X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=urcu%2Ffutex.h;h=7f175645f2b27d22a5d6358815870a80fc84fd36;hb=refs%2Fheads%2Fstable-0.8;hp=cdaa430003ad6dfca0f5d7537ff4a1d021889a7e;hpb=dcd64e8a1530e57571fa2230ebb9dd3fa6c65366;p=userspace-rcu.git

diff --git a/urcu/futex.h b/urcu/futex.h
index cdaa430..7f17564 100644
--- a/urcu/futex.h
+++ b/urcu/futex.h
@@ -42,24 +42,80 @@ extern "C" {
  *
  * futex_async is signal-handler safe for the wakeup. It uses polling
  * on the wait-side in compatibility mode.
+ *
+ * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
+ * (returns EINTR).
  */
 
+extern int compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3);
+extern int compat_futex_async(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3);
+
 #ifdef CONFIG_RCU_HAVE_FUTEX
+
+#include <unistd.h>
+#include <errno.h>
+#include <urcu/compiler.h>
 #include <syscall.h>
-#define futex(...)	syscall(__NR_futex, __VA_ARGS__)
-#define futex_noasync(uaddr, op, val, timeout, uaddr2, val3)	\
-		futex(uaddr, op, val, timeout, uaddr2, val3)
-#define futex_async(uaddr, op, val, timeout, uaddr2, val3)	\
-		futex(uaddr, op, val, timeout, uaddr2, val3)
+
+static inline int futex(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	return syscall(__NR_futex, uaddr, op, val, timeout,
+			uaddr2, val3);
+}
+
+static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	int ret;
+
+	ret = futex(uaddr, op, val, timeout, uaddr2, val3);
+	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
+		/*
+		 * The fallback on ENOSYS is the async-safe version of
+		 * the compat futex implementation, because the
+		 * async-safe compat implementation allows being used
+		 * concurrently with calls to futex(). Indeed, sys_futex
+		 * FUTEX_WAIT, on some architectures (mips and parisc),
+		 * within a given process, spuriously return ENOSYS due
+		 * to signal restart bugs on some kernel versions.
+		 */
+		return compat_futex_async(uaddr, op, val, timeout,
+				uaddr2, val3);
+	}
+	return ret;
+
+}
+
+static inline int futex_async(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	int ret;
+
+	ret = futex(uaddr, op, val, timeout, uaddr2, val3);
+	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
+		return compat_futex_async(uaddr, op, val, timeout,
+				uaddr2, val3);
+	}
+	return ret;
+}
+
 #else
-extern int compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
-	const struct timespec *timeout, int32_t *uaddr2, int32_t val3);
-#define futex_noasync(uaddr, op, val, timeout, uaddr2, val3)	\
-		compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3)
-extern int compat_futex_async(int32_t *uaddr, int op, int32_t val,
-	const struct timespec *timeout, int32_t *uaddr2, int32_t val3);
-#define futex_async(uaddr, op, val, timeout, uaddr2, val3)	\
-		compat_futex_async(uaddr, op, val, timeout, uaddr2, val3)
+
+static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	return compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3);
+}
+
+static inline int futex_async(int32_t *uaddr, int op, int32_t val,
+		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
+}
+
 #endif
 
 #ifdef __cplusplus