[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 <linux/mm_types.h>

#include <uapi/linux/futex.h>

struct inode;
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;
		/* unsigned int node; */
	} shared;
	struct {
		union {
			struct mm_struct *mm;
			u64 __tmp;
		};
		unsigned long address;
		unsigned int offset;
		/* unsigned int node; */
	} private;
	struct {
		u64 ptr;
		unsigned long word;
		unsigned int offset;
		unsigned int node;	/* NOT hashed! */
	} 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);
int futex_hash_prctl(unsigned long arg2, unsigned long arg3, unsigned long arg4);

#ifdef CONFIG_FUTEX_PRIVATE_HASH
int futex_hash_allocate_default(void);
void futex_hash_free(struct mm_struct *mm);

static inline void futex_mm_init(struct mm_struct *mm)
{
	RCU_INIT_POINTER(mm->futex_phash, NULL);
	mm->futex_phash_new = NULL;
	mutex_init(&mm->futex_hash_lock);
}

#else /* !CONFIG_FUTEX_PRIVATE_HASH */
static inline int futex_hash_allocate_default(void) { return 0; }
static inline void futex_hash_free(struct mm_struct *mm) { }
static inline void futex_mm_init(struct mm_struct *mm) { }
#endif /* CONFIG_FUTEX_PRIVATE_HASH */

#else /* !CONFIG_FUTEX */
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;
}
static inline int futex_hash_prctl(unsigned long arg2, unsigned long arg3, unsigned long arg4)
{
	return -EINVAL;
}
static inline int futex_hash_allocate_default(void)
{
	return 0;
}
static inline void futex_hash_free(struct mm_struct *mm) { }
static inline void futex_mm_init(struct mm_struct *mm) { }

#endif

#endif
Commit	Line	Data
	1	/* SPDX-License-Identifier: GPL-2.0 */
	2	#ifndef _LINUX_FUTEX_H
	3	#define _LINUX_FUTEX_H
	4
	5	#include <linux/sched.h>
	6	#include <linux/ktime.h>
	7	#include <linux/mm_types.h>
	8
	9	#include <uapi/linux/futex.h>
	10
	11	struct inode;
	12	struct task_struct;
	13
	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.
	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
	32	union futex_key {
	33	struct {
	34	u64 i_seq;
	35	unsigned long pgoff;
	36	unsigned int offset;
	37	/* unsigned int node; */
	38	} shared;
	39	struct {
	40	union {
	41	struct mm_struct *mm;
	42	u64 __tmp;
	43	};
	44	unsigned long address;
	45	unsigned int offset;
	46	/* unsigned int node; */
	47	} private;
	48	struct {
	49	u64 ptr;
	50	unsigned long word;
	51	unsigned int offset;
	52	unsigned int node; /* NOT hashed! */
	53	} both;
	54	};
	55
	56	#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }
	57
	58	#ifdef CONFIG_FUTEX
	59	enum {
	60	FUTEX_STATE_OK,
	61	FUTEX_STATE_EXITING,
	62	FUTEX_STATE_DEAD,
	63	};
	64
	65	static inline void futex_init_task(struct task_struct *tsk)
	66	{
	67	tsk->robust_list = NULL;
	68	#ifdef CONFIG_COMPAT
	69	tsk->compat_robust_list = NULL;
	70	#endif
	71	INIT_LIST_HEAD(&tsk->pi_state_list);
	72	tsk->pi_state_cache = NULL;
	73	tsk->futex_state = FUTEX_STATE_OK;
	74	mutex_init(&tsk->futex_exit_mutex);
	75	}
	76
	77	void futex_exit_recursive(struct task_struct *tsk);
	78	void futex_exit_release(struct task_struct *tsk);
	79	void futex_exec_release(struct task_struct *tsk);
	80
	81	long do_futex(u32 __user uaddr, int op, u32 val, ktime_t timeout,
	82	u32 __user *uaddr2, u32 val2, u32 val3);
	83	int futex_hash_prctl(unsigned long arg2, unsigned long arg3, unsigned long arg4);
	84
	85	#ifdef CONFIG_FUTEX_PRIVATE_HASH
	86	int futex_hash_allocate_default(void);
	87	void futex_hash_free(struct mm_struct *mm);
	88
	89	static inline void futex_mm_init(struct mm_struct *mm)
	90	{
	91	RCU_INIT_POINTER(mm->futex_phash, NULL);
	92	mm->futex_phash_new = NULL;
	93	mutex_init(&mm->futex_hash_lock);
	94	}
	95
	96	#else /* !CONFIG_FUTEX_PRIVATE_HASH */
	97	static inline int futex_hash_allocate_default(void) { return 0; }
	98	static inline void futex_hash_free(struct mm_struct *mm) { }
	99	static inline void futex_mm_init(struct mm_struct *mm) { }
	100	#endif /* CONFIG_FUTEX_PRIVATE_HASH */
	101
	102	#else /* !CONFIG_FUTEX */
	103	static inline void futex_init_task(struct task_struct *tsk) { }
	104	static inline void futex_exit_recursive(struct task_struct *tsk) { }
	105	static inline void futex_exit_release(struct task_struct *tsk) { }
	106	static inline void futex_exec_release(struct task_struct *tsk) { }
	107	static inline long do_futex(u32 __user *uaddr, int op, u32 val,
	108	ktime_t timeout, u32 __user uaddr2,
	109	u32 val2, u32 val3)
	110	{
	111	return -EINVAL;
	112	}
	113	static inline int futex_hash_prctl(unsigned long arg2, unsigned long arg3, unsigned long arg4)
	114	{
	115	return -EINVAL;
	116	}
	117	static inline int futex_hash_allocate_default(void)
	118	{
	119	return 0;
	120	}
	121	static inline void futex_hash_free(struct mm_struct *mm) { }
	122	static inline void futex_mm_init(struct mm_struct *mm) { }
	123
	124	#endif
	125
	126	#endif