1 | /* $Id: semspinmutex-r0drv-generic.c 100191 2023-06-16 08:04:11Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Spinning Mutex Semaphores, Ring-0 Driver, Generic.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2009-2023 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * The contents of this file may alternatively be used under the terms
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26 | * of the Common Development and Distribution License Version 1.0
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27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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28 | * in the VirtualBox distribution, in which case the provisions of the
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29 | * CDDL are applicable instead of those of the GPL.
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30 | *
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31 | * You may elect to license modified versions of this file under the
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32 | * terms and conditions of either the GPL or the CDDL or both.
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33 | *
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34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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35 | */
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36 |
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37 |
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38 | /*********************************************************************************************************************************
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39 | * Header Files *
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40 | *********************************************************************************************************************************/
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41 | #ifdef RT_OS_WINDOWS
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42 | # include "../nt/the-nt-kernel.h"
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43 | #endif
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44 | #include "internal/iprt.h"
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45 |
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46 | #include <iprt/semaphore.h>
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47 | #include <iprt/asm.h>
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48 | #if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
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49 | # include <iprt/asm-amd64-x86.h>
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50 | #elif defined(RT_ARCH_ARM64) || defined(RT_ARCH_ARM32)
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51 | # include <iprt/asm-arm.h>
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52 | #endif
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53 | #include <iprt/assert.h>
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54 | #include <iprt/err.h>
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55 | #include <iprt/mem.h>
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56 | #include <iprt/thread.h>
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57 | #include "internal/magics.h"
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58 |
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59 |
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60 | /*********************************************************************************************************************************
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61 | * Structures and Typedefs *
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62 | *********************************************************************************************************************************/
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63 | /**
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64 | * Saved state information.
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65 | */
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66 | typedef struct RTSEMSPINMUTEXSTATE
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67 | {
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68 | /** Saved flags register. */
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69 | RTCCUINTREG fSavedFlags;
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70 | /** Preemption state. */
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71 | RTTHREADPREEMPTSTATE PreemptState;
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72 | /** Whether to spin or sleep. */
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73 | bool fSpin;
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74 | /** Whether the flags have been saved. */
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75 | bool fValidFlags;
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76 | } RTSEMSPINMUTEXSTATE;
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77 |
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78 | /**
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79 | * Spinning mutex semaphore.
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80 | */
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81 | typedef struct RTSEMSPINMUTEXINTERNAL
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82 | {
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83 | /** Magic value (RTSEMSPINMUTEX_MAGIC)
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84 | * RTCRITSECT_MAGIC is the value of an initialized & operational section. */
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85 | uint32_t volatile u32Magic;
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86 | /** Flags. This is a combination of RTSEMSPINMUTEX_FLAGS_XXX and
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87 | * RTSEMSPINMUTEX_INT_FLAGS_XXX. */
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88 | uint32_t volatile fFlags;
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89 | /** The owner thread.
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90 | * This is NIL if the semaphore is not owned by anyone. */
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91 | RTNATIVETHREAD volatile hOwner;
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92 | /** Number of threads that are fighting for the lock. */
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93 | int32_t volatile cLockers;
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94 | /** The semaphore to block on. */
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95 | RTSEMEVENT hEventSem;
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96 | /** Saved state information of the owner.
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97 | * This will be restored by RTSemSpinRelease. */
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98 | RTSEMSPINMUTEXSTATE SavedState;
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99 | } RTSEMSPINMUTEXINTERNAL;
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100 |
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101 |
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102 | /*********************************************************************************************************************************
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103 | * Defined Constants And Macros *
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104 | *********************************************************************************************************************************/
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105 | /*#define RTSEMSPINMUTEX_INT_FLAGS_MUST*/
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106 |
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107 | /** Validates the handle, returning if invalid. */
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108 | #define RTSEMSPINMUTEX_VALIDATE_RETURN(pThis) \
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109 | do \
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110 | { \
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111 | uint32_t u32Magic; \
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112 | AssertPtr(pThis); \
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113 | u32Magic = (pThis)->u32Magic; \
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114 | if (u32Magic != RTSEMSPINMUTEX_MAGIC) \
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115 | { \
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116 | AssertMsgFailed(("u32Magic=%#x pThis=%p\n", u32Magic, pThis)); \
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117 | return u32Magic == RTSEMSPINMUTEX_MAGIC_DEAD ? VERR_SEM_DESTROYED : VERR_INVALID_HANDLE; \
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118 | } \
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119 | } while (0)
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120 |
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121 |
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122 | RTDECL(int) RTSemSpinMutexCreate(PRTSEMSPINMUTEX phSpinMtx, uint32_t fFlags)
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123 | {
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124 | RTSEMSPINMUTEXINTERNAL *pThis;
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125 | int rc;
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126 |
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127 | AssertReturn(!(fFlags & ~RTSEMSPINMUTEX_FLAGS_VALID_MASK), VERR_INVALID_PARAMETER);
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128 | AssertPtr(phSpinMtx);
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129 |
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130 | /*
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131 | * Allocate and initialize the structure.
