Make sparc use atomic_cas_ulong() for mutex and rwlock operations, and
disable the custom mutex/rwlock code. PR port-sparc/37930. ok martin@
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@ -1,4 +1,4 @@
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# $NetBSD: files.sparc,v 1.144 2008/01/25 21:12:13 joerg Exp $
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# $NetBSD: files.sparc,v 1.145 2008/02/14 14:07:35 ad Exp $
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# @(#)files.sparc 8.1 (Berkeley) 7/19/93
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# sparc-specific configuration info
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@ -298,7 +298,6 @@ file arch/sparc/sparc/kgdb_machdep.c kgdb
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file arch/sparc/sparc/kobj_machdep.c modular
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# sparc/sparc/locore.s is handled specially in the makefile,
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# because it must come first in the "ld" command line.
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file arch/sparc/sparc/lock_stubs.s
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file arch/sparc/sparc/machdep.c
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file arch/sparc/sparc/process_machdep.c
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file arch/sparc/sparc/mem.c
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@ -1,7 +1,7 @@
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/* $NetBSD: mutex.h,v 1.7 2008/01/02 11:48:28 ad Exp $ */
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/* $NetBSD: mutex.h,v 1.8 2008/02/14 14:07:35 ad Exp $ */
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/*-
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* Copyright (c) 2002, 2007 The NetBSD Foundation, Inc.
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* Copyright (c) 2002, 2006 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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@ -39,178 +39,36 @@
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#ifndef _SPARC_MUTEX_H_
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#define _SPARC_MUTEX_H_
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/*
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* There sparc mutex implementation is troublesome, because sparc (v7 and
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* v8) lacks a compare-and-set operation, yet there are many SMP sparc
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* machines in circulation. SMP for spin mutexes is easy - we don't need
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* to know who owns the lock. For adaptive mutexes, we need an aditional
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* interlock.
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*
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* The locked byte set by the sparc 'ldstub' instruction is 0xff. sparc
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* kernels are always loaded above 0xe0000000, and the low 5 bits of any
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* "struct lwp *" are always zero. So, to record the lock owner, we only
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* need 23 bits of space. mtxa_owner contains the mutex owner's address
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* shifted right by 5: the top three bits of which will always be 0xe,
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* overlapping with the interlock at the top byte, which is always 0xff
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* when the mutex is held.
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*
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* For a mutex acquisition, the owner field is set in two steps: first,
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* acquire the interlock (top byte), and second OR in the owner's address.
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* Once the owner field is non zero, it will appear that the mutex is held,
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* by which LWP it does not matter: other LWPs competing for the lock will
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* fall through to mutex_vector_enter(), and either spin or sleep.
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*
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* As a result there is no space for a waiters bit in the owner field. No
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* problem, because it would be hard to synchronise using one without a CAS
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* operation. Note that in order to do unlocked release of adaptive
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* mutexes, we need the effect of MUTEX_SET_WAITERS() to be immediatley
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* visible on the bus. So, adaptive mutexes share the spin lock byte with
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* spin mutexes (set with ldstub), but it is not treated as a lock in its
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* own right, rather as a flag that can be atomically set or cleared.
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*
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* When releasing an adaptive mutex, we first clear the owners field, and
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* then check to see if the waiters byte is set. This ensures that there
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* will always be someone to wake any sleeping waiters up (even it the mutex
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* is acquired immediately after we release it, or if we are preempted
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* immediatley after clearing the owners field). The setting or clearing of
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* the waiters byte is serialized by the turnstile chain lock associated
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* with the mutex.
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*
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* See comments in kern_mutex.c about releasing adaptive mutexes without
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* an interlocking step.
