From 1adb0850a1254333d81e64121c80af100c6d6e06 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 28 Apr 2008 17:01:56 +0200 Subject: [PATCH] genirq: reenable a nobody cared disabled irq when a new driver arrives MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Uwe Kleine-Koenig has some strange hardware where one of the shared interrupts can be asserted during boot before the appropriate driver loads. Requesting the shared irq line from another driver result in a spurious interrupt storm which finally disables the interrupt line. I have seen similar behaviour on resume before (the hardware does not work anymore so I can not verify). Change the spurious disable logic to increment the disable depth and mark the interrupt with an extra flag which allows us to reenable the interrupt when a new driver arrives which requests the same irq line. In the worst case this will disable the irq again via the spurious trap, but there is a decent chance that the new driver is the one which can handle the already asserted interrupt and makes the box usable again. Eric Biederman said further: This case also happens on a regular basis in kdump kernels where we deliberately don't shutdown the hardware before starting the new kernel. This patch should reduce the need for using irqpoll in that situation by a small amount. Signed-off-by: Thomas Gleixner Tested-and-Acked-by: Uwe Kleine-König --- include/linux/irq.h | 1 + kernel/irq/manage.c | 49 ++++++++++++++++++++++++++++++++----------------- kernel/irq/spurious.c | 4 ++-- 3 files changed, 35 insertions(+), 19 deletions(-) diff --git a/include/linux/irq.h b/include/linux/irq.h index 1883a85..552e0ec 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -61,6 +61,7 @@ typedef void (*irq_flow_handler_t)(unsigned int irq, #define IRQ_WAKEUP 0x00100000 /* IRQ triggers system wakeup */ #define IRQ_MOVE_PENDING 0x00200000 /* need to re-target IRQ destination */ #define IRQ_NO_BALANCING 0x00400000 /* IRQ is excluded from balancing */ +#define IRQ_SPURIOUS_DISABLED 0x00800000 /* IRQ was disabled by the spurious trap */ #ifdef CONFIG_IRQ_PER_CPU # define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 46e4ad1..46d6611 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -150,6 +150,26 @@ void disable_irq(unsigned int irq) } EXPORT_SYMBOL(disable_irq); +static void __enable_irq(struct irq_desc *desc, unsigned int irq) +{ + switch (desc->depth) { + case 0: + printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq); + WARN_ON(1); + break; + case 1: { + unsigned int status = desc->status & ~IRQ_DISABLED; + + /* Prevent probing on this irq: */ + desc->status = status | IRQ_NOPROBE; + check_irq_resend(desc, irq); + /* fall-through */ + } + default: + desc->depth--; + } +} + /** * enable_irq - enable handling of an irq * @irq: Interrupt to enable @@ -169,22 +189,7 @@ void enable_irq(unsigned int irq) return; spin_lock_irqsave(&desc->lock, flags); - switch (desc->depth) { - case 0: - printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq); - WARN_ON(1); - break; - case 1: { - unsigned int status = desc->status & ~IRQ_DISABLED; - - /* Prevent probing on this irq: */ - desc->status = status | IRQ_NOPROBE; - check_irq_resend(desc, irq); - /* fall-through */ - } - default: - desc->depth--; - } + __enable_irq(desc, irq); spin_unlock_irqrestore(&desc->lock, flags); } EXPORT_SYMBOL(enable_irq); @@ -365,7 +370,7 @@ int setup_irq(unsigned int irq, struct irqaction *new) compat_irq_chip_set_default_handler(desc); desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | - IRQ_INPROGRESS); + IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED); if (!(desc->status & IRQ_NOAUTOEN)) { desc->depth = 0; @@ -381,6 +386,16 @@ int setup_irq(unsigned int irq, struct irqaction *new) /* Reset broken irq detection when installing new handler */ desc->irq_count = 0; desc->irqs_unhandled = 0; + + /* + * Check whether we disabled the irq via the spurious handler + * before. Reenable it and give it another chance. + */ + if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) { + desc->status &= ~IRQ_SPURIOUS_DISABLED; + __enable_irq(desc, irq); + } + spin_unlock_irqrestore(&desc->lock, flags); new->irq = irq; diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c index 088dabb..c66d3f1 100644 --- a/kernel/irq/spurious.c +++ b/kernel/irq/spurious.c @@ -209,8 +209,8 @@ void note_interrupt(unsigned int irq, struct irq_desc *desc, * Now kill the IRQ */ printk(KERN_EMERG "Disabling IRQ #%d\n", irq); - desc->status |= IRQ_DISABLED; - desc->depth = 1; + desc->status |= IRQ_DISABLED | IRQ_SPURIOUS_DISABLED; + desc->depth++; desc->chip->disable(irq); } desc->irqs_unhandled = 0; -- 2.7.4