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

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FUTEX_H
#define _LINUX_FUTEX_H

#include <linux/sched.h>
#include <linux/ktime.h>

#include <uapi/linux/futex.h>

struct inode;
struct mm_struct;
struct task_struct;

/*
 * 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 {
		u64 i_seq;
		unsigned long pgoff;
		unsigned int offset;
	} shared;
	struct {
		union {
			struct mm_struct *mm;
			u64 __tmp;
		};
		unsigned long address;
		unsigned int offset;
	} private;
	struct {
		u64 ptr;
		unsigned long word;
		unsigned int offset;
	} both;
};

#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }

#ifdef CONFIG_FUTEX
enum {
	FUTEX_STATE_OK,
	FUTEX_STATE_EXITING,
	FUTEX_STATE_DEAD,
};

static inline void futex_init_task(struct task_struct *tsk)
{
	tsk->robust_list = NULL;
#ifdef CONFIG_COMPAT
	tsk->compat_robust_list = NULL;
#endif
	INIT_LIST_HEAD(&tsk->pi_state_list);
	tsk->pi_state_cache = NULL;
	tsk->futex_state = FUTEX_STATE_OK;
	mutex_init(&tsk->futex_exit_mutex);
}

void futex_exit_recursive(struct task_struct *tsk);
void futex_exit_release(struct task_struct *tsk);
void futex_exec_release(struct task_struct *tsk);

long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
	      u32 __user *uaddr2, u32 val2, u32 val3);
#else
static inline void futex_init_task(struct task_struct *tsk) { }
static inline void futex_exit_recursive(struct task_struct *tsk) { }
static inline void futex_exit_release(struct task_struct *tsk) { }
static inline void futex_exec_release(struct task_struct *tsk) { }
static inline long do_futex(u32 __user *uaddr, int op, u32 val,
			    ktime_t *timeout, u32 __user *uaddr2,
			    u32 val2, u32 val3)
{
	return -EINVAL;
}
#endif

#endif
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1da177e4 LT	2	#ifndef _LINUX_FUTEX_H
	3	#define _LINUX_FUTEX_H
	4
ba31c1a4	5	#include <linux/sched.h>
2456e855	6	#include <linux/ktime.h>
ba31c1a4	7
607ca46e	8	#include <uapi/linux/futex.h>
0771dfef	9
9064a678 MF	10	struct inode;
	11	struct mm_struct;
	12	struct task_struct;
9064a678	13
9adef58b RR	14	/*
	15	* Futexes are matched on equal values of this key.
	16	* The key type depends on whether it's a shared or private mapping.
	17	* Don't rearrange members without looking at hash_futex().
	18	*
	19	* offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
34f01cc1 ED	20	* We use the two low order bits of offset to tell what is the kind of key :
	21	* 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
	22	* (no reference on an inode or mm)
	23	* 01 : Shared futex (PTHREAD_PROCESS_SHARED)
	24	* mapped on a file (reference on the underlying inode)
	25	* 10 : Shared futex (PTHREAD_PROCESS_SHARED)
	26	* (but private mapping on an mm, and reference taken on it)
	27	*/
	28
	29	#define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
	30	#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
	31
9adef58b RR	32	union futex_key {
9adef58b RR	33	struct {
8019ad13	34	u64 i_seq;
9adef58b	35	unsigned long pgoff;
8019ad13	36	unsigned int offset;
9adef58b RR	37	} shared;
9adef58b RR	38	struct {
8019ad13 PZ	39	union {
	40	struct mm_struct *mm;
	41	u64 __tmp;
	42	};
9adef58b	43	unsigned long address;
8019ad13	44	unsigned int offset;
9adef58b RR	45	} private;
9adef58b RR	46	struct {
8019ad13	47	u64 ptr;
9adef58b	48	unsigned long word;
8019ad13	49	unsigned int offset;
9adef58b RR	50	} both;
9adef58b RR	51	};
9adef58b	52
8019ad13	53	#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }
38d47c1b	54
0771dfef	55	#ifdef CONFIG_FUTEX
3d4775df TG	56	enum {
3d4775df TG	57	FUTEX_STATE_OK,
18f69438	58	FUTEX_STATE_EXITING,
3d4775df TG	59	FUTEX_STATE_DEAD,
3d4775df TG	60	};
2de0db99	61
ba31c1a4	62	static inline void futex_init_task(struct task_struct *tsk)
0771dfef	63	{
ba31c1a4 TG	64	tsk->robust_list = NULL;
	65	#ifdef CONFIG_COMPAT
	66	tsk->compat_robust_list = NULL;
	67	#endif
	68	INIT_LIST_HEAD(&tsk->pi_state_list);
	69	tsk->pi_state_cache = NULL;
3d4775df	70	tsk->futex_state = FUTEX_STATE_OK;
3f186d97	71	mutex_init(&tsk->futex_exit_mutex);
3d4775df TG	72	}
3d4775df TG	73
18f69438	74	void futex_exit_recursive(struct task_struct *tsk);
150d7158 TG	75	void futex_exit_release(struct task_struct *tsk);
150d7158 TG	76	void futex_exec_release(struct task_struct *tsk);
ba31c1a4 TG	77
	78	long do_futex(u32 __user uaddr, int op, u32 val, ktime_t timeout,
	79	u32 __user *uaddr2, u32 val2, u32 val3);
	80	#else
	81	static inline void futex_init_task(struct task_struct *tsk) { }
18f69438	82	static inline void futex_exit_recursive(struct task_struct *tsk) { }
150d7158 TG	83	static inline void futex_exit_release(struct task_struct *tsk) { }
150d7158 TG	84	static inline void futex_exec_release(struct task_struct *tsk) { }
2de0db99 DB	85	static inline long do_futex(u32 __user *uaddr, int op, u32 val,
	86	ktime_t timeout, u32 __user uaddr2,
	87	u32 val2, u32 val3)
	88	{
	89	return -EINVAL;
	90	}
bc2eecd7 NP	91	#endif
bc2eecd7 NP	92
1da177e4	93	#endif