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*/
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#ifndef __MUTEX_PRIVATE
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struct kmutex {
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uintptr_t mtx_pad1;
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uint32_t mtx_pad2;
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};
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#else /* __MUTEX_PRIVATE */
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#include <machine/lock.h>
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struct kmutex {
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union {
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/* Adaptive mutex */
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volatile uintptr_t mtxu_owner; /* 0-3 */
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__cpu_simple_lock_t mtxu_interlock; /* 0 */
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/* Spin mutex. */
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volatile uintptr_t mtxa_owner;
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#ifdef __MUTEX_PRIVATE
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struct {
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uint8_t mtxs_dummy; /* 0 */
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uint8_t mtxs_unused1; /* 1 */
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ipl_cookie_t mtxs_ipl; /* 2 */
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uint8_t mtxs_unused2; /* 3 */
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volatile uint8_t mtxs_dummy;
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ipl_cookie_t mtxs_ipl;
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__cpu_simple_lock_t mtxs_lock;
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volatile uint8_t mtxs_unused;
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} s;
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#endif
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} u;
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__cpu_simple_lock_t mtx_lock; /* 4 */
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uint8_t mtx_dodebug; /* 5 */
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uint8_t mtx_isspin; /* 6 */
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uint8_t mtx_pad[1]; /* 7 */
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};
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#define __HAVE_MUTEX_STUBS 1
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#if 0 /* does not work for MP yet */
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#define __HAVE_SPIN_MUTEX_STUBS 1
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#endif
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#ifdef __MUTEX_PRIVATE
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#define mtx_owner u.mtxu_owner
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#define mtx_interlock u.mtxu_interlock
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#define mtx_dummy u.s.mtxs_dummy
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#define mtx_ipl u.s.mtxs_ipl
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#define mtx_owner u.mtxa_owner
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#define mtx_ipl u.s.mtxs_ipl
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#define mtx_lock u.s.mtxs_lock
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static inline uintptr_t
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MUTEX_OWNER(uintptr_t owner)
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{
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return owner << 5;
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}
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#define __HAVE_SIMPLE_MUTEXES 1
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static inline int
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MUTEX_OWNED(uintptr_t owner)
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{
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return owner != 0;
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}
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#define MUTEX_RECEIVE(mtx) /* nothing */
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#define MUTEX_GIVE(mtx) /* nothing */
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static inline int
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MUTEX_SET_WAITERS(kmutex_t *mtx, uintptr_t owner)
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{
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(void)__cpu_simple_lock_try(&mtx->mtx_lock);
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return mtx->mtx_owner != 0;
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}
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#define MUTEX_CAS(p, o, n) \
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(_atomic_cas_ulong((volatile unsigned long *)(p), (o), (n)) == (o))
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static inline int
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MUTEX_HAS_WAITERS(volatile kmutex_t *mtx)
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{
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if (mtx->mtx_owner == 0)
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return 0;
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return mtx->mtx_lock == __SIMPLELOCK_LOCKED;
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}
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static inline void
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MUTEX_INITIALIZE_SPIN(kmutex_t *mtx, bool dodebug, int ipl)
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{
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mtx->mtx_dodebug = dodebug;
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mtx->mtx_isspin = 1;
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mtx->mtx_ipl = makeiplcookie(ipl);
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mtx->mtx_interlock = __SIMPLELOCK_LOCKED;
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__cpu_simple_lock_init(&mtx->mtx_lock);
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}
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static inline void
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MUTEX_INITIALIZE_ADAPTIVE(kmutex_t *mtx, bool dodebug)
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{
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mtx->mtx_dodebug = dodebug;
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mtx->mtx_isspin = 0;
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__cpu_simple_lock_init(&mtx->mtx_lock);
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}
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static inline void
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MUTEX_DESTROY(kmutex_t *mtx)
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{
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mtx->mtx_owner = (uintptr_t)-1L;
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}
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static inline bool
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MUTEX_DEBUG_P(kmutex_t *mtx)
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{
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return mtx->mtx_dodebug != 0;
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}
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static inline int
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MUTEX_SPIN_P(volatile kmutex_t *mtx)
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{
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return mtx->mtx_isspin != 0;
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}
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static inline int
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MUTEX_ADAPTIVE_P(volatile kmutex_t *mtx)
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{
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return mtx->mtx_isspin == 0;
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}
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static inline int
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MUTEX_ACQUIRE(kmutex_t *mtx, uintptr_t curthread)
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{
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if (!__cpu_simple_lock_try(&mtx->mtx_interlock))
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return 0;
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mtx->mtx_owner = (curthread >> 5) | 0xf8000000;
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return 1;
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}
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static inline void
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MUTEX_RELEASE(kmutex_t *mtx)
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{
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mtx->mtx_owner = 0;
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__cpu_simple_unlock(&mtx->mtx_lock);
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}
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static inline void
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MUTEX_CLEAR_WAITERS(kmutex_t *mtx)
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{
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__cpu_simple_unlock(&mtx->mtx_lock);
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}
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unsigned long _atomic_cas_ulong(volatile unsigned long *,
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unsigned long, unsigned long);
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#endif /* __MUTEX_PRIVATE */
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@ -1,7 +1,7 @@
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/* $NetBSD: rwlock.h,v 1.3 2007/11/21 10:19:08 yamt Exp $ */
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/* $NetBSD: rwlock.h,v 1.4 2008/02/14 14:07:35 ad Exp $ */
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/*-
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* Copyright (c) 2002, 2007 The NetBSD Foundation, Inc.
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* Copyright (c) 2002, 2006 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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@ -50,9 +50,11 @@ struct krwlock {
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#define RW_RECEIVE(rw) /* nothing */
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#define RW_GIVE(rw) /* nothing */
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#define RW_CAS(p, o, n) _lock_cas((p), (o), (n))
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#define RW_CAS(p, o, n) \
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(_atomic_cas_ulong((volatile unsigned long *)(p), (o), (n)) == (o))
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int _lock_cas(volatile uintptr_t *, uintptr_t, uintptr_t);
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unsigned long _atomic_cas_ulong(volatile unsigned long *,
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unsigned long, unsigned long);
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#endif /* __RWLOCK_PRIVATE */
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