[PATCH] lockdep: irqtrace subsystem, s390 support

irqtrace support for s390.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 1f93991..78c8e55 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -142,6 +142,7 @@
 		return;
 	}
 
+	trace_hardirqs_on();
 	/* Wait for external, I/O or machine check interrupt. */
 	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_WAIT |
 			PSW_MASK_IO | PSW_MASK_EXT);