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132 | */
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133 | pThis = (RTSEMSPINMUTEXINTERNAL *)RTMemAllocZ(sizeof(*pThis));
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134 | if (!pThis)
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135 | return VERR_NO_MEMORY;
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136 | pThis->u32Magic = RTSEMSPINMUTEX_MAGIC;
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137 | pThis->fFlags = fFlags;
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138 | pThis->hOwner = NIL_RTNATIVETHREAD;
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139 | pThis->cLockers = 0;
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140 | rc = RTSemEventCreateEx(&pThis->hEventSem, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
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141 | if (RT_SUCCESS(rc))
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142 | {
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143 | *phSpinMtx = pThis;
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144 | return VINF_SUCCESS;
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145 | }
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146 |
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147 | RTMemFree(pThis);
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148 | return rc;
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149 | }
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150 | RT_EXPORT_SYMBOL(RTSemSpinMutexCreate);
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151 |
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152 |
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153 | /**
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154 | * Helper for RTSemSpinMutexTryRequest and RTSemSpinMutexRequest.
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155 | *
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156 | * This will check the current context and see if it's usui
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157 | *
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158 | * @returns VINF_SUCCESS or VERR_SEM_BAD_CONTEXT.
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159 | * @param pState Output structure.
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160 | */
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161 | static int rtSemSpinMutexEnter(RTSEMSPINMUTEXSTATE *pState, RTSEMSPINMUTEXINTERNAL *pThis)
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162 | {
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163 | #ifndef RT_OS_WINDOWS
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164 | RTTHREADPREEMPTSTATE const StateInit = RTTHREADPREEMPTSTATE_INITIALIZER;
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165 | #endif
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166 | int rc = VINF_SUCCESS;
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167 |
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168 | /** @todo Later #1: When entering in interrupt context and we're not able to
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169 | * wake up threads from it, we could try switch the lock into pure
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170 | * spinlock mode. This would require that there are no other threads
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171 | * currently waiting on it and that the RTSEMSPINMUTEX_FLAGS_IRQ_SAFE
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172 | * flag is set.
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173 | *
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174 | * Later #2: Similarly, it is possible to turn on the
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175 | * RTSEMSPINMUTEX_FLAGS_IRQ_SAFE at run time if we manage to grab the
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176 | * semaphore ownership at interrupt time. We might want to try delay the
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177 | * RTSEMSPINMUTEX_FLAGS_IRQ_SAFE even, since we're fine if we get it...
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178 | */
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179 |
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180 | #ifdef RT_OS_WINDOWS
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181 | /*
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182 | * NT: IRQL <= DISPATCH_LEVEL for waking up threads; IRQL < DISPATCH_LEVEL for sleeping.
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183 | */
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184 | pState->PreemptState.uchOldIrql = KeGetCurrentIrql();
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185 | if (pState->PreemptState.uchOldIrql > DISPATCH_LEVEL)
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186 | return VERR_SEM_BAD_CONTEXT;
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187 |
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188 | if (pState->PreemptState.uchOldIrql >= DISPATCH_LEVEL)
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189 | pState->fSpin = true;
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190 | else
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191 | {
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192 | pState->fSpin = false;
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193 | KeRaiseIrql(DISPATCH_LEVEL, &pState->PreemptState.uchOldIrql);
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194 | Assert(pState->PreemptState.uchOldIrql < DISPATCH_LEVEL);
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195 | }
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196 |
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197 | #elif defined(RT_OS_SOLARIS)
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198 | /*
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199 | * Solaris: RTSemEventSignal will do bad stuff on S10 if interrupts are disabled.
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200 | */
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201 | if (!ASMIntAreEnabled())
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202 | return VERR_SEM_BAD_CONTEXT;
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203 |
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204 | pState->fSpin = !RTThreadPreemptIsEnabled(NIL_RTTHREAD);
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205 | if (RTThreadIsInInterrupt(NIL_RTTHREAD))
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206 | {
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207 | if (!(pThis->fFlags & RTSEMSPINMUTEX_FLAGS_IRQ_SAFE))
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208 | rc = VINF_SEM_BAD_CONTEXT; /* Try, but owner might be interrupted. */
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209 | pState->fSpin = true;
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210 | }
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211 | pState->PreemptState = StateInit;
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212 | RTThreadPreemptDisable(&pState->PreemptState);
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213 |
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214 | #elif defined(RT_OS_LINUX) || defined(RT_OS_OS2)
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215 | /*
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216 | * OSes on which RTSemEventSignal can be called from any context.
