Document that IRQ_NONE should be returned when IRQ not actually handled

Our IRQ storm detection works when an interrupt handler returns
IRQ_NONE for thousands of consecutive interrupts in a second. It
doesn't hurt to occasionally return IRQ_NONE when the interrupt is
actually genuine.

Drivers should only be returning IRQ_HANDLED if they have actually
*done* something to stop an interrupt from happening — it doesn't just
mean "this really *was* my device".

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: davem@davemloft.net
Link: http://lkml.kernel.org/r/1446016471.3405.201.camel@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/irqreturn.h b/include/linux/irqreturn.h
index e374e369fb2f4c9eb5ace48679376550d5ee633c..eb1bdcf95f2e0c931a3a5cb599ab06547ff34f3d 100644 (file)
--- a/include/linux/irqreturn.h
+++ b/include/linux/irqreturn.h
@@ -3,7 +3,7 @@
 
 /**
  * enum irqreturn
- * @IRQ_NONE           interrupt was not from this device
+ * @IRQ_NONE           interrupt was not from this device or was not handled
  * @IRQ_HANDLED                interrupt was handled by this device
  * @IRQ_WAKE_THREAD    handler requests to wake the handler thread
  */