From f3637a5f2e2eb391ff5757bc83fb5de8f9726464 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 7 Jul 2011 22:32:17 +0200 Subject: irq: Always set IRQF_ONESHOT if no primary handler is specified If no primary handler is specified then a default one is assigned which always returns IRQ_WAKE_THREAD. This handler requires the IRQF_ONESHOT flag on LEVEL / EIO typed irqs because the source of interrupt is not disabled. Since it is required for those users and there is no difference for others it makes sense to add this flag unconditionally. Signed-off-by: Sebastian Andrzej Siewior Link: http://lkml.kernel.org/r/1310070737-18514-1-git-send-email-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/irq/manage.c') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 0a7840aeb0fb..3f9cd4799da7 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1322,6 +1322,7 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler, if (!thread_fn) return -EINVAL; handler = irq_default_primary_handler; + irqflags |= IRQF_ONESHOT; } action = kzalloc(sizeof(struct irqaction), GFP_KERNEL); -- cgit v1.2.3 From b6873807a7143b7d6d8b06809295e559d07d7deb Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Mon, 11 Jul 2011 12:17:31 +0200 Subject: irq: Track the owner of irq descriptor Interrupt descriptors can be allocated from modules. The interrupts are used by other modules, but we have no refcount on the module which provides the interrupts and there is no way to establish one on the device level as the interrupt using module is agnostic to the fact that the interrupt is provided by a module rather than by some builtin interrupt controller. To prevent removal of the interrupt providing module, we can track the owner of the interrupt descriptor, which also provides the relevant irq chip functions in the irq descriptor. request/setup_irq() can now acquire a refcount on the owner module to prevent unloading. free_irq() drops the refcount. Signed-off-by: Sebastian Andrzej Siewior Link: http://lkml.kernel.org/r/20110711101731.GA13804@Chamillionaire.breakpoint.cc Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'kernel/irq/manage.c') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 3f9cd4799da7..2e9425889fa8 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -883,6 +883,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) if (desc->irq_data.chip == &no_irq_chip) return -ENOSYS; + if (!try_module_get(desc->owner)) + return -ENODEV; /* * Some drivers like serial.c use request_irq() heavily, * so we have to be careful not to interfere with a @@ -906,8 +908,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) */ nested = irq_settings_is_nested_thread(desc); if (nested) { - if (!new->thread_fn) - return -EINVAL; + if (!new->thread_fn) { + ret = -EINVAL; + goto out_mput; + } /* * Replace the primary handler which was provided from * the driver for non nested interrupt handling by the @@ -929,8 +933,10 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) t = kthread_create(irq_thread, new, "irq/%d-%s", irq, new->name); - if (IS_ERR(t)) - return PTR_ERR(t); + if (IS_ERR(t)) { + ret = PTR_ERR(t); + goto out_mput; + } /* * We keep the reference to the task struct even if * the thread dies to avoid that the interrupt code @@ -1095,6 +1101,8 @@ out_thread: kthread_stop(t); put_task_struct(t); } +out_mput: + module_put(desc->owner); return ret; } @@ -1203,6 +1211,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) put_task_struct(action->thread); } + module_put(desc->owner); return action; } -- cgit v1.2.3 From 69dd3d8e29e294caaf63eb5e8a72d250279f9e5f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 23 Aug 2011 10:36:51 -0700 Subject: Revert "irq: Always set IRQF_ONESHOT if no primary handler is specified" This reverts commit f3637a5f2e2eb391ff5757bc83fb5de8f9726464. It turns out that this breaks several drivers, one example being OMAP boards which use the on-board OMAP UARTs and the omap-serial driver that will not boot to userspace after the commit. Paul Walmsley reports that enabling CONFIG_DEBUG_SHIRQ reveals 'IRQ handler type mismatch' errors: IRQ handler type mismatch for IRQ 74 current handler: serial idle ... and the reason is that setting IRQF_ONESHOT will now result in those interrupt handlers having different IRQF flags, and thus being unsharable. So the commit log in the reverted commit: "Since it is required for those users and there is no difference for others it makes sense to add this flag unconditionally." is simply not true: there may not be any difference from a "actions at irq time", but there is a *big* difference wrt this flag testing irq management (see __setup_irq() in kernel/irq/manage.c). One solution may be to stop verifying IRQF_ONESHOT in __setup_irq(), but right now the safe course of action is to revert the change. Let's revisit this in a later merge window. Reported-by: Paul Walmsley Cc: Sebastian Andrzej Siewior Requested-by: Alan Cox Acked-by: Thomas Gleixner Signed-off-by: Linus Torvalds --- kernel/irq/manage.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/irq/manage.c') diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 2e9425889fa8..9b956fa20308 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1331,7 +1331,6 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler, if (!thread_fn) return -EINVAL; handler = irq_default_primary_handler; - irqflags |= IRQF_ONESHOT; } action = kzalloc(sizeof(struct irqaction), GFP_KERNEL); -- cgit v1.2.3