When a CPU is offlined all interrupts that have action are migrated to other still online CPUs. However, if the interrupt has chained handler installed this is not done. Chained handlers are used by GPIO drivers which support interrupts, for instance.
When affinity is not corrected properly we end up in situation where some interrupts are not arriving to the online CPUs anymore. For example on Intel Braswell system which has SD-card card detection signal connected to a GPIO the IO-APIC routing entries look like below after CPU1 put offline: pin30, enabled , level, low , V(52), IRR(0), S(0), logical , D(03), M(1) pin31, enabled , level, low , V(42), IRR(0), S(0), logical , D(03), M(1) pin32, enabled , level, low , V(62), IRR(0), S(0), logical , D(03), M(1) pin5b, enabled , level, low , V(72), IRR(0), S(0), logical , D(03), M(1) The problem here is that the destination mask still contains both CPUs even if CPU1 is already offline. This means that the IO-APIC still routes interrupts to the other CPU as well. Fix this by correcting affinity also for interrupts that have chained handler installed. Signed-off-by: Mika Westerberg <mika.westerb...@linux.intel.com> --- Discussion about the issue can be read here: https://lkml.org/lkml/2015/10/1/554 arch/x86/kernel/irq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index f8062aaf5df9..e7cc9f199350 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -440,6 +440,7 @@ void fixup_irqs(void) int break_affinity = 0; int set_affinity = 1; const struct cpumask *affinity; + bool has_user; if (!desc) continue; @@ -451,7 +452,10 @@ void fixup_irqs(void) data = irq_desc_get_irq_data(desc); affinity = irq_data_get_affinity_mask(data); - if (!irq_has_action(irq) || irqd_is_per_cpu(data) || + + has_user = irq_has_action(irq) || irq_has_chained_handler(irq); + + if (!has_user || irqd_is_per_cpu(data) || cpumask_subset(affinity, cpu_online_mask)) { raw_spin_unlock(&desc->lock); continue; -- 2.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/