s390/irq: select HAVE_IRQ_EXIT_ON_IRQ_STACK

irq_exit() is always called on async stack. Therefore select
HAVE_IRQ_EXIT_ON_IRQ_STACK and get a tiny optimization in
invoke_softirq().

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a60cc52..9e8895c 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -153,6 +153,7 @@ config S390
        select HAVE_FUTEX_CMPXCHG if FUTEX
        select HAVE_GCC_PLUGINS
        select HAVE_GENERIC_VDSO
+       select HAVE_IRQ_EXIT_ON_IRQ_STACK
        select HAVE_KERNEL_BZIP2
        select HAVE_KERNEL_GZIP
        select HAVE_KERNEL_LZ4