[PATCH v4] Use _umtx_op for futex on FreeBSD

["Alex Xu \(Hello71\) via lttng-dev" <lttng-dev@lists.lttng.org>]

Tested with "make check", "make regtest" and a knotd slave.
---
 include/urcu/futex.h | 45 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/include/urcu/futex.h b/include/urcu/futex.h
index c206c6f..0777d95 100644
--- a/include/urcu/futex.h
+++ b/include/urcu/futex.h
@@ -24,6 +24,7 @@
  */
 
 #include <urcu/config.h>
+#include <errno.h>
 #include <stdint.h>
 #include <time.h>
 
@@ -103,6 +104,50 @@ static inline int futex_async(int32_t *uaddr, int op, int32_t val,
 	return ret;
 }
 
+#elif defined(__FreeBSD__)
+
+#include <sys/types.h>
+#include <sys/umtx.h>
+
+static inline int futex_async(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	int umtx_op;
+	void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL;
+	struct _umtx_time umtx_timeout = {
+		._flags = UMTX_ABSTIME,
+		._clockid = CLOCK_MONOTONIC
+	};
+
+	switch (op) {
+		case FUTEX_WAIT:
+			// on FreeBSD, a "u_int" is a 32-bit integer
+			umtx_op = UMTX_OP_WAIT_UINT;
+			if (timeout != NULL) {
+				umtx_timeout._timeout = *timeout;
+				umtx_uaddr = (void *)sizeof(umtx_timeout);
+				umtx_uaddr2 = (void *)&umtx_timeout;
+			}
+			break;
+
+		case FUTEX_WAKE:
+			umtx_op = UMTX_OP_WAKE;
+			break;
+
+		default:
+			errno = EINVAL;
+			return -1;
+	}
+
+	return _umtx_op(uaddr, umtx_op, (uint32_t)val, umtx_uaddr, umtx_uaddr2);
+}
+
+static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	return futex_async(uaddr, op, val, timeout, uaddr2, val3);
+}
+
 #elif defined(__CYGWIN__)
 
 /*
-- 
2.25.0