267 lines
7.5 KiB
C
267 lines
7.5 KiB
C
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/******************************************************************************
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*
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* Copyright © International Business Machines Corp., 2009
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* DESCRIPTION
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* Glibc independent futex library for testing kernel functionality.
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*
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* AUTHOR
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* Darren Hart <dvhart@linux.intel.com>
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*
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* HISTORY
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* 2009-Nov-6: Initial version by Darren Hart <dvhart@linux.intel.com>
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*
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*****************************************************************************/
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#ifndef _FUTEXTEST_H
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#define _FUTEXTEST_H
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <linux/futex.h>
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typedef volatile u_int32_t futex_t;
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#define FUTEX_INITIALIZER 0
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/* Define the newer op codes if the system header file is not up to date. */
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#ifndef FUTEX_WAIT_BITSET
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#define FUTEX_WAIT_BITSET 9
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#endif
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#ifndef FUTEX_WAKE_BITSET
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#define FUTEX_WAKE_BITSET 10
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#endif
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#ifndef FUTEX_WAIT_REQUEUE_PI
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#define FUTEX_WAIT_REQUEUE_PI 11
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#endif
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#ifndef FUTEX_CMP_REQUEUE_PI
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#define FUTEX_CMP_REQUEUE_PI 12
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#endif
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#ifndef FUTEX_WAIT_REQUEUE_PI_PRIVATE
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#define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \
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FUTEX_PRIVATE_FLAG)
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#endif
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#ifndef FUTEX_REQUEUE_PI_PRIVATE
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#define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \
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FUTEX_PRIVATE_FLAG)
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#endif
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/**
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* futex() - SYS_futex syscall wrapper
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* @uaddr: address of first futex
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* @op: futex op code
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* @val: typically expected value of uaddr, but varies by op
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* @timeout: typically an absolute struct timespec (except where noted
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* otherwise). Overloaded by some ops
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* @uaddr2: address of second futex for some ops\
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* @val3: varies by op
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* @opflags: flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
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*
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* futex() is used by all the following futex op wrappers. It can also be
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* used for misuse and abuse testing. Generally, the specific op wrappers
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* should be used instead. It is a macro instead of an static inline function as
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* some of the types over overloaded (timeout is used for nr_requeue for
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* example).
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*
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* These argument descriptions are the defaults for all
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* like-named arguments in the following wrappers except where noted below.
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*/
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#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
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syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
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/**
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* futex_wait() - block on uaddr with optional timeout
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* @timeout: relative timeout
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*/
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static inline int
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futex_wait(futex_t *uaddr, futex_t val, struct timespec *timeout, int opflags)
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{
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return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
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}
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/**
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* futex_wake() - wake one or more tasks blocked on uaddr
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* @nr_wake: wake up to this many tasks
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*/
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static inline int
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futex_wake(futex_t *uaddr, int nr_wake, int opflags)
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{
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return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags);
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}
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/**
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* futex_wait_bitset() - block on uaddr with bitset
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* @bitset: bitset to be used with futex_wake_bitset
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*/
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static inline int
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futex_wait_bitset(futex_t *uaddr, futex_t val, struct timespec *timeout,
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u_int32_t bitset, int opflags)
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{
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return futex(uaddr, FUTEX_WAIT_BITSET, val, timeout, NULL, bitset,
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opflags);
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}
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/**
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* futex_wake_bitset() - wake one or more tasks blocked on uaddr with bitset
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* @bitset: bitset to compare with that used in futex_wait_bitset
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*/
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static inline int
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futex_wake_bitset(futex_t *uaddr, int nr_wake, u_int32_t bitset, int opflags)
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{
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return futex(uaddr, FUTEX_WAKE_BITSET, nr_wake, NULL, NULL, bitset,
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opflags);
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}
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/**
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* futex_lock_pi() - block on uaddr as a PI mutex
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* @detect: whether (1) or not (0) to perform deadlock detection
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*/
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static inline int
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futex_lock_pi(futex_t *uaddr, struct timespec *timeout, int detect,
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int opflags)
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{
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return futex(uaddr, FUTEX_LOCK_PI, detect, timeout, NULL, 0, opflags);
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}
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/**
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* futex_unlock_pi() - release uaddr as a PI mutex, waking the top waiter
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*/
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static inline int
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futex_unlock_pi(futex_t *uaddr, int opflags)
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{
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return futex(uaddr, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0, opflags);
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}
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/**
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* futex_wake_op() - FIXME: COME UP WITH A GOOD ONE LINE DESCRIPTION
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*/
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static inline int
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futex_wake_op(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_wake2,
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int wake_op, int opflags)
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{
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return futex(uaddr, FUTEX_WAKE_OP, nr_wake, nr_wake2, uaddr2, wake_op,
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opflags);
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}
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/**
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* futex_requeue() - requeue without expected value comparison, deprecated
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* @nr_wake: wake up to this many tasks
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* @nr_requeue: requeue up to this many tasks
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*
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* Due to its inherently racy implementation, futex_requeue() is deprecated in
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* favor of futex_cmp_requeue().