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217 | */
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218 | pState->fSpin = !RTThreadPreemptIsEnabled(NIL_RTTHREAD);
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219 | if (RTThreadIsInInterrupt(NIL_RTTHREAD))
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220 | {
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221 | if (!(pThis->fFlags & RTSEMSPINMUTEX_FLAGS_IRQ_SAFE))
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222 | rc = VINF_SEM_BAD_CONTEXT; /* Try, but owner might be interrupted. */
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223 | pState->fSpin = true;
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224 | }
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225 | pState->PreemptState = StateInit;
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226 | RTThreadPreemptDisable(&pState->PreemptState);
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227 |
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228 | #else /* PORTME: Check for context where we cannot wake up threads. */
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229 | /*
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230 | * Default: ASSUME thread can be woken up if interrupts are enabled and
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231 | * we're not in an interrupt context.
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232 | * ASSUME that we can go to sleep if preemption is enabled.
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233 | */
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234 | if ( RTThreadIsInInterrupt(NIL_RTTHREAD)
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235 | || !ASMIntAreEnabled())
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236 | return VERR_SEM_BAD_CONTEXT;
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237 |
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238 | pState->fSpin = !RTThreadPreemptIsEnabled(NIL_RTTHREAD);
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239 | pState->PreemptState = StateInit;
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240 | RTThreadPreemptDisable(&pState->PreemptState);
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241 | #endif
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242 |
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243 | /*
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244 | * Disable interrupts if necessary.
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245 | */
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246 | pState->fValidFlags = !!(pThis->fFlags & RTSEMSPINMUTEX_FLAGS_IRQ_SAFE);
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247 | if (pState->fValidFlags)
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248 | pState->fSavedFlags = ASMIntDisableFlags();
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249 | else
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250 | pState->fSavedFlags = 0;
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251 |
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252 | return rc;
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253 | }
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254 |
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255 |
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256 | /**
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257 | * Helper for RTSemSpinMutexTryRequest, RTSemSpinMutexRequest and
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258 | * RTSemSpinMutexRelease.
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259 | *
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260 | * @param pState
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261 | */
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262 | DECL_FORCE_INLINE(void) rtSemSpinMutexLeave(RTSEMSPINMUTEXSTATE *pState)
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263 | {
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264 | /*
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265 | * Restore the interrupt flag.
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266 | */
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267 | if (pState->fValidFlags)
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268 | ASMSetFlags(pState->fSavedFlags);
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269 |
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270 | #ifdef RT_OS_WINDOWS
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271 | /*
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272 | * NT: Lower the IRQL if we raised it.
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273 | */
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274 | if (pState->PreemptState.uchOldIrql < DISPATCH_LEVEL)
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275 | KeLowerIrql(pState->PreemptState.uchOldIrql);
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276 | #else
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277 | /*
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278 | * Default: Restore preemption.
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279 | */
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280 | RTThreadPreemptRestore(&pState->PreemptState);
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281 | #endif
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282 | }
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283 |
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284 |
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285 | RTDECL(int) RTSemSpinMutexTryRequest(RTSEMSPINMUTEX hSpinMtx)
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286 | {
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287 | RTSEMSPINMUTEXINTERNAL *pThis = hSpinMtx;
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288 | RTNATIVETHREAD hSelf = RTThreadNativeSelf();
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289 | RTSEMSPINMUTEXSTATE State;
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290 | bool fRc;
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291 | int rc;
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292 |
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293 | Assert(hSelf != NIL_RTNATIVETHREAD);
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294 | RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
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295 |
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296 | /*
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297 | * Check context, disable preemption and save flags if necessary.
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298 | */
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299 | rc = rtSemSpinMutexEnter(&State, pThis);
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300 | if (RT_FAILURE(rc))
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301 | return rc;
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302 |
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303 | /*
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304 | * Try take the ownership.
