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Diffstat (limited to 'arch/ia64/include/uapi/asm/cmpxchg.h')
-rw-r--r--arch/ia64/include/uapi/asm/cmpxchg.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/ia64/include/uapi/asm/cmpxchg.h b/arch/ia64/include/uapi/asm/cmpxchg.h
index 4f37dbbb8640..f35109b1d907 100644
--- a/arch/ia64/include/uapi/asm/cmpxchg.h
+++ b/arch/ia64/include/uapi/asm/cmpxchg.h
@@ -118,6 +118,15 @@ extern long ia64_cmpxchg_called_with_bad_pointer(void);
#define cmpxchg_rel(ptr, o, n) \
ia64_cmpxchg(rel, (ptr), (o), (n), sizeof(*(ptr)))
+/*
+ * Worse still - early processor implementations actually just ignored
+ * the acquire/release and did a full fence all the time. Unfortunately
+ * this meant a lot of badly written code that used .acq when they really
+ * wanted .rel became legacy out in the wild - so when we made a cpu
+ * that strictly did the .acq or .rel ... all that code started breaking - so
+ * we had to back-pedal and keep the "legacy" behavior of a full fence :-(
+ */
+
/* for compatibility with other platforms: */
#define cmpxchg(ptr, o, n) cmpxchg_acq((ptr), (o), (n))
#define cmpxchg64(ptr, o, n) cmpxchg_acq((ptr), (o), (n))