[PATCH] lockdep: forward declare struct task_struct

3117df0453828bd045c16244e6f50e5714667a8a causes this:

In file included from arch/s390/kernel/early.c:13:
include/linux/lockdep.h:300: warning:
		"struct task_struct" declared inside parameter list
include/linux/lockdep.h:300:
		warning: its scope is only this definition or
		declaration, which is probably not what you want

Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 7e1160d..06fe93a 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -8,6 +8,8 @@
 #ifndef __LINUX_LOCKDEP_H
 #define __LINUX_LOCKDEP_H
 
+struct task_struct;
+
 #ifdef CONFIG_LOCKDEP
 
 #include <linux/linkage.h>