genirq: Robustify handle_percpu_devid_irq()

The percpu_devid handler is not robust against spurious interrupts. If a
spurious interrupt happens and no action is installed then the handler
crashes with a NULL pointer dereference.

Add a sanity check for this and log the wreckage once in dmesg.

Reported-by: Majun <majun258@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: guohanjun@huawei.com
Cc: dingtianhong@huawei.com
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1609021436160.5647@nanos

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b4c1bc7..93c373a 100644 (file)
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -756,7 +756,6 @@ void handle_percpu_devid_irq(struct irq_desc *desc)
 {
        struct irq_chip *chip = irq_desc_get_chip(desc);
        struct irqaction *action = desc->action;
-       void *dev_id = raw_cpu_ptr(action->percpu_dev_id);
        unsigned int irq = irq_desc_get_irq(desc);
        irqreturn_t res;
 
@@ -765,9 +764,20 @@ void handle_percpu_devid_irq(struct irq_desc *desc)
        if (chip->irq_ack)
                chip->irq_ack(&desc->irq_data);
 
-       trace_irq_handler_entry(irq, action);
-       res = action->handler(irq, dev_id);
-       trace_irq_handler_exit(irq, action, res);
+       if (likely(action)) {
+               trace_irq_handler_entry(irq, action);
+               res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id));
+               trace_irq_handler_exit(irq, action, res);
+       } else {
+               unsigned int cpu = smp_processor_id();
+               bool enabled = cpumask_test_cpu(cpu, desc->percpu_enabled);
+
+               if (enabled)
+                       irq_percpu_disable(desc, cpu);
+
+               pr_err_once("Spurious%s percpu IRQ%u on CPU%u\n",
+                           enabled ? " and unmasked" : "", irq, cpu);
+       }
 
        if (chip->irq_eoi)
                chip->irq_eoi(&desc->irq_data);