[linux-2.6-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

/*
 * 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

/*
 * Reserved bit:
 */
#define FUTEX_OWNER_PENDING	0x20000000

/*
 * The rest of the robust-futex field is for the TID:
 */
#define FUTEX_TID_MASK		0x1fffffff

/*
 * A limit of one million locks held per thread (!) ought to be enough
 * for some time. This also protects against a deliberately circular
 * list. Not worth introducing an rlimit for this:
 */
#define ROBUST_LIST_LIMIT	1048576

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

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

#ifdef CONFIG_FUTEX
extern void exit_robust_list(struct task_struct *curr);
#else
static inline void exit_robust_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
1da177e4	15
0771dfef IM	16	/*
	17	* Support for robust futexes: the kernel cleans up held futexes at
	18	* thread exit time.
	19	*/
	20
	21	/*
	22	* Per-lock list entry - embedded in user-space locks, somewhere close
	23	* to the futex field. (Note: user-space uses a double-linked list to
	24	* achieve O(1) list add and remove, but the kernel only needs to know
	25	* about the forward link)
	26	*
	27	* NOTE: this structure is part of the syscall ABI, and must not be
	28	* changed.
	29	*/
	30	struct robust_list {
	31	struct robust_list __user *next;
	32	};
	33
	34	/*
	35	* Per-thread list head:
	36	*
	37	* NOTE: this structure is part of the syscall ABI, and must only be
	38	* changed if the change is first communicated with the glibc folks.
	39	* (When an incompatible change is done, we'll increase the structure
	40	* size, which glibc will detect)
	41	*/
	42	struct robust_list_head {
	43	/*
	44	* The head of the list. Points back to itself if empty:
	45	*/
	46	struct robust_list list;
	47
	48	/*
	49	* This relative offset is set by user-space, it gives the kernel
	50	* the relative position of the futex field to examine. This way
	51	* we keep userspace flexible, to freely shape its data-structure,
	52	* without hardcoding any particular offset into the kernel:
	53	*/
	54	long futex_offset;
	55
	56	/*
	57	* The death of the thread may race with userspace setting
	58	* up a lock's links. So to handle this race, userspace first
	59	* sets this field to the address of the to-be-taken lock,
	60	* then does the lock acquire, and then adds itself to the
	61	* list, and then clears this field. Hence the kernel will
	62	* always have full knowledge of all locks that the thread
	63	* _might_ have taken. We check the owner TID in any case,
	64	* so only truly owned locks will be handled.
	65	*/
	66	struct robust_list __user *list_op_pending;
	67	};
	68
	69	/*
	70	* Are there any waiters for this robust futex:
	71	*/
	72	#define FUTEX_WAITERS 0x80000000
	73
	74	/*
	75	* The kernel signals via this bit that a thread holding a futex
	76	* has exited without unlocking the futex. The kernel also does
	77	* a FUTEX_WAKE on such futexes, after setting the bit, to wake
	78	* up any possible waiters:
	79	*/
80	#define FUTEX_OWNER_DIED 0x40000000
81
82	/*
83	* Reserved bit:
84	*/
85	#define FUTEX_OWNER_PENDING 0x20000000
86
87	/*
88	* The rest of the robust-futex field is for the TID:
89	*/
90	#define FUTEX_TID_MASK 0x1fffffff
91
92	/*
93	* A limit of one million locks held per thread (!) ought to be enough
94	* for some time. This also protects against a deliberately circular
95	* list. Not worth introducing an rlimit for this:
96	*/
97	#define ROBUST_LIST_LIMIT 1048576
98
1da177e4 LT	99	long do_futex(unsigned long uaddr, int op, int val,
	100	unsigned long timeout, unsigned long uaddr2, int val2,
	101	int val3);
	102
0771dfef IM	103	extern int handle_futex_death(unsigned int uaddr, struct task_struct curr);
	104
	105	#ifdef CONFIG_FUTEX
	106	extern void exit_robust_list(struct task_struct *curr);
	107	#else
	108	static inline void exit_robust_list(struct task_struct *curr)
	109	{
	110	}
	111	#endif
	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