From 591d2fb02ea80472d846c0b8507007806bdd69cc Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 21 Jul 2009 11:09:39 +0200 Subject: 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: --- kernel/irq/internals.h | 3 +-- kernel/irq/manage.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------ kernel/irq/migration.c | 2 +- 3 files changed, 46 insertions(+), 9 deletions(-) (limited to 'kernel/irq') 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); -- cgit v1.2.2 From 61f3826133dc07142935fb5712fc738e19eb5575 Mon Sep 17 00:00:00 2001 From: Bruno Premont Date: Wed, 22 Jul 2009 22:22:32 +0200 Subject: genirq: Fix UP compile failure caused by irq_thread_check_affinity Since genirq: Delegate irq affinity setting to the irq thread (591d2fb02ea80472d846c0b8507007806bdd69cc) compilation with CONFIG_SMP=n fails with following error: /usr/src/linux-2.6/kernel/irq/manage.c: In function 'irq_thread_check_affinity': /usr/src/linux-2.6/kernel/irq/manage.c:475: error: 'struct irq_desc' has no member named 'affinity' make[4]: *** [kernel/irq/manage.o] Error 1 That commit adds a new function irq_thread_check_affinity() which uses struct irq_desc.affinity which is only available for CONFIG_SMP=y. Move that function under #ifdef CONFIG_SMP. [ tglx@brownpaperbag: compile and boot tested on UP and SMP ] Signed-off-by: Bruno Premont LKML-Reference: <20090722222232.2eb3e1c4@neptune.home> Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/irq') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index f0de36f13a44..61c679db4687 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -451,6 +451,7 @@ static int irq_wait_for_interrupt(struct irqaction *action) return -1; } +#ifdef CONFIG_SMP /* * Check whether we need to change the affinity of the interrupt thread. */ @@ -478,6 +479,10 @@ irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) set_cpus_allowed_ptr(current, mask); free_cpumask_var(mask); } +#else +static inline void +irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { } +#endif /* * Interrupt handler thread -- cgit v1.2.2 From ad7d6c7a0654a4bbda3e109f56af713267e96274 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Tue, 4 Aug 2009 09:01:33 -0700 Subject: x86/irq: Fix move_irq_desc() for nodes without ram Don't move it if target node is -1. Signed-off-by: Yinghai Lu LKML-Reference: <4A785B5D.4070702@kernel.org> Signed-off-by: Ingo Molnar --- kernel/irq/numa_migrate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/irq') diff --git a/kernel/irq/numa_migrate.c b/kernel/irq/numa_migrate.c index 2f69bee57bf2..3fd30197da2e 100644 --- a/kernel/irq/numa_migrate.c +++ b/kernel/irq/numa_migrate.c @@ -107,8 +107,8 @@ out_unlock: struct irq_desc *move_irq_desc(struct irq_desc *desc, int node) { - /* those all static, do move them */ - if (desc->irq < NR_IRQS_LEGACY) + /* those static or target node is -1, do not move them */ + if (desc->irq < NR_IRQS_LEGACY || node == -1) return desc; if (desc->node != node) -- cgit v1.2.2 From 2d860ad76f4ee4d2eba0fe3797c8d7cdce432cc0 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 13 Aug 2009 13:05:10 -0700 Subject: genirq: prevent wakeup of freed irq thread free_irq() can remove an irqaction while the corresponding interrupt is in progress, but free_irq() sets action->thread to NULL unconditionally, which might lead to a NULL pointer dereference in handle_IRQ_event() when the hard interrupt context tries to wake up the handler thread. Prevent this by moving the thread stop after synchronize_irq(). No need to set action->thread to NULL either as action is going to be freed anyway. This fixes a boot crash reported against preempt-rt which uses the mainline irq threads code to implement full irq threading. [ tglx: removed local irqthread variable ] Signed-off-by: Linus Torvalds Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) (limited to 'kernel/irq') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 61c679db4687..d222515a5a06 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -761,7 +761,6 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) { struct irq_desc *desc = irq_to_desc(irq); struct irqaction *action, **action_ptr; - struct task_struct *irqthread; unsigned long flags; WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq); @@ -809,9 +808,6 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) desc->chip->disable(irq); } - irqthread = action->thread; - action->thread = NULL; - spin_unlock_irqrestore(&desc->lock, flags); unregister_handler_proc(irq, action); @@ -819,12 +815,6 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) /* Make sure it's not being used on another CPU: */ synchronize_irq(irq); - if (irqthread) { - if (!test_bit(IRQTF_DIED, &action->thread_flags)) - kthread_stop(irqthread); - put_task_struct(irqthread); - } - #ifdef CONFIG_DEBUG_SHIRQ /* * It's a shared IRQ -- the driver ought to be prepared for an IRQ @@ -840,6 +830,13 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) local_irq_restore(flags); } #endif + + if (action->thread) { + if (!test_bit(IRQTF_DIED, &action->thread_flags)) + kthread_stop(action->thread); + put_task_struct(action->thread); + } + return action; } -- cgit v1.2.2 From 69ab849439b506cd8dd2879527fdb64d95dd5211 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 17 Aug 2009 14:07:16 +0200 Subject: genirq: Wake up irq thread after action has been installed The wake_up_process() of the new irq thread in __setup_irq() is too early as the irqaction is not yet fully initialized especially action->irq is not yet set. The interrupt thread might dereference the wrong irq descriptor. Move the wakeup after the action is installed and action->irq has been set. Reported-by: Michael Buesch Signed-off-by: Thomas Gleixner Tested-by: Michael Buesch --- kernel/irq/manage.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel/irq') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index d222515a5a06..0ec9ed831737 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -607,7 +607,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) */ get_task_struct(t); new->thread = t; - wake_up_process(t); } /* @@ -690,6 +689,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) (int)(new->flags & IRQF_TRIGGER_MASK)); } + new->irq = irq; *old_ptr = new; /* Reset broken irq detection when installing new handler */ @@ -707,7 +707,13 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) spin_unlock_irqrestore(&desc->lock, flags); - new->irq = irq; + /* + * Strictly no need to wake it up, but hung_task complains + * when no hard interrupt wakes the thread up. + */ + if (new->thread) + wake_up_process(new->thread); + register_irq_proc(irq, desc); new->dir = NULL; register_handler_proc(irq, new); -- cgit v1.2.2