X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Ffutex.h;h=0486ff6a1830f174d7471164a282507a6d1f756c;hp=906d9b723ae88481fc7874e1409dc24dd80f35eb;hb=b2633d211b186cb201be327ded53ecf523ecf0bd;hpb=3282a76b46b74a92809292fa63ba671de9ad88eb

diff --git a/urcu/futex.h b/urcu/futex.h
index 906d9b7..0486ff6 100644
--- a/urcu/futex.h
+++ b/urcu/futex.h
@@ -28,7 +28,7 @@
 
 #ifdef __cplusplus
 extern "C" {
-#endif 
+#endif
 
 #define FUTEX_WAIT		0
 #define FUTEX_WAKE		1
@@ -42,27 +42,83 @@ 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).
  */
 
-#ifdef CONFIG_RCU_HAVE_FUTEX
-#include <sys/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)
-#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)
+		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);
-#define futex_async(uaddr, op, val, timeout, uaddr2, val3)	\
-		compat_futex_async(uaddr, op, val, timeout, uaddr2, val3)
+		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 <urcu/arch.h>
+
+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
+
+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 
+#ifdef __cplusplus
 }
 #endif