From e2c12739ccf76aae12e9e949526a475b9d17adaa Mon Sep 17 00:00:00 2001 From: Vincent Whitchurch Date: Thu, 6 Jul 2023 16:22:25 +0200 Subject: genirq: Prevent nested thread vs synchronize_hardirq() deadlock There is a possibility of deadlock if synchronize_hardirq() is called when the nested threaded interrupt is active. The following scenario was observed on a uniprocessor PREEMPT_NONE system: Thread 1 Thread 2 handle_nested_thread() Set INPROGRESS Call ->thread_fn() thread_fn goes to sleep free_irq() __synchronize_hardirq() Busy-loop forever waiting for INPROGRESS to be cleared The INPROGRESS flag is only supposed to be used for hard interrupt handlers. Remove the incorrect usage in the nested threaded interrupt case and instead re-use the threads_active / wait_for_threads mechanism to wait for nested threaded interrupts to complete. Signed-off-by: Vincent Whitchurch Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230613-genirq-nested-v3-1-ae58221143eb@axis.com --- kernel/irq/chip.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'kernel/irq/chip.c') diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index ee8c0acf39df..dc94e0bf2c94 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -473,11 +473,12 @@ void handle_nested_irq(unsigned int irq) action = desc->action; if (unlikely(!action || irqd_irq_disabled(&desc->irq_data))) { desc->istate |= IRQS_PENDING; - goto out_unlock; + raw_spin_unlock_irq(&desc->lock); + return; } kstat_incr_irqs_this_cpu(desc); - irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS); + atomic_inc(&desc->threads_active); raw_spin_unlock_irq(&desc->lock); action_ret = IRQ_NONE; @@ -487,11 +488,7 @@ void handle_nested_irq(unsigned int irq) if (!irq_settings_no_debug(desc)) note_interrupt(desc, action_ret); - raw_spin_lock_irq(&desc->lock); - irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS); - -out_unlock: - raw_spin_unlock_irq(&desc->lock); + wake_threads_waitq(desc); } EXPORT_SYMBOL_GPL(handle_nested_irq); -- cgit v1.2.3