[linux-block.git] / include / linux / futex.h

#ifndef _LINUX_FUTEX_H
#define _LINUX_FUTEX_H

#include <linux/sched.h>

/* Second argument to futex syscall */


#define FUTEX_WAIT		0
#define FUTEX_WAKE		1
#define FUTEX_FD		2
#define FUTEX_REQUEUE		3
#define FUTEX_CMP_REQUEUE	4
#define FUTEX_WAKE_OP		5
#define FUTEX_LOCK_PI		6
#define FUTEX_UNLOCK_PI		7
#define FUTEX_TRYLOCK_PI	8

/*
 * 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:
 */
#define FUTEX_WAITERS		0x80000000

/*
 * The kernel signals via this bit that a thread holding a futex
 * has exited without unlocking the futex. The kernel also does
 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
 * up any possible waiters:
 */
#define FUTEX_OWNER_DIED	0x40000000

/*
 * The rest of the robust-futex field is for the TID:
 */
#define FUTEX_TID_MASK		0x3fffffff

/*
 * This limit protects against a deliberately circular list.
 * (Not worth introducing an rlimit for it)
 */
#define ROBUST_LIST_LIMIT	2048

long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
	      u32 __user *uaddr2, u32 val2, u32 val3);

extern int handle_futex_death(u32 __user *uaddr, struct task_struct *curr);

#ifdef CONFIG_FUTEX
extern void exit_robust_list(struct task_struct *curr);
extern void exit_pi_state_list(struct task_struct *curr);
#else
static inline void exit_robust_list(struct task_struct *curr)
{
}
static inline void exit_pi_state_list(struct task_struct *curr)
{
}
#endif

#define FUTEX_OP_SET		0	/* *(int *)UADDR2 = OPARG; */
#define FUTEX_OP_ADD		1	/* *(int *)UADDR2 += OPARG; */
#define FUTEX_OP_OR		2	/* *(int *)UADDR2 |= OPARG; */
#define FUTEX_OP_ANDN		3	/* *(int *)UADDR2 &= ~OPARG; */
#define FUTEX_OP_XOR		4	/* *(int *)UADDR2 ^= OPARG; */

#define FUTEX_OP_OPARG_SHIFT	8	/* Use (1 << OPARG) instead of OPARG.  */

#define FUTEX_OP_CMP_EQ		0	/* if (oldval == CMPARG) wake */
#define FUTEX_OP_CMP_NE		1	/* if (oldval != CMPARG) wake */
#define FUTEX_OP_CMP_LT		2	/* if (oldval < CMPARG) wake */
#define FUTEX_OP_CMP_LE		3	/* if (oldval <= CMPARG) wake */
#define FUTEX_OP_CMP_GT		4	/* if (oldval > CMPARG) wake */
#define FUTEX_OP_CMP_GE		5	/* if (oldval >= CMPARG) wake */

/* FUTEX_WAKE_OP will perform atomically
   int oldval = *(int *)UADDR2;
   *(int *)UADDR2 = oldval OP OPARG;
   if (oldval CMP CMPARG)
     wake UADDR2;  */

#define FUTEX_OP(op, oparg, cmp, cmparg) \
  (((op & 0xf) << 28) | ((cmp & 0xf) << 24)		\
   | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))

