lockdep: warn about lockdep disabling after kernel taint, fix

Impact: build fix for Sparc and s390

Stephen Rothwell reported that the Sparc build broke:

 In file included from kernel/panic.c:12:
 include/linux/debug_locks.h: In function '__debug_locks_off':
 include/linux/debug_locks.h:15: error: implicit declaration of function 'xchg'

due to:

 9eeba61: lockdep: warn about lockdep disabling after kernel taint

There is some inconsistency between architectures about where exactly
xchg() is defined.

The traditional place is in system.h but the more logical point for it
is in atomic.h - where most architectures (especially new ones) have
it defined. These architecture also still offer it via system.h.

Some, such as Sparc or s390 only have it in asm/system.h and not available
via asm/atomic.h at all.

Use the widest set of headers in debug_locks.h and also include asm/system.h.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090414144317.026498df.sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index 493dedb7a67..29b3ce3f2a1 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -3,6 +3,7 @@
 
 #include <linux/kernel.h>
 #include <asm/atomic.h>
+#include <asm/system.h>
 
 struct task_struct;