Release 4.12 include/uapi/linux/futex.h

Directory: include/uapi/linux
#ifndef _UAPI_LINUX_FUTEX_H

#define _UAPI_LINUX_FUTEX_H

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

#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_BITSET | FUTEX_PRIVATE_FLAG)

#define FUTEX_WAKE_BITSET_PRIVATE	(FUTEX_WAKE_BITSET | 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



#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 /* _UAPI_LINUX_FUTEX_H */
Overall Contributors
Person Tokens Prop Commits CommitProp
David Howells 263 100.00% 1 100.00%
Total 263 100.00% 1 100.00%
Directory: include/uapi/linux

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Person	Tokens	Prop	Commits	CommitProp
David Howells	263	100.00%	1	100.00%
Total	263	100.00%	1	100.00%
cregit-Linux how code gets into the kernel

Release 4.12 include/uapi/linux/futex.h

Overall Contributors