#endif
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_FUTEX_H
	2	#define _LINUX_FUTEX_H
	3
0771dfef IM	4	#include <linux/sched.h>
0771dfef IM	5
1da177e4 LT	6	/* Second argument to futex syscall */
	7
	8
4732efbe JJ	9	#define FUTEX_WAIT 0
	10	#define FUTEX_WAKE 1
	11	#define FUTEX_FD 2
	12	#define FUTEX_REQUEUE 3
	13	#define FUTEX_CMP_REQUEUE 4
	14	#define FUTEX_WAKE_OP 5
c87e2837 IM	15	#define FUTEX_LOCK_PI 6
	16	#define FUTEX_UNLOCK_PI 7
	17	#define FUTEX_TRYLOCK_PI 8
1da177e4	18
0771dfef IM	19	/*
	20	* Support for robust futexes: the kernel cleans up held futexes at
	21	* thread exit time.
	22	*/
	23
	24	/*
	25	* Per-lock list entry - embedded in user-space locks, somewhere close
	26	* to the futex field. (Note: user-space uses a double-linked list to
	27	* achieve O(1) list add and remove, but the kernel only needs to know
	28	* about the forward link)
	29	*
	30	* NOTE: this structure is part of the syscall ABI, and must not be
	31	* changed.
	32	*/
	33	struct robust_list {
	34	struct robust_list __user *next;
	35	};
	36
	37	/*
	38	* Per-thread list head:
	39	*
	40	* NOTE: this structure is part of the syscall ABI, and must only be
	41	* changed if the change is first communicated with the glibc folks.
	42	* (When an incompatible change is done, we'll increase the structure
	43	* size, which glibc will detect)
	44	*/
	45	struct robust_list_head {
	46	/*
	47	* The head of the list. Points back to itself if empty:
	48	*/
	49	struct robust_list list;
	50
	51	/*
	52	* This relative offset is set by user-space, it gives the kernel
	53	* the relative position of the futex field to examine. This way
	54	* we keep userspace flexible, to freely shape its data-structure,
	55	* without hardcoding any particular offset into the kernel:
	56	*/
	57	long futex_offset;
	58
	59	/*
	60	* The death of the thread may race with userspace setting
	61	* up a lock's links. So to handle this race, userspace first
	62	* sets this field to the address of the to-be-taken lock,
	63	* then does the lock acquire, and then adds itself to the
	64	* list, and then clears this field. Hence the kernel will
	65	* always have full knowledge of all locks that the thread
	66	* _might_ have taken. We check the owner TID in any case,
	67	* so only truly owned locks will be handled.
	68	*/
	69	struct robust_list __user *list_op_pending;
	70	};
	71
	72	/*
	73	* Are there any waiters for this robust futex:
	74	*/
	75	#define FUTEX_WAITERS 0x80000000
	76
	77	/*
	78	* The kernel signals via this bit that a thread holding a futex
	79	* has exited without unlocking the futex. The kernel also does
	80	* a FUTEX_WAKE on such futexes, after setting the bit, to wake
	81	* up any possible waiters:
	82	*/
83	#define FUTEX_OWNER_DIED 0x40000000
84
0771dfef IM	85	/*
	86	* The rest of the robust-futex field is for the TID:
	87	*/
76b81e2b	88	#define FUTEX_TID_MASK 0x3fffffff
0771dfef IM	89
0771dfef IM	90	/*
76b81e2b IM	91	* This limit protects against a deliberately circular list.
76b81e2b IM	92	* (Not worth introducing an rlimit for it)
0771dfef	93	*/
76b81e2b	94	#define ROBUST_LIST_LIMIT 2048
0771dfef	95
e2970f2f IM	96	long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
e2970f2f IM	97	u32 __user *uaddr2, u32 val2, u32 val3);
1da177e4	98
8f17d3a5	99	extern int handle_futex_death(u32 __user uaddr, struct task_struct curr);
0771dfef IM	100
	101	#ifdef CONFIG_FUTEX
	102	extern void exit_robust_list(struct task_struct *curr);
c87e2837	103	extern void exit_pi_state_list(struct task_struct *curr);
0771dfef IM	104	#else
	105	static inline void exit_robust_list(struct task_struct *curr)
	106	{
	107	}
c87e2837 IM	108	static inline void exit_pi_state_list(struct task_struct *curr)
	109	{
	110	}
0771dfef IM	111	#endif
0771dfef IM	112
4732efbe JJ	113	#define FUTEX_OP_SET 0 /* (int )UADDR2 = OPARG; */
	114	#define FUTEX_OP_ADD 1 /* (int )UADDR2 += OPARG; */
	115	#define FUTEX_OP_OR 2 /* (int )UADDR2 \|= OPARG; */
	116	#define FUTEX_OP_ANDN 3 /* (int )UADDR2 &= ~OPARG; */
	117	#define FUTEX_OP_XOR 4 /* (int )UADDR2 ^= OPARG; */
	118
	119	#define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
	120
	121	#define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
	122	#define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
	123	#define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
	124	#define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
	125	#define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
	126	#define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
	127
	128	/* FUTEX_WAKE_OP will perform atomically
	129	int oldval = (int )UADDR2;
	130	(int )UADDR2 = oldval OP OPARG;
	131	if (oldval CMP CMPARG)
	132	wake UADDR2; */
	133
	134	#define FUTEX_OP(op, oparg, cmp, cmparg) \
	135	(((op & 0xf) << 28) \| ((cmp & 0xf) << 24) \
	136	\| ((oparg & 0xfff) << 12) \| (cmparg & 0xfff))
	137
1da177e4	138	#endif