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*/
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static inline int
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futex_requeue(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_requeue,
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int opflags)
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{
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return futex(uaddr, FUTEX_REQUEUE, nr_wake, nr_requeue, uaddr2, 0,
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opflags);
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}
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/**
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* futex_cmp_requeue() - requeue tasks from uaddr to uaddr2
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* @nr_wake: wake up to this many tasks
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* @nr_requeue: requeue up to this many tasks
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*/
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static inline int
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futex_cmp_requeue(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake,
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int nr_requeue, int opflags)
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{
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return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2,
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val, opflags);
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}
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/**
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* futex_wait_requeue_pi() - block on uaddr and prepare to requeue to uaddr2
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* @uaddr: non-PI futex source
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* @uaddr2: PI futex target
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*
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* This is the first half of the requeue_pi mechanism. It shall always be
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* paired with futex_cmp_requeue_pi().
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*/
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static inline int
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futex_wait_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2,
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struct timespec *timeout, int opflags)
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{
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return futex(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0,
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opflags);
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}
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/**
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* futex_cmp_requeue_pi() - requeue tasks from uaddr to uaddr2 (PI aware)
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* @uaddr: non-PI futex source
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* @uaddr2: PI futex target
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* @nr_wake: wake up to this many tasks
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* @nr_requeue: requeue up to this many tasks
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*/
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static inline int
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futex_cmp_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake,
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int nr_requeue, int opflags)
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{
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return futex(uaddr, FUTEX_CMP_REQUEUE_PI, nr_wake, nr_requeue, uaddr2,
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val, opflags);
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}
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/**
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* futex_cmpxchg() - atomic compare and exchange
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* @uaddr: The address of the futex to be modified
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* @oldval: The expected value of the futex
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* @newval: The new value to try and assign the futex
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*
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* Implement cmpxchg using gcc atomic builtins.
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* http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
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*
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* Return the old futex value.
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*/
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static inline u_int32_t
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futex_cmpxchg(futex_t *uaddr, u_int32_t oldval, u_int32_t newval)
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{
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return __sync_val_compare_and_swap(uaddr, oldval, newval);
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}
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/**
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* futex_dec() - atomic decrement of the futex value
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* @uaddr: The address of the futex to be modified
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*
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* Return the new futex value.
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*/
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static inline u_int32_t
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futex_dec(futex_t *uaddr)
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{
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return __sync_sub_and_fetch(uaddr, 1);
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}
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/**
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* futex_inc() - atomic increment of the futex value
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* @uaddr: the address of the futex to be modified
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*
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* Return the new futex value.
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*/
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static inline u_int32_t
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futex_inc(futex_t *uaddr)
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{
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return __sync_add_and_fetch(uaddr, 1);
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}
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/**
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* futex_set() - atomic decrement of the futex value
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* @uaddr: the address of the futex to be modified
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* @newval: New value for the atomic_t
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*
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* Return the new futex value.
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*/
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static inline u_int32_t
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futex_set(futex_t *uaddr, u_int32_t newval)
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{
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*uaddr = newval;
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return newval;
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}
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#endif
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