futex: implementation of WM (wait multiple)

include/uapi/linux/futex.h

@@ -21,6 +21,7 @@
 #define FUTEX_WAKE_BITSET	10
 #define FUTEX_WAIT_REQUEUE_PI	11
 #define FUTEX_CMP_REQUEUE_PI	12
+#define FUTEX_WAIT_MULTIPLE		31
 
 #define FUTEX_PRIVATE_FLAG	128
 #define FUTEX_CLOCK_REALTIME	256
@@ -41,59 +42,6 @@
 #define FUTEX_CMP_REQUEUE_PI_PRIVATE	(FUTEX_CMP_REQUEUE_PI | \
 					 FUTEX_PRIVATE_FLAG)
 
-/*
- * Support for robust futexes: the kernel cleans up held futexes at
- * thread exit time.
- */
-
-/*
- * Per-lock list entry - embedded in user-space locks, somewhere close
- * to the futex field. (Note: user-space uses a double-linked list to
- * achieve O(1) list add and remove, but the kernel only needs to know
- * about the forward link)
- *
- * NOTE: this structure is part of the syscall ABI, and must not be
- * changed.
- */
-struct robust_list {
-	struct robust_list __user *next;
-};
-
-/*
- * Per-thread list head:
- *
- * NOTE: this structure is part of the syscall ABI, and must only be
- * changed if the change is first communicated with the glibc folks.
- * (When an incompatible change is done, we'll increase the structure
- *  size, which glibc will detect)
- */
-struct robust_list_head {
-	/*
-	 * The head of the list. Points back to itself if empty:
-	 */
-	struct robust_list list;
-
-	/*
-	 * This relative offset is set by user-space, it gives the kernel
-	 * the relative position of the futex field to examine. This way
-	 * we keep userspace flexible, to freely shape its data-structure,
-	 * without hardcoding any particular offset into the kernel:
-	 */
-	long futex_offset;
-
-	/*
-	 * The death of the thread may race with userspace setting
-	 * up a lock's links. So to handle this race, userspace first
-	 * sets this field to the address of the to-be-taken lock,
-	 * then does the lock acquire, and then adds itself to the
-	 * list, and then clears this field. Hence the kernel will
-	 * always have full knowledge of all locks that the thread
-	 * _might_ have taken. We check the owner TID in any case,
-	 * so only truly owned locks will be handled.
-	 */
-	struct robust_list __user *list_op_pending;
-};
-
 /*
  * Are there any waiters for this robust futex:
  */
@@ -150,4 +98,68 @@ struct robust_list_head {
   (((op & 0xf) << 28) | ((cmp & 0xf) << 24)		\
    | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
 
+/*
+ * Include here the ASM files so all required defs are present 
+ */
+#include <asm/futex.h>
+
+/*
+ * Support for robust futexes: the kernel cleans up held futexes at
+ * thread exit time.
+ */
+
+/*
+ * Per-lock list entry - embedded in user-space locks, somewhere close
+ * to the futex field. (Note: user-space uses a double-linked list to
+ * achieve O(1) list add and remove, but the kernel only needs to know
+ * about the forward link)
+ *
+ * NOTE: this structure is part of the syscall ABI, and must not be
+ * changed.
+ */
+struct robust_list {
+	struct robust_list __user *next;
+};
+
+/*
+ * Per-thread list head:
+ *
+ * NOTE: this structure is part of the syscall ABI, and must only be
+ * changed if the change is first communicated with the glibc folks.
+ * (When an incompatible change is done, we'll increase the structure
+ *  size, which glibc will detect)
+ */
+struct robust_list_head {
+	/*
+	 * The head of the list. Points back to itself if empty:
+	 */
+	struct robust_list list;
+
+	/*
+	 * This relative offset is set by user-space, it gives the kernel
+	 * the relative position of the futex field to examine. This way
+	 * we keep userspace flexible, to freely shape its data-structure,
+	 * without hardcoding any particular offset into the kernel:
+	 */
+	long futex_offset;
+
+	/*
+	 * The death of the thread may race with userspace setting
+	 * up a lock's links. So to handle this race, userspace first
+	 * sets this field to the address of the to-be-taken lock,
+	 * then does the lock acquire, and then adds itself to the
+	 * list, and then clears this field. Hence the kernel will
+	 * always have full knowledge of all locks that the thread
+	 * _might_ have taken. We check the owner TID in any case,
+	 * so only truly owned locks will be handled.
+	 */
+	struct robust_list __user *list_op_pending;
+};
+
+struct futex_wait_block {
+	__u32 __user *uaddr;
+	__u32 val;
+	__u32 bitset;
+};
+
 #endif /* _UAPI_LINUX_FUTEX_H */

kernel/futex.c

@@ -40,8 +40,7 @@
 #include <linux/memblock.h>
 #include <linux/fault-inject.h>
 #include <linux/time_namespace.h>
-
-#include <asm/futex.h>
+#include <linux/futex.h>
 
 #include "locking/rtmutex_common.h"
 
@@ -166,10 +165,8 @@ static int  __read_mostly futex_cmpxchg_enabled;
 #endif
 #define FLAGS_CLOCKRT		0x02
 #define FLAGS_HAS_TIMEOUT	0x04
-<<<<<<< HEAD
 #define FLAGS_WAKE_MULTIPLE	0x08
-=======
- */
+
 struct futex_pi_state {
 	/*
 	 * list of 'owned' pi_state instances - these have to be