From: Naman Jain <[email protected]> Sent: Sunday, September 6, 2026 11:51 PM > > 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. When the outermost chip does not implement > irq_retrigger(), the pending interrupt is silently dropped, which can > lead to lost interrupts on CPU hot-unplug. > > Keep calling the outermost chip's irq_retrigger() when it is present, > but fall back to irq_chip_retrigger_hierarchy() otherwise, which walks > up the interrupt hierarchy until it finds a chip that implements > irq_retrigger(). > > While at it, use a scoped guard for desc->lock. VECTOR_RETRIGGERED is > now set only when the retrigger succeeds instead of unconditionally, > which is harmless today since apic_retrigger_irq() always returns 1. > > Suggested-by: Thomas Gleixner <[email protected]> > Reviewed-by: Shradha Gupta <[email protected]> > Signed-off-by: Naman Jain <[email protected]>
Reviewed-by: Michael Kelley <[email protected]> > --- > arch/x86/kernel/irq.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c > index 30122f0b3af96..e0163f7ac7368 100644 > --- a/arch/x86/kernel/irq.c > +++ b/arch/x86/kernel/irq.c > @@ -470,6 +470,7 @@ void fixup_irqs(void) > struct irq_desc *desc; > struct irq_data *data; > struct irq_chip *chip; > + int ret; > > irq_migrate_all_off_this_cpu(); > > @@ -490,21 +491,23 @@ void fixup_irqs(void) > * 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]))) > + 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); > + guard(raw_spinlock)(&desc->lock); > data = irq_desc_get_irq_data(desc); > chip = irq_data_get_irq_chip(data); > - if (chip->irq_retrigger) { > - chip->irq_retrigger(data); > + if (chip->irq_retrigger) > + ret = chip->irq_retrigger(data); > + else > + ret = irq_chip_retrigger_hierarchy(data); > + if (ret) > __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 >
