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 ++++------- kernel/irq/internals.h | 2 ++ kernel/irq/manage.c | 26 ++++++++++++++------------ 3 files changed, 20 insertions(+), 19 deletions(-) (limited to 'kernel/irq') 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); diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index bdd35bb9c735..831f38308466 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -121,6 +121,8 @@ void irq_resend_init(struct irq_desc *desc); bool irq_wait_for_poll(struct irq_desc *desc); void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action); +void wake_threads_waitq(struct irq_desc *desc); + #ifdef CONFIG_PROC_FS extern void register_irq_proc(unsigned int irq, struct irq_desc *desc); extern void unregister_irq_proc(unsigned int irq, struct irq_desc *desc); diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index d2742af0f0fd..d309ba84e08a 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -108,6 +108,16 @@ bool synchronize_hardirq(unsigned int irq) } EXPORT_SYMBOL(synchronize_hardirq); +static void __synchronize_irq(struct irq_desc *desc) +{ + __synchronize_hardirq(desc, true); + /* + * We made sure that no hardirq handler is running. Now verify that no + * threaded handlers are active. + */ + wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active)); +} + /** * synchronize_irq - wait for pending IRQ handlers (on other CPUs) * @irq: interrupt number to wait for @@ -127,16 +137,8 @@ void synchronize_irq(unsigned int irq) { struct irq_desc *desc = irq_to_desc(irq); - if (desc) { - __synchronize_hardirq(desc, true); - /* - * We made sure that no hardirq handler is - * running. Now verify that no threaded handlers are - * active. - */ - wait_event(desc->wait_for_threads, - !atomic_read(&desc->threads_active)); - } + if (desc) + __synchronize_irq(desc); } EXPORT_SYMBOL(synchronize_irq); @@ -1216,7 +1218,7 @@ static irqreturn_t irq_thread_fn(struct irq_desc *desc, return ret; } -static void wake_threads_waitq(struct irq_desc *desc) +void wake_threads_waitq(struct irq_desc *desc) { if (atomic_dec_and_test(&desc->threads_active)) wake_up(&desc->wait_for_threads); @@ -1944,7 +1946,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id) * supports it also make sure that there is no (not yet serviced) * interrupt in flight at the hardware level. */ - __synchronize_hardirq(desc, true); + __synchronize_irq(desc); #ifdef CONFIG_DEBUG_SHIRQ /* -- cgit v1.2.3 From 51a5acce7162185a9b9d695b314a12fc067562b4 Mon Sep 17 00:00:00 2001 From: YueHaibing Date: Thu, 20 Jul 2023 22:36:25 +0800 Subject: genirq: Remove unused extern declaration commit 3795de236d67 ("genirq: Distangle kernel/irq/handle.c") left behind this. Signed-off-by: YueHaibing Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230720143625.29176-1-yuehaibing@huawei.com --- kernel/irq/internals.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'kernel/irq') diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index 831f38308466..bcc7f21db9ee 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -108,8 +108,6 @@ extern int __irq_get_irqchip_state(struct irq_data *data, enum irqchip_irq_state which, bool *state); -extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr); - irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc); irqreturn_t handle_irq_event_percpu(struct irq_desc *desc); irqreturn_t handle_irq_event(struct irq_desc *desc); -- cgit v1.2.3