned int vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS;
> vector++) {
> + struct irq_desc *desc = __this_cpu_read(vector_irq[vector]);
> +
> + if (IS_ERR_OR_NULL(desc))
> continue;
>
> if (is_vector_pending(vector)) {
> - desc = __this_cpu_read(vector_irq[vector]);
> -
> - raw_spin_lock(&desc->lock);
> - data = irq_desc_get_irq_data(desc);
> - chip = irq_data_get_irq_chip(data);
> - if (chip->irq_retrigger) {
> - chip->irq_retrigger(data);
> + guard(raw_spinlock)(&desc->lock);
> + if (irq_chip_retrigger_hierarchy(&desc->irq_data))
> __this_cpu_write(vector_irq[vector],
> VECTOR_RETRIGGERED);
> - }
> - raw_spin_unlock(&desc->lock);
> }
> +
> if (__this_cpu_read(vector_irq[vector]) != VECTOR_RETRIGGERED)
> __this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
> }
> --
> 2.43.0
>
>
