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

#ifndef _LINUX_FUTEX_H
#define _LINUX_FUTEX_H

#include <linux/compiler.h>
#include <linux/types.h>

struct inode;
struct mm_struct;
struct task_struct;
union ktime;

/* 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
#define FUTEX_WAIT_BITSET	9
#define FUTEX_WAKE_BITSET	10
#define FUTEX_WAIT_REQUEUE_PI	11
#define FUTEX_CMP_REQUEUE_PI	12

#define FUTEX_PRIVATE_FLAG	128
#define FUTEX_CLOCK_REALTIME	256
#define FUTEX_CMD_MASK		~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)

#define FUTEX_WAIT_PRIVATE	(FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAKE_PRIVATE	(FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
#define FUTEX_REQUEUE_PRIVATE	(FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAKE_OP_PRIVATE	(FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
#define FUTEX_LOCK_PI_PRIVATE	(FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
#define FUTEX_UNLOCK_PI_PRIVATE	(FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAIT_BITSET_PRIVATE	(FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAKE_BITSET_PRIVATE	(FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAIT_REQUEUE_PI_PRIVATE	(FUTEX_WAIT_REQUEUE_PI | \
					 FUTEX_PRIVATE_FLAG)
#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:
 */
#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

/*
 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
 * match of any bit.
 */
#define FUTEX_BITSET_MATCH_ANY	0xffffffff

#ifdef __KERNEL__
long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
	      u32 __user *uaddr2, u32 val2, u32 val3);

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

/*
 * Futexes are matched on equal values of this key.
 * The key type depends on whether it's a shared or private mapping.
 * Don't rearrange members without looking at hash_futex().
 *
 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
 * We use the two low order bits of offset to tell what is the kind of key :
 *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
 *       (no reference on an inode or mm)
 *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
 *	mapped on a file (reference on the underlying inode)
 *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
 *       (but private mapping on an mm, and reference taken on it)
*/

#define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */

union futex_key {
	struct {
		unsigned long pgoff;
		struct inode *inode;
		int offset;
	} shared;
	struct {
		unsigned long address;
		struct mm_struct *mm;
		int offset;
	} private;
	struct {
		unsigned long word;
		void *ptr;
		int offset;
	} both;
};

