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Subject[PATCH -rt][RESEND] fix preempt hardirqs on OMAP
This should fix hardirq threading when the chained handler disables an interrupt 
while setting IRQ_PENDING. Which happens on ARM OMAP. It also has the effect of
re-running the interrupt on IRQ_PENDING, which would normally be handled inside
the chained handler. Since this happens inside a thread the chained handler will
just wake up the thread multiple times, leaving the thread to actually rerun the
interrupt.

Signed-Off-By: Daniel Walker <dwalker@mvista.com>

---
kernel/irq/manage.c | 14 ++++++++++++++
1 files changed, 14 insertions(+)

Index: linux-2.6.19/kernel/irq/manage.c
===================================================================
--- linux-2.6.19.orig/kernel/irq/manage.c
+++ linux-2.6.19/kernel/irq/manage.c
@@ -546,6 +546,7 @@ static void thread_simple_irq(irq_desc_t
unsigned int irq = desc - irq_desc;
irqreturn_t action_ret;

+restart:
if (action && !desc->depth) {
spin_unlock(&desc->lock);
action_ret = handle_IRQ_event(irq, action);
@@ -555,6 +556,19 @@ static void thread_simple_irq(irq_desc_t
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
}
+
+ /*
+ * Some boards will disable an interrupt when it
+ * sets IRQ_PENDING . So we have to remove the flag
+ * and re-enable to handle it.
+ */
+ if (desc->status & IRQ_PENDING) {
+ desc->status &= ~IRQ_PENDING;
+ if (desc->chip)
+ desc->chip->enable(irq);
+ goto restart;
+ }
+
desc->status &= ~IRQ_INPROGRESS;
}

--
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