xen: Remove unnecessary arch specific xen irq functions.

Right now xen's use of the x86 and ia64 handle_irq is just bizarre and very
fragile as it is very non-obvious the function exists and is is used by
code out in drivers/....  Luckily using handle_irq is completely unnecessary,
and we can just use the generic irq apis instead.

This still leaves drivers/xen/events.c as a problematic user of the generic
irq apis it has "static struct irq_info irq_info[NR_IRQS]" but that can be
fixed some other time.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
LKML-Reference: <4B7CAAD2.10803@kernel.org>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/ia64/include/asm/xen/events.h

@@ -36,10 +36,6 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)
 	return !(ia64_psr(regs)->i);
 }
 
-static inline void handle_irq(int irq, struct pt_regs *regs)
-{
-	__do_IRQ(irq);
-}
 #define irq_ctx_init(cpu)	do { } while (0)
 
 #endif /* _ASM_IA64_XEN_EVENTS_H */

drivers/xen/events.c

@@ -649,9 +649,13 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 				int bit_idx = __ffs(pending_bits);
 				int port = (word_idx * BITS_PER_LONG) + bit_idx;
 				int irq = evtchn_to_irq[port];
+				struct irq_desc *desc;
 
-				if (irq != -1)
-					handle_irq(irq, regs);
+				if (irq != -1) {
+					desc = irq_to_desc(irq);
+					if (desc)
+						generic_handle_irq_desc(irq, desc);
+				}
 			}
 		}