From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Thu, 8 Oct 2009 04:44:21 +0000 (-0400)
Subject: Update 386 cmpxchg support
X-Git-Tag: v0.2.3~22
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=e156285068a631eaafa643d9e930b31780468d00;p=userspace-rcu.git

Update 386 cmpxchg support

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/urcu-pointer-static.h b/urcu-pointer-static.h
index 33bfdee..c0533c9 100644
--- a/urcu-pointer-static.h
+++ b/urcu-pointer-static.h
@@ -78,7 +78,10 @@
 		if (!__builtin_constant_p(_new) ||			\
 		    ((_new) != NULL))					\
 			wmb();						\
-		uatomic_cmpxchg(p, _________pold, _________pnew);	\
+		(likely(URCU_CAS_AVAIL()) ?				\
+			(uatomic_cmpxchg(p, _________pold, _________pnew)) : \
+			(compat_uatomic_cmpxchg(p, _________pold,	\
+						_________pnew)))	\
 	})
 
 /**
diff --git a/urcu/uatomic_arch_x86.h b/urcu/uatomic_arch_x86.h
index fccea8e..dfb5876 100644
--- a/urcu/uatomic_arch_x86.h
+++ b/urcu/uatomic_arch_x86.h
@@ -402,7 +402,13 @@ void _uatomic_dec(void *addr, int len)
 #define compat_uatomic_cmpxchg(ptr, old, _new)	uatomic_cmpxchg(ptr, old, _new)
 #else
 extern int __urcu_cas_avail;
-#define URCU_CAS_AVAIL()	__urcu_cas_avail
+extern int __urcu_cas_init(void);
+#define URCU_CAS_AVAIL()						\
+		((likely(__urcu_cas_avail > 0)) ?			\
+			(1) :						\
+			((unlikely(__urcu_cas_avail < 0) ? 		\
+				(__urcu_cas_init()) :			\
+				(0))))
 
 extern unsigned long _compat_uatomic_cmpxchg(void *addr, unsigned long old,
 			      unsigned long _new, int len);