1 | /* $Id: semmutex-linux.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Mutex Semaphore, Linux (2.6.x+).
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2006-2023 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 | #include <iprt/semaphore.h>
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42 | #include "internal/iprt.h"
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43 |
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44 | #include <iprt/alloc.h>
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45 | #include <iprt/asm.h>
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46 | #include <iprt/assert.h>
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47 | #include <iprt/err.h>
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48 | #include <iprt/lockvalidator.h>
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49 | #include <iprt/thread.h>
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50 | #include <iprt/time.h>
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51 | #include "internal/magics.h"
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52 | #include "internal/strict.h"
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53 |
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54 | #include <errno.h>
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55 | #include <limits.h>
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56 | #include <pthread.h>
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57 | #include <unistd.h>
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58 | #include <sys/time.h>
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59 | #include <sys/syscall.h>
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60 | #if 0 /* With 2.6.17 futex.h has become C++ unfriendly. */
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61 | # include <linux/futex.h>
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62 | #else
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63 | # define FUTEX_WAIT 0
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64 | # define FUTEX_WAKE 1
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65 | #endif
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66 |
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67 |
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68 | /*********************************************************************************************************************************
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69 | * Structures and Typedefs *
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70 | *********************************************************************************************************************************/
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71 | /**
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72 | * Linux internal representation of a Mutex semaphore.
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73 | */
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74 | struct RTSEMMUTEXINTERNAL
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75 | {
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76 | /** The futex state variable.
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77 | * 0 means unlocked.
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78 | * 1 means locked, no waiters.
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79 | * 2 means locked, one or more waiters.
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80 | */
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81 | int32_t volatile iState;
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82 | /** Nesting count. */
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83 | uint32_t volatile cNestings;
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84 | /** The owner of the mutex. */
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85 | pthread_t volatile Owner;
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86 | /** Magic value (RTSEMMUTEX_MAGIC). */
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87 | uint32_t volatile u32Magic;
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88 | #ifdef RTSEMMUTEX_STRICT
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89 | /** Lock validator record associated with this mutex. */
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90 | RTLOCKVALRECEXCL ValidatorRec;
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91 | #endif
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92 | };
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93 |
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94 |
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95 |
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96 | /**
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97 | * Wrapper for the futex syscall.
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98 | */
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99 | static long sys_futex(int32_t volatile *uaddr, int op, int val, struct timespec *utime, int32_t *uaddr2, int val3)
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100 | {
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101 | errno = 0;
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102 | long rc = syscall(__NR_futex, uaddr, op, val, utime, uaddr2, val3);
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103 | if (rc < 0)
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104 | {
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105 | Assert(rc == -1);
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106 | rc = -errno;
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107 | }
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108 | return rc;
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109 | }
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110 |
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111 |
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112 | #undef RTSemMutexCreate
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113 | RTDECL(int) RTSemMutexCreate(PRTSEMMUTEX phMutexSem)
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114 | {
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115 | return RTSemMutexCreateEx(phMutexSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
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116 | }
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117 |
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118 |
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119 | RTDECL(int) RTSemMutexCreateEx(PRTSEMMUTEX phMutexSem, uint32_t fFlags,
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120 | RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...)
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121 | {
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122 | AssertReturn(!(fFlags & ~RTSEMMUTEX_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
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123 |
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124 | /*
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125 | * Allocate semaphore handle.
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126 | */
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127 | struct RTSEMMUTEXINTERNAL *pThis = (struct RTSEMMUTEXINTERNAL *)RTMemAlloc(sizeof(struct RTSEMMUTEXINTERNAL));
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128 | if (pThis)
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129 | {
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130 | pThis->u32Magic = RTSEMMUTEX_MAGIC;
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131 | pThis->iState = 0;
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132 | pThis->Owner = (pthread_t)~0;
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133 | pThis->cNestings = 0;
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134 | #ifdef RTSEMMUTEX_STRICT
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135 | if (!pszNameFmt)
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136 | {
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137 | static uint32_t volatile s_iMutexAnon = 0;
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138 | RTLockValidatorRecExclInit(&pThis->ValidatorRec, hClass, uSubClass, pThis,
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139 | !(fFlags & RTSEMMUTEX_FLAGS_NO_LOCK_VAL),
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140 | "RTSemMutex-%u", ASMAtomicIncU32(&s_iMutexAnon) - 1);
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141 | }
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142 | else
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143 | {
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144 | va_list va;
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145 | va_start(va, pszNameFmt);
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146 | RTLockValidatorRecExclInitV(&pThis->ValidatorRec, hClass, uSubClass, pThis,
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147 | !(fFlags & RTSEMMUTEX_FLAGS_NO_LOCK_VAL), pszNameFmt, va);
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148 | va_end(va);
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149 | }
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150 | #else
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151 | RT_NOREF(hClass, uSubClass, pszNameFmt);
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152 | #endif
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153 |
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154 | *phMutexSem = pThis;
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155 | return VINF_SUCCESS;
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156 | }
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157 |
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158 | return VERR_NO_MEMORY;
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159 | }
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160 |
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161 |
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162 | RTDECL(int) RTSemMutexDestroy(RTSEMMUTEX hMutexSem)
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163 | {
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164 | /*
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165 | * Validate input.
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166 | */
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167 | if (hMutexSem == NIL_RTSEMMUTEX)
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168 | return VINF_SUCCESS;
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169 | struct RTSEMMUTEXINTERNAL *pThis = hMutexSem;
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170 | AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
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171 | AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC,
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172 | ("hMutexSem=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
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173 | VERR_INVALID_HANDLE);
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174 |
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175 | /*
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176 | * Invalidate the semaphore and wake up anyone waiting on it.
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177 | */
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178 | ASMAtomicWriteU32(&pThis->u32Magic, RTSEMMUTEX_MAGIC_DEAD);
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179 | if (ASMAtomicXchgS32(&pThis->iState, 0) > 0)
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180 | {
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181 | sys_futex(&pThis->iState, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
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182 | usleep(1000);
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183 | }
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184 | pThis->Owner = (pthread_t)~0;
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185 | pThis->cNestings = 0;
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186 | #ifdef RTSEMMUTEX_STRICT
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187 | RTLockValidatorRecExclDelete(&pThis->ValidatorRec);
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188 | #endif
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189 |
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190 | /*
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191 | * Free the semaphore memory and be gone.
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192 | */
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193 | RTMemFree(pThis);
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194 | return VINF_SUCCESS;
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195 | }
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196 |
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197 |
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198 | RTDECL(uint32_t) RTSemMutexSetSubClass(RTSEMMUTEX hMutexSem, uint32_t uSubClass)
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199 | {
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200 | #ifdef RTSEMMUTEX_STRICT
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201 | /*
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202 | * Validate.
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203 | */
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204 | RTSEMMUTEXINTERNAL *pThis = hMutexSem;
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205 | AssertPtrReturn(pThis, RTLOCKVAL_SUB_CLASS_INVALID);
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206 | AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID);
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207 |
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208 | return RTLockValidatorRecExclSetSubClass(&pThis->ValidatorRec, uSubClass);
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209 | #else
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210 | RT_NOREF(hMutexSem, uSubClass);