[PATCH libxshmfence] Add support for FreeBSD using umtx (v3).

[Jung-uk Kim]

This fixes a sign-extension bug in the previous versions.

Signed-off-by: Jung-uk Kim <jkim at FreeBSD.org>
---
 configure.ac          | 11 ++++++++++-
 src/xshmfence_futex.h | 24 ++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 8a39f22..64fb0cc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -54,7 +54,16 @@ AC_ARG_ENABLE(futex,	AS_HELP_STRING([--enable-futex], [Enable futexes (default:
 		[FUTEX=$enableval], [FUTEX=auto])
 
 if test "x$FUTEX" = "xauto"; then
-	AC_CHECK_HEADER([linux/futex.h], [FUTEX=yes], [FUTEX=no])
+	AC_CHECK_HEADER([linux/futex.h], [FUTEX=yes])
+fi
+
+if test "x$FUTEX" = "xauto"; then
+	AC_CHECK_HEADER([sys/umtx.h], [FUTEX=yes], [FUTEX=no],
+	    [#include <errno.h>
+	     #include <sys/types.h>])
+	if test "x$FUTEX" = "xyes"; then
+		AC_DEFINE(HAVE_UMTX, 1, [Use umtx])
+	fi
 fi
 
 if test "x$FUTEX" = "xyes"; then
diff --git a/src/xshmfence_futex.h b/src/xshmfence_futex.h
index ed60b6d..210e069 100644
--- a/src/xshmfence_futex.h
+++ b/src/xshmfence_futex.h
@@ -1,5 +1,6 @@
 /*
  * Copyright © 2013 Keith Packard
+ * Copyright © 2013 Jung-uk Kim <jkim at FreeBSD.org>
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
@@ -24,6 +25,27 @@
 #define _XSHMFENCE_FUTEX_H_
 
 #include <errno.h>
+
+#ifdef HAVE_UMTX
+
+#include <sys/types.h>
+#include <sys/umtx.h>
+
+static inline int sys_futex(void *addr, int op, int32_t val)
+{
+	return _umtx_op(addr, op, (uint32_t)val, NULL, NULL) == -1 ? errno : 0;
+}
+
+static inline int futex_wake(int32_t *addr) {
+	return sys_futex(addr, UMTX_OP_WAKE, INT_MAX);
+}
+
+static inline int futex_wait(int32_t *addr, int32_t value) {
+	return sys_futex(addr, UMTX_OP_WAIT_UINT, value);
+}
+
+#else
+
 #include <stdint.h>
 #include <values.h>
 #include <linux/futex.h>
@@ -43,6 +65,8 @@ static inline int futex_wait(int32_t *addr, int32_t value) {
 	return sys_futex(addr, FUTEX_WAIT, value, NULL, NULL, 0);
 }
 
+#endif
+
 #define barrier() __asm__ __volatile__("": : :"memory")
 
 static inline void atomic_store(int32_t *f, int32_t v)
-- 
1.8.4.3