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305 | */
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306 | ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
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307 | if (!fRc)
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308 | {
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309 | /* Busy, too bad. Check for attempts at nested access. */
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310 | rc = VERR_SEM_BUSY;
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311 | if (RT_UNLIKELY(pThis->hOwner == hSelf))
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312 | {
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313 | AssertMsgFailed(("%p attempt at nested access\n"));
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314 | rc = VERR_SEM_NESTED;
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315 | }
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316 |
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317 | rtSemSpinMutexLeave(&State);
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318 | return rc;
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319 | }
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320 |
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321 | /*
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322 | * We're the semaphore owner.
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323 | */
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324 | ASMAtomicIncS32(&pThis->cLockers);
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325 | pThis->SavedState = State;
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326 | return VINF_SUCCESS;
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327 | }
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328 | RT_EXPORT_SYMBOL(RTSemSpinMutexTryRequest);
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329 |
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330 |
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331 | RTDECL(int) RTSemSpinMutexRequest(RTSEMSPINMUTEX hSpinMtx)
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332 | {
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333 | RTSEMSPINMUTEXINTERNAL *pThis = hSpinMtx;
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334 | RTNATIVETHREAD hSelf = RTThreadNativeSelf();
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335 | RTSEMSPINMUTEXSTATE State;
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336 | bool fRc;
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337 | int rc;
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338 |
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339 | Assert(hSelf != NIL_RTNATIVETHREAD);
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340 | RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
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341 |
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342 | /*
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343 | * Check context, disable preemption and save flags if necessary.
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344 | */
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345 | rc = rtSemSpinMutexEnter(&State, pThis);
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346 | if (RT_FAILURE(rc))
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347 | return rc;
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348 |
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349 | /*
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350 | * Try take the ownership.
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351 | */
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352 | ASMAtomicIncS32(&pThis->cLockers);
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353 | ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
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354 | if (!fRc)
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355 | {
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356 | uint32_t cSpins;
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357 |
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358 | /*
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359 | * It's busy. Check if it's an attempt at nested access.
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360 | */
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361 | if (RT_UNLIKELY(pThis->hOwner == hSelf))
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362 | {
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363 | AssertMsgFailed(("%p attempt at nested access\n"));
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364 | rtSemSpinMutexLeave(&State);
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365 | return VERR_SEM_NESTED;
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366 | }
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367 |
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368 | /*
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369 | * Return if we're in interrupt context and the semaphore isn't
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370 | * configure to be interrupt safe.
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371 | */
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372 | if (rc == VINF_SEM_BAD_CONTEXT)
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373 | {
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374 | rtSemSpinMutexLeave(&State);
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375 | return VERR_SEM_BAD_CONTEXT;
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376 | }
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377 |
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378 | /*
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379 | * Ok, we have to wait.
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380 | */
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381 | if (State.fSpin)
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382 | {
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383 | for (cSpins = 0; ; cSpins++)
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384 | {
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385 | ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
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386 | if (fRc)
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387 | break;
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388 | ASMNopPause();
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389 | if (RT_UNLIKELY(pThis->u32Magic != RTSEMSPINMUTEX_MAGIC))
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390 | {
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391 | rtSemSpinMutexLeave(&State);
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392 | return VERR_SEM_DESTROYED;
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393 | }
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394 |
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395 | /*
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396 | * "Yield" once in a while. This may lower our IRQL/PIL which
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397 | * may preempting us, and it will certainly stop the hammering
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398 | * of hOwner for a little while.
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399 | */
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400 | if ((cSpins & 0x7f) == 0x1f)
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401 | {
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402 | rtSemSpinMutexLeave(&State);
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403 | rtSemSpinMutexEnter(&State, pThis);
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404 | Assert(State.fSpin);
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405 | }
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406 | }
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407 | }
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408 | else
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409 | {
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410 | for (cSpins = 0;; cSpins++)
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411 | {
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412 | ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
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413 | if (fRc)
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414 | break;
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415 | ASMNopPause();
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416 | if (RT_UNLIKELY(pThis->u32Magic != RTSEMSPINMUTEX_MAGIC))
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417 | {
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418 | rtSemSpinMutexLeave(&State);
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419 | return VERR_SEM_DESTROYED;
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420 | }
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421 |
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422 | if ((cSpins & 15) == 15) /* spin a bit before going sleep (again). */
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423 | {
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424 | rtSemSpinMutexLeave(&State);
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425 |
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426 | rc = RTSemEventWait(pThis->hEventSem, RT_INDEFINITE_WAIT);
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427 | ASMCompilerBarrier();
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428 | if (RT_SUCCESS(rc))
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429 | AssertReturn(pThis->u32Magic == RTSEMSPINMUTEX_MAGIC, VERR_SEM_DESTROYED);
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430 | else if (rc == VERR_INTERRUPTED)
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431 | AssertRC(rc); /* shouldn't happen */
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432 | else
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433 | {
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434 | AssertRC(rc);
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435 | return rc;
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436 | }
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437 |
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438 | rc = rtSemSpinMutexEnter(&State, pThis);
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439 | AssertRCReturn(rc, rc);
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440 | Assert(!State.fSpin);
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441 | }
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442 | }
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443 | }
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444 | }
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445 |
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446 | /*
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447 | * We're the semaphore owner.
