futex.h 2.08 KB
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_FUTEX_H
#define _LINUX_FUTEX_H

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#include <linux/ktime.h>
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#include <uapi/linux/futex.h>
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struct inode;
struct mm_struct;
struct task_struct;

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

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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;
};

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

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#ifdef CONFIG_FUTEX
extern void exit_robust_list(struct task_struct *curr);
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long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
	      u32 __user *uaddr2, u32 val2, u32 val3);
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#ifdef CONFIG_HAVE_FUTEX_CMPXCHG
#define futex_cmpxchg_enabled 1
#else
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extern int futex_cmpxchg_enabled;
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#endif
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#else
static inline void exit_robust_list(struct task_struct *curr)
{
}
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static inline long do_futex(u32 __user *uaddr, int op, u32 val,
			    ktime_t *timeout, u32 __user *uaddr2,
			    u32 val2, u32 val3)
{
	return -EINVAL;
}
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#endif

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