From 591d2fb02ea80472d846c0b8507007806bdd69cc Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 21 Jul 2009 11:09:39 +0200 Subject: [PATCH] genirq: Delegate irq affinity setting to the irq thread irq_set_thread_affinity() calls set_cpus_allowed_ptr() which might sleep, but irq_set_thread_affinity() is called with desc->lock held and can be called from hard interrupt context as well. The code has another bug as it does not hold a ref on the task struct as required by set_cpus_allowed_ptr(). Just set the IRQTF_AFFINITY bit in action->thread_flags. The next time the thread runs it migrates itself. Solves all of the above problems nicely. Add kerneldoc to irq_set_thread_affinity() while at it. Signed-off-by: Thomas Gleixner LKML-Reference: --- include/linux/interrupt.h | 2 ++ kernel/irq/internals.h | 3 +-- kernel/irq/manage.c | 50 ++++++++++++++++++++++++++++++++++----- kernel/irq/migration.c | 2 +- 4 files changed, 48 insertions(+), 9 deletions(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 2721f07e9354..88b056ac5629 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -64,11 +64,13 @@ * IRQTF_RUNTHREAD - signals that the interrupt handler thread should run * IRQTF_DIED - handler thread died * IRQTF_WARNED - warning "IRQ_WAKE_THREAD w/o thread_fn" has been printed + * IRQTF_AFFINITY - irq thread is requested to adjust affinity */ enum { IRQTF_RUNTHREAD, IRQTF_DIED, IRQTF_WARNED, + IRQTF_AFFINITY, }; typedef irqreturn_t (*irq_handler_t)(int, void *); diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index 73468253143b..e70ed5592eb9 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -42,8 +42,7 @@ static inline void unregister_handler_proc(unsigned int irq, extern int irq_select_affinity_usr(unsigned int irq); -extern void -irq_set_thread_affinity(struct irq_desc *desc, const struct cpumask *cpumask); +extern void irq_set_thread_affinity(struct irq_desc *desc); /* * Debugging printout: diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 50da67672901..f0de36f13a44 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -80,14 +80,22 @@ int irq_can_set_affinity(unsigned int irq) return 1; } -void -irq_set_thread_affinity(struct irq_desc *desc, const struct cpumask *cpumask) +/** + * irq_set_thread_affinity - Notify irq threads to adjust affinity + * @desc: irq descriptor which has affitnity changed + * + * We just set IRQTF_AFFINITY and delegate the affinity setting + * to the interrupt thread itself. We can not call + * set_cpus_allowed_ptr() here as we hold desc->lock and this + * code can be called from hard interrupt context. + */ +void irq_set_thread_affinity(struct irq_desc *desc) { struct irqaction *action = desc->action; while (action) { if (action->thread) - set_cpus_allowed_ptr(action->thread, cpumask); + set_bit(IRQTF_AFFINITY, &action->thread_flags); action = action->next; } } @@ -112,7 +120,7 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask) if (desc->status & IRQ_MOVE_PCNTXT) { if (!desc->chip->set_affinity(irq, cpumask)) { cpumask_copy(desc->affinity, cpumask); - irq_set_thread_affinity(desc, cpumask); + irq_set_thread_affinity(desc); } } else { @@ -122,7 +130,7 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask) #else if (!desc->chip->set_affinity(irq, cpumask)) { cpumask_copy(desc->affinity, cpumask); - irq_set_thread_affinity(desc, cpumask); + irq_set_thread_affinity(desc); } #endif desc->status |= IRQ_AFFINITY_SET; @@ -176,7 +184,7 @@ int irq_select_affinity_usr(unsigned int irq) spin_lock_irqsave(&desc->lock, flags); ret = setup_affinity(irq, desc); if (!ret) - irq_set_thread_affinity(desc, desc->affinity); + irq_set_thread_affinity(desc); spin_unlock_irqrestore(&desc->lock, flags); return ret; @@ -443,6 +451,34 @@ static int irq_wait_for_interrupt(struct irqaction *action) return -1; } +/* + * Check whether we need to change the affinity of the interrupt thread. + */ +static void +irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) +{ + cpumask_var_t mask; + + if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags)) + return; + + /* + * In case we are out of memory we set IRQTF_AFFINITY again and + * try again next time + */ + if (!alloc_cpumask_var(&mask, GFP_KERNEL)) { + set_bit(IRQTF_AFFINITY, &action->thread_flags); + return; + } + + spin_lock_irq(&desc->lock); + cpumask_copy(mask, desc->affinity); + spin_unlock_irq(&desc->lock); + + set_cpus_allowed_ptr(current, mask); + free_cpumask_var(mask); +} + /* * Interrupt handler thread */ @@ -458,6 +494,8 @@ static int irq_thread(void *data) while (!irq_wait_for_interrupt(action)) { + irq_thread_check_affinity(desc, action); + atomic_inc(&desc->threads_active); spin_lock_irq(&desc->lock); diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c index cfe767ca1545..fcb6c96f2627 100644 --- a/kernel/irq/migration.c +++ b/kernel/irq/migration.c @@ -45,7 +45,7 @@ void move_masked_irq(int irq) < nr_cpu_ids)) if (!desc->chip->set_affinity(irq, desc->pending_mask)) { cpumask_copy(desc->affinity, desc->pending_mask); - irq_set_thread_affinity(desc, desc->pending_mask); + irq_set_thread_affinity(desc); } cpumask_clear(desc->pending_mask);