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53e1ffbbce
in a separate word from the _count. This does not permit both items to be updated atomically in a portable manner. As a result, sem_post() must always perform a system call to safely clear _has_waiters. This change removes the _has_waiters field and instead uses the high bit of _count as the _has_waiters flag. A new umtx object type (_usem2) and two new umtx operations are added (SEM_WAIT2 and SEM_WAKE2) to implement these semantics. The older operations are still supported under the COMPAT_FREEBSD9/10 options. The POSIX semaphore API in libc has been updated to use the new implementation. Note that the new implementation is not compatible with the previous implementation. However, this only affects static binaries (which cannot be helped by symbol versioning). Binaries using a dynamic libc will continue to work fine. SEM_MAGIC has been bumped so that mismatched binaries will error rather than corrupting a shared semaphore. In addition, a padding field has been added to sem_t so that it remains the same size. Differential Revision: https://reviews.freebsd.org/D961 Reported by: adrian Reviewed by: kib, jilles (earlier version) Sponsored by: Norse
168 lines
4.7 KiB
C
168 lines
4.7 KiB
C
/*-
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* Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#ifndef _SYS_UMTX_H_
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#define _SYS_UMTX_H_
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#include <sys/_umtx.h>
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#define USYNC_PROCESS_SHARED 0x0001 /* Process shared sync objs */
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#define UMUTEX_UNOWNED 0x0
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#define UMUTEX_CONTESTED 0x80000000U
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#define UMUTEX_PRIO_INHERIT 0x0004 /* Priority inherited mutex */
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#define UMUTEX_PRIO_PROTECT 0x0008 /* Priority protect mutex */
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/* urwlock flags */
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#define URWLOCK_PREFER_READER 0x0002
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#define URWLOCK_WRITE_OWNER 0x80000000U
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#define URWLOCK_WRITE_WAITERS 0x40000000U
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#define URWLOCK_READ_WAITERS 0x20000000U
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#define URWLOCK_MAX_READERS 0x1fffffffU
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#define URWLOCK_READER_COUNT(c) ((c) & URWLOCK_MAX_READERS)
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/* _usem flags */
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#define SEM_NAMED 0x0002
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/* _usem2 count field */
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#define USEM_HAS_WAITERS 0x80000000U
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#define USEM_MAX_COUNT 0x7fffffffU
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#define USEM_COUNT(c) ((c) & USEM_MAX_COUNT)
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/* op code for _umtx_op */
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#define UMTX_OP_RESERVED0 0
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#define UMTX_OP_RESERVED1 1
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#define UMTX_OP_WAIT 2
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#define UMTX_OP_WAKE 3
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#define UMTX_OP_MUTEX_TRYLOCK 4
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#define UMTX_OP_MUTEX_LOCK 5
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#define UMTX_OP_MUTEX_UNLOCK 6
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#define UMTX_OP_SET_CEILING 7
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#define UMTX_OP_CV_WAIT 8
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#define UMTX_OP_CV_SIGNAL 9
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#define UMTX_OP_CV_BROADCAST 10
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#define UMTX_OP_WAIT_UINT 11
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#define UMTX_OP_RW_RDLOCK 12
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#define UMTX_OP_RW_WRLOCK 13
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#define UMTX_OP_RW_UNLOCK 14
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#define UMTX_OP_WAIT_UINT_PRIVATE 15
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#define UMTX_OP_WAKE_PRIVATE 16
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#define UMTX_OP_MUTEX_WAIT 17
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#define UMTX_OP_MUTEX_WAKE 18 /* deprecated */
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#define UMTX_OP_SEM_WAIT 19 /* deprecated */
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#define UMTX_OP_SEM_WAKE 20 /* deprecated */
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#define UMTX_OP_NWAKE_PRIVATE 21
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#define UMTX_OP_MUTEX_WAKE2 22
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#define UMTX_OP_SEM2_WAIT 23
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#define UMTX_OP_SEM2_WAKE 24
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#define UMTX_OP_MAX 25
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/* Flags for UMTX_OP_CV_WAIT */
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#define CVWAIT_CHECK_UNPARKING 0x01
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#define CVWAIT_ABSTIME 0x02
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#define CVWAIT_CLOCKID 0x04
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#define UMTX_ABSTIME 0x01
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#define UMTX_CHECK_UNPARKING CVWAIT_CHECK_UNPARKING
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#ifndef _KERNEL
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int _umtx_op(void *obj, int op, u_long val, void *uaddr, void *uaddr2);
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#else
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/*
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* The umtx_key structure is used by both the Linux futex code and the
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* umtx implementation to map userland addresses to unique keys.
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*/
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enum {
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TYPE_SIMPLE_WAIT,
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TYPE_CV,
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TYPE_SEM,
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TYPE_SIMPLE_LOCK,
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TYPE_NORMAL_UMUTEX,
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TYPE_PI_UMUTEX,
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TYPE_PP_UMUTEX,
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TYPE_RWLOCK,
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TYPE_FUTEX
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};
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/* Key to represent a unique userland synchronous object */
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struct umtx_key {
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int hash;
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int type;
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int shared;
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union {
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struct {
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struct vm_object *object;
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uintptr_t offset;
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} shared;
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struct {
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struct vmspace *vs;
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uintptr_t addr;
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} private;
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struct {
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void *a;
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uintptr_t b;
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} both;
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} info;
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};
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#define THREAD_SHARE 0
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#define PROCESS_SHARE 1
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#define AUTO_SHARE 2
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struct thread;
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static inline int
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umtx_key_match(const struct umtx_key *k1, const struct umtx_key *k2)
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{
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return (k1->type == k2->type &&
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k1->info.both.a == k2->info.both.a &&
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k1->info.both.b == k2->info.both.b);
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}
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int umtx_copyin_timeout(const void *, struct timespec *);
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int umtx_key_get(void *, int, int, struct umtx_key *);
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void umtx_key_release(struct umtx_key *);
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struct umtx_q *umtxq_alloc(void);
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void umtxq_free(struct umtx_q *);
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int kern_umtx_wake(struct thread *, void *, int, int);
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void umtx_pi_adjust(struct thread *, u_char);
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void umtx_thread_init(struct thread *);
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void umtx_thread_fini(struct thread *);
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void umtx_thread_alloc(struct thread *);
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void umtx_thread_exit(struct thread *);
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#endif /* !_KERNEL */
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#endif /* !_SYS_UMTX_H_ */
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