2006-02-08 06:44:34

by Chris Wright

[permalink] [raw]
Subject: [PATCH 23/23] [alpha] __cmpxchg() must really always be inlined

-stable review patch. If anyone has any objections, please let us know.
------------------

With the latest 2.6.15 kernel builds for alpha on Debian, we ran into a
problem with undefined references to __cmpxchg_called_with_bad_pointer() in
a couple of kernel modules (xfs.ko and drm.ko; see
http://bugs.debian.org/347556).

It looks like people have been trying to out-clever each other wrt the
definition of "inline" on this architecture :), with the result that
__cmpxchg(), which must be inlined so the compiler can see its argument is
const, is not guaranteed to be inlined. Indeed, it was not being inlined
when building with -Os.

The attached patch fixes the issue by adding an
__attribute__((always_inline)) explicitly to the definition of __cmpxchg()
instead of relying on redefines of "inline" elsewhere to make this happen.

Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---

include/asm-alpha/system.h | 2 +-
1 files changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.15.3.orig/include/asm-alpha/system.h
+++ linux-2.6.15.3/include/asm-alpha/system.h
@@ -562,7 +562,7 @@ __cmpxchg_u64(volatile long *m, unsigned
if something tries to do an invalid cmpxchg(). */
extern void __cmpxchg_called_with_bad_pointer(void);

-static inline unsigned long
+static __always_inline unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
{
switch (size) {

--