From 72218d74c9c57b8ea36c2a58875dff406fc10462 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Thu, 12 Jun 2025 11:32:52 -0700 Subject: [PATCH] genirq/cpuhotplug: Restore affinity even for suspended IRQ Commit 788019eb559f ("genirq: Retain disable depth for managed interrupts across CPU hotplug") tried to make managed shutdown/startup properly reference counted, but it missed the fact that the unplug and hotplug code has an intentional imbalance by skipping IRQS_SUSPENDED interrupts on the "restore" path. This means that if a managed-affinity interrupt was both suspended and managed-shutdown (such as may happen during system suspend / S3), resume skips calling irq_startup_managed(), and would again have an unbalanced depth this time, with a positive value (i.e., remaining unexpectedly masked). This IRQS_SUSPENDED check was introduced in commit a60dd06af674 ("genirq/cpuhotplug: Skip suspended interrupts when restoring affinity") for essentially the same reason as commit 788019eb559f, to prevent that irq_startup() would unconditionally re-enable an interrupt too early. Because irq_startup_managed() now respsects the disable-depth count, the IRQS_SUSPENDED check is not longer needed, and instead, it causes harm. Thus, drop the IRQS_SUSPENDED check, and restore balance. This effectively reverts commit a60dd06af674 ("genirq/cpuhotplug: Skip suspended interrupts when restoring affinity"), because it is replaced by commit 788019eb559f ("genirq: Retain disable depth for managed interrupts across CPU hotplug"). Fixes: 788019eb559f ("genirq: Retain disable depth for managed interrupts across CPU hotplug") Reported-by: Aleksandrs Vinarskis Signed-off-by: Brian Norris Signed-off-by: Thomas Gleixner Tested-by: Aleksandrs Vinarskis Link: https://lore.kernel.org/all/20250612183303.3433234-3-briannorris@chromium.org Closes: https://lore.kernel.org/lkml/24ec4adc-7c80-49e9-93ee-19908a97ab84@gmail.com/ --- kernel/irq/cpuhotplug.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c index f07529ae4895..755346ea9819 100644 --- a/kernel/irq/cpuhotplug.c +++ b/kernel/irq/cpuhotplug.c @@ -210,13 +210,6 @@ static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu) !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity)) return; - /* - * Don't restore suspended interrupts here when a system comes back - * from S3. They are reenabled via resume_device_irqs(). - */ - if (desc->istate & IRQS_SUSPENDED) - return; - if (irqd_is_managed_and_shutdown(data)) irq_startup_managed(desc); -- 2.50.1