To ensure that we handle all the pending interrupts (destined for this cpu that is going down) in the interrupt subsystem before the cpu goes offline, fixup_irqs() does: local_irq_enable(); mdelay(1); local_irq_disable(); Enabling interrupts is not a good thing as this cpu is already offline. So this patch replaces that logic with, mdelay(1); check APIC_IRR bits Retrigger the irq at the new destination if any interrupt has arrived via IPI. For IO-APIC level triggered interrupts, this retrigger IPI will appear as an edge interrupt. ack_apic_level() will detect this condition and IO-APIC RTE's remoteIRR is cleared using directed EOI(using IO-APIC EOI register) on Intel platforms and for others it uses the existing mask+edge logic followed by unmask+level. We can also remove mdelay() and then send spuriuous interrupts to new cpu targets for all the irqs that were handled previously by this cpu that is going offline. While it works, I have seen spurious interrupt messages (nothing wrong but still annoying messages during cpu offline, which can be seen during suspend/resume etc) Signed-off-by: Suresh Siddha Signed-off-by: Gary Hade Cc: Eric W. Biederman --- arch/x86/kernel/irq.c | 32 ++++++++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-) Index: tip/arch/x86/kernel/irq.c =================================================================== --- tip.orig/arch/x86/kernel/irq.c +++ tip/arch/x86/kernel/irq.c @@ -279,7 +279,7 @@ EXPORT_SYMBOL_GPL(vector_used_by_percpu_ /* A cpu has been removed from cpu_online_mask. Reset irq affinities. */ void fixup_irqs(void) { - unsigned int irq; + unsigned int irq, vector; static int warned; struct irq_desc *desc; @@ -334,9 +334,33 @@ void fixup_irqs(void) printk("Cannot set affinity for irq %i\n", irq); } - /* That doesn't seem sufficient. Give it 1ms. */ - local_irq_enable(); + /* + * We can remove mdelay() and then send spuriuous interrupts to + * new cpu targets for all the irqs that were handled previously by + * this cpu. While it works, I have seen spurious interrupt messages + * (nothing wrong but still...). + * + * So for now, retain mdelay(1) and check the IRR and then send those + * interrupts to new targets as this cpu is already offlined... + */ mdelay(1); - local_irq_disable(); + + for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) { + unsigned int irr; + + if (__get_cpu_var(vector_irq)[vector] < 0) + continue; + + irr = apic_read(APIC_IRR + (vector / 32 * 0x10)); + if (irr & (1 << (vector % 32))) { + irq = __get_cpu_var(vector_irq)[vector]; + + desc = irq_to_desc(irq); + spin_lock(&desc->lock); + if (desc->chip->retrigger) + desc->chip->retrigger(irq); + spin_unlock(&desc->lock); + } + } } #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/