[PATCH] genirq: fix irq flow handler uninstall

The sanity check for no_irq_chip in __set_irq_hander() is unconditional on
both install and uninstall of an handler.  This triggers false warnings and
replaces no_irq_chip by dummy_irq_chip in the uninstall case.

Check only, when a real handler is installed.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NSylvain Munaut <tnt@246tNt.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

kernel/irq/chip.c

@@ -517,8 +517,7 @@ __set_irq_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
 
 	if (!handle)
 		handle = handle_bad_irq;
-
-	if (desc->chip == &no_irq_chip) {
+	else if (desc->chip == &no_irq_chip) {
 		printk(KERN_WARNING "Trying to install %sinterrupt handler "
 		       "for IRQ%d\n", is_chained ? "chained " : "", irq);
 		/*