[patch] __cmpxchg() must really always be inlined on alpha

[patch] __cmpxchg() must really always be inlined on alpha

[Steve Langasek]

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Hi folks,

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.

I was asked to forward the attached patch to these two lists, which 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.  Please let me know if I should be submitting
the patch in a different format.

Thanks,
-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
vorlon@debian.org                                   http://www.debian.org/

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--- linux-2.6.15/include/asm-alpha/system.h.orig	2006-01-26 02:57:09.000000000 -0800
+++ linux-2.6.15/include/asm-alpha/system.h	2006-01-26 02:58:13.000000000 -0800
@@ -562,7 +562,7 @@
    if something tries to do an invalid cmpxchg().  */
 extern void __cmpxchg_called_with_bad_pointer(void);
 
-static inline unsigned long
+static inline __attribute__((always_inline)) unsigned long
 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
 {
 	switch (size) {

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