[PATCH] Debug shared irqs
Drivers registering IRQ handlers with SA_SHIRQ really ought to be able to
handle an interrupt happening before request_irq() returns. They also
ought to be able to handle an interrupt happening during the start of their
call to free_irq(). Let's test that hypothesis....
[bunk@stusta.de: Kconfig fixes]
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8b961ad..400b12a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -357,6 +357,7 @@
struct irq_desc *desc;
struct irqaction **p;
unsigned long flags;
+ irqreturn_t (*handler)(int, void *) = NULL;
WARN_ON(in_interrupt());
if (irq >= NR_IRQS)
@@ -396,6 +397,8 @@
/* Make sure it's not being used on another CPU */
synchronize_irq(irq);
+ if (action->flags & IRQF_SHARED)
+ handler = action->handler;
kfree(action);
return;
}
@@ -403,6 +406,17 @@
spin_unlock_irqrestore(&desc->lock, flags);
return;
}
+#ifdef CONFIG_DEBUG_SHIRQ
+ if (handler) {
+ /*
+ * It's a shared IRQ -- the driver ought to be prepared for it
+ * to happen even now it's being freed, so let's make sure....
+ * We do this after actually deregistering it, to make sure that
+ * a 'real' IRQ doesn't run in parallel with our fake
+ */
+ handler(irq, dev_id);
+ }
+#endif
}
EXPORT_SYMBOL(free_irq);
@@ -475,6 +489,25 @@
select_smp_affinity(irq);
+#ifdef CONFIG_DEBUG_SHIRQ
+ if (irqflags & IRQF_SHARED) {
+ /*
+ * It's a shared IRQ -- the driver ought to be prepared for it
+ * to happen immediately, so let's make sure....
+ * We do this before actually registering it, to make sure that
+ * a 'real' IRQ doesn't run in parallel with our fake
+ */
+ if (irqflags & IRQF_DISABLED) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ handler(irq, dev_id);
+ local_irq_restore(flags);
+ } else
+ handler(irq, dev_id);
+ }
+#endif
+
retval = setup_irq(irq, action);
if (retval)
kfree(action);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 356a5ab..63f04c1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -77,6 +77,15 @@
Say Y here if you are developing drivers or trying to debug and
identify kernel problems.
+config DEBUG_SHIRQ
+ bool "Debug shared IRQ handlers"
+ depends on DEBUG_KERNEL && GENERIC_HARDIRQS
+ help
+ Enable this to generate a spurious interrupt as soon as a shared
+ interrupt handler is registered, and just before one is deregistered.
+ Drivers ought to be able to handle interrupts coming in at those
+ points; some don't and need to be caught.
+
config LOG_BUF_SHIFT
int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
range 12 21