[PATCH v2] powerpc: handle simultaneous interrupts at once

[Christophe Leroy <christophe.leroy@c-s.fr>]

It often happens to have simultaneous interrupts, for instance
when having double Ethernet attachment. With the current
implementation, we suffer the cost of kernel entry/exit for each
interrupt.

This patch introduces a loop in __do_irq() to handle all interrupts
at once before returning.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
Changed from v1(RFC): simplified following remark from benh

 arch/powerpc/kernel/irq.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index a018f5cae899..ba0cb6c2ee7d 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -522,7 +522,11 @@ void __do_irq(struct pt_regs *regs)
 	if (unlikely(!irq))
 		__this_cpu_inc(irq_stat.spurious_irqs);
 	else
-		generic_handle_irq(irq);
+		do {
+			generic_handle_irq(irq);
+
+			irq = ppc_md.get_irq();
+		} while (irq);
 
 	trace_irq_exit(regs);
 
-- 
2.12.0