#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }

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

#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
286100a6 AD	4	#include <linux/compiler.h>
286100a6 AD	5	#include <linux/types.h>
0771dfef	6
286100a6 AD	7	struct inode;
	8	struct mm_struct;
	9	struct task_struct;
c19384b5 PP	10	union ktime;
c19384b5 PP	11
1da177e4 LT	12	/* Second argument to futex syscall */
	13
	14
4732efbe JJ	15	#define FUTEX_WAIT 0
	16	#define FUTEX_WAKE 1
	17	#define FUTEX_FD 2
	18	#define FUTEX_REQUEUE 3
	19	#define FUTEX_CMP_REQUEUE 4
	20	#define FUTEX_WAKE_OP 5
c87e2837 IM	21	#define FUTEX_LOCK_PI 6
	22	#define FUTEX_UNLOCK_PI 7
	23	#define FUTEX_TRYLOCK_PI 8
cd689985 TG	24	#define FUTEX_WAIT_BITSET 9
cd689985 TG	25	#define FUTEX_WAKE_BITSET 10
52400ba9	26	#define FUTEX_WAIT_REQUEUE_PI 11
ba9c22f2	27	#define FUTEX_CMP_REQUEUE_PI 12
1da177e4	28
34f01cc1	29	#define FUTEX_PRIVATE_FLAG 128
1acdac10 TG	30	#define FUTEX_CLOCK_REALTIME 256
1acdac10 TG	31	#define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG \| FUTEX_CLOCK_REALTIME)
34f01cc1 ED	32
	33	#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT \| FUTEX_PRIVATE_FLAG)
	34	#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE \| FUTEX_PRIVATE_FLAG)
	35	#define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE \| FUTEX_PRIVATE_FLAG)
	36	#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE \| FUTEX_PRIVATE_FLAG)
	37	#define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP \| FUTEX_PRIVATE_FLAG)
	38	#define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI \| FUTEX_PRIVATE_FLAG)
	39	#define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI \| FUTEX_PRIVATE_FLAG)
	40	#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI \| FUTEX_PRIVATE_FLAG)
cd689985 TG	41	#define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS \| FUTEX_PRIVATE_FLAG)
cd689985 TG	42	#define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS \| FUTEX_PRIVATE_FLAG)
52400ba9 DH	43	#define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI \| \
52400ba9 DH	44	FUTEX_PRIVATE_FLAG)
52400ba9 DH	45	#define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI \| \
52400ba9 DH	46	FUTEX_PRIVATE_FLAG)
34f01cc1	47
0771dfef IM	48	/*
	49	* Support for robust futexes: the kernel cleans up held futexes at
	50	* thread exit time.
	51	*/
	52
	53	/*
	54	* Per-lock list entry - embedded in user-space locks, somewhere close
	55	* to the futex field. (Note: user-space uses a double-linked list to
	56	* achieve O(1) list add and remove, but the kernel only needs to know
	57	* about the forward link)
	58	*
	59	* NOTE: this structure is part of the syscall ABI, and must not be
	60	* changed.
	61	*/
	62	struct robust_list {
	63	struct robust_list __user *next;
	64	};
	65
	66	/*
	67	* Per-thread list head:
	68	*
	69	* NOTE: this structure is part of the syscall ABI, and must only be
	70	* changed if the change is first communicated with the glibc folks.
	71	* (When an incompatible change is done, we'll increase the structure
	72	* size, which glibc will detect)
	73	*/
	74	struct robust_list_head {
	75	/*
	76	* The head of the list. Points back to itself if empty:
	77	*/
	78	struct robust_list list;
	79
	80	/*
	81	* This relative offset is set by user-space, it gives the kernel
	82	* the relative position of the futex field to examine. This way
	83	* we keep userspace flexible, to freely shape its data-structure,
	84	* without hardcoding any particular offset into the kernel:
	85	*/
	86	long futex_offset;
	87
	88	/*
	89	* The death of the thread may race with userspace setting
	90	* up a lock's links. So to handle this race, userspace first
	91	* sets this field to the address of the to-be-taken lock,
	92	* then does the lock acquire, and then adds itself to the
	93	* list, and then clears this field. Hence the kernel will
	94	* always have full knowledge of all locks that the thread
	95	* _might_ have taken. We check the owner TID in any case,
	96	* so only truly owned locks will be handled.
	97	*/
	98	struct robust_list __user *list_op_pending;
	99	};
	100
	101	/*
	102	* Are there any waiters for this robust futex:
	103	*/
	104	#define FUTEX_WAITERS 0x80000000
	105
	106	/*
	107	* The kernel signals via this bit that a thread holding a futex
	108	* has exited without unlocking the futex. The kernel also does
	109	* a FUTEX_WAKE on such futexes, after setting the bit, to wake
	110	* up any possible waiters:
	111	*/
112	#define FUTEX_OWNER_DIED 0x40000000
113
0771dfef IM	114	/*
	115	* The rest of the robust-futex field is for the TID:
	116	*/
bd197234	117	#define FUTEX_TID_MASK 0x3fffffff
0771dfef IM	118
0771dfef IM	119	/*
76b81e2b IM	120	* This limit protects against a deliberately circular list.
76b81e2b IM	121	* (Not worth introducing an rlimit for it)
0771dfef	122	*/
76b81e2b	123	#define ROBUST_LIST_LIMIT 2048
0771dfef	124
cd689985 TG	125	/*
	126	* bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
	127	* match of any bit.
	128	*/
	129	#define FUTEX_BITSET_MATCH_ANY 0xffffffff
	130
58f64d83	131	#ifdef __KERNEL__
c19384b5	132	long do_futex(u32 __user uaddr, int op, u32 val, union ktime timeout,
e2970f2f	133	u32 __user *uaddr2, u32 val2, u32 val3);
1da177e4	134
e3f2ddea IM	135	extern int
e3f2ddea IM	136	handle_futex_death(u32 __user uaddr, struct task_struct curr, int pi);
0771dfef	137
9adef58b RR	138	/*
	139	* Futexes are matched on equal values of this key.
	140	* The key type depends on whether it's a shared or private mapping.
	141	* Don't rearrange members without looking at hash_futex().
	142	*
	143	* offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
34f01cc1 ED	144	* We use the two low order bits of offset to tell what is the kind of key :
	145	* 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
	146	* (no reference on an inode or mm)
	147	* 01 : Shared futex (PTHREAD_PROCESS_SHARED)
	148	* mapped on a file (reference on the underlying inode)
	149	* 10 : Shared futex (PTHREAD_PROCESS_SHARED)
	150	* (but private mapping on an mm, and reference taken on it)
	151	*/
	152
	153	#define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
	154	#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
	155
9adef58b RR	156	union futex_key {
	157	struct {
	158	unsigned long pgoff;
	159	struct inode *inode;
	160	int offset;
	161	} shared;
	162	struct {
	163	unsigned long address;
	164	struct mm_struct *mm;
	165	int offset;
	166	} private;
	167	struct {
	168	unsigned long word;
	169	void *ptr;
	170	int offset;
	171	} both;
	172	};
9adef58b	173
38d47c1b PZ	174	#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
38d47c1b PZ	175
0771dfef IM	176	#ifdef CONFIG_FUTEX
0771dfef IM	177	extern void exit_robust_list(struct task_struct *curr);
c87e2837	178	extern void exit_pi_state_list(struct task_struct *curr);
a0c1e907	179	extern int futex_cmpxchg_enabled;
0771dfef IM	180	#else
	181	static inline void exit_robust_list(struct task_struct *curr)
	182	{
	183	}
c87e2837 IM	184	static inline void exit_pi_state_list(struct task_struct *curr)
	185	{
	186	}
0771dfef	187	#endif
58f64d83	188	#endif /* __KERNEL__ */
0771dfef	189
4732efbe JJ	190	#define FUTEX_OP_SET 0 /* (int )UADDR2 = OPARG; */
	191	#define FUTEX_OP_ADD 1 /* (int )UADDR2 += OPARG; */
	192	#define FUTEX_OP_OR 2 /* (int )UADDR2 \|= OPARG; */
	193	#define FUTEX_OP_ANDN 3 /* (int )UADDR2 &= ~OPARG; */
	194	#define FUTEX_OP_XOR 4 /* (int )UADDR2 ^= OPARG; */
	195
	196	#define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
	197
	198	#define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
	199	#define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
	200	#define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
	201	#define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
	202	#define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
	203	#define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
	204
	205	/* FUTEX_WAKE_OP will perform atomically
	206	int oldval = (int )UADDR2;
	207	(int )UADDR2 = oldval OP OPARG;
	208	if (oldval CMP CMPARG)
	209	wake UADDR2; */
	210
	211	#define FUTEX_OP(op, oparg, cmp, cmparg) \
	212	(((op & 0xf) << 28) \| ((cmp & 0xf) << 24) \
	213	\| ((oparg & 0xfff) << 12) \| (cmparg & 0xfff))
	214
1da177e4	215	#endif