add a helper function to test if an object is on the stack

lib/debugobjects.c has a function to test if an object is on the stack.
The block layer and ide needs it (they need to avoid DMA from/to stack
buffers).  This patch moves the function to include/linux/sched.h so that
everyone can use it.

lib/debugobjects.c uses current->stack but this patch uses a
task_stack_page() accessor, which is a preferable way to access the stack.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 3 deletions

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 85b18d79be89..f86196390cfd 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -226,15 +226,13 @@ debug_object_fixup(int (*fixup)(void *addr, enum debug_obj_state state),
 
 static void debug_object_is_on_stack(void *addr, int onstack)
 {
-        void *stack = current->stack;
         int is_on_stack;
         static int limit;
 
         if (limit > 4)
                 return;
 
-        is_on_stack = (addr >= stack && addr < (stack + THREAD_SIZE));
-
+        is_on_stack = object_is_on_stack(addr);
         if (is_on_stack == onstack)
                 return;