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448 | */
|
---|
449 | pThis->SavedState = State;
|
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450 | Assert(pThis->hOwner == hSelf);
|
---|
451 | return VINF_SUCCESS;
|
---|
452 | }
|
---|
453 | RT_EXPORT_SYMBOL(RTSemSpinMutexRequest);
|
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454 |
|
---|
455 |
|
---|
456 | RTDECL(int) RTSemSpinMutexRelease(RTSEMSPINMUTEX hSpinMtx)
|
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457 | {
|
---|
458 | RTSEMSPINMUTEXINTERNAL *pThis = hSpinMtx;
|
---|
459 | RTNATIVETHREAD hSelf = RTThreadNativeSelf();
|
---|
460 | uint32_t cLockers;
|
---|
461 | RTSEMSPINMUTEXSTATE State;
|
---|
462 | bool fRc;
|
---|
463 |
|
---|
464 | Assert(hSelf != NIL_RTNATIVETHREAD);
|
---|
465 | RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
|
---|
466 |
|
---|
467 | /*
|
---|
468 | * Get the saved state and try release the semaphore.
|
---|
469 | */
|
---|
470 | State = pThis->SavedState;
|
---|
471 | ASMCompilerBarrier();
|
---|
472 | ASMAtomicCmpXchgHandle(&pThis->hOwner, NIL_RTNATIVETHREAD, hSelf, fRc);
|
---|
473 | AssertMsgReturn(fRc,
|
---|
474 | ("hOwner=%p hSelf=%p cLockers=%d\n", pThis->hOwner, hSelf, pThis->cLockers),
|
---|
475 | VERR_NOT_OWNER);
|
---|
476 |
|
---|
477 | cLockers = ASMAtomicDecS32(&pThis->cLockers);
|
---|
478 | rtSemSpinMutexLeave(&State);
|
---|
479 | if (cLockers > 0)
|
---|
480 | {
|
---|
481 | int rc = RTSemEventSignal(pThis->hEventSem);
|
---|
482 | AssertReleaseMsg(RT_SUCCESS(rc), ("RTSemEventSignal -> %Rrc\n", rc));
|
---|
483 | }
|
---|
484 | return VINF_SUCCESS;
|
---|
485 | }
|
---|
486 | RT_EXPORT_SYMBOL(RTSemSpinMutexRelease);
|
---|
487 |
|
---|
488 |
|
---|
489 | RTDECL(int) RTSemSpinMutexDestroy(RTSEMSPINMUTEX hSpinMtx)
|
---|
490 | {
|
---|
491 | RTSEMSPINMUTEXINTERNAL *pThis;
|
---|
492 | RTSEMEVENT hEventSem;
|
---|
493 | int rc;
|
---|
494 |
|
---|
495 | if (hSpinMtx == NIL_RTSEMSPINMUTEX)
|
---|
496 | return VINF_SUCCESS;
|
---|
497 | pThis = hSpinMtx;
|
---|
498 | RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
|
---|
499 |
|
---|
500 | /* No destruction races allowed! */
|
---|
501 | AssertMsg( pThis->cLockers == 0
|
---|
502 | && pThis->hOwner == NIL_RTNATIVETHREAD,
|
---|
503 | ("pThis=%p cLockers=%d hOwner=%p\n", pThis, pThis->cLockers, pThis->hOwner));
|
---|
504 |
|
---|
505 | /*
|
---|
506 | * Invalidate the structure, free the mutex and free the structure.
|
---|
507 | */
|
---|
508 | ASMAtomicWriteU32(&pThis->u32Magic, RTSEMSPINMUTEX_MAGIC_DEAD);
|
---|
509 | hEventSem = pThis->hEventSem;
|
---|
510 | pThis->hEventSem = NIL_RTSEMEVENT;
|
---|
511 | rc = RTSemEventDestroy(hEventSem); AssertRC(rc);
|
---|
512 |
|
---|
513 | RTMemFree(pThis);
|
---|
514 | return rc;
|
---|
515 | }
|
---|
516 | RT_EXPORT_SYMBOL(RTSemSpinMutexDestroy);
|
---|
517 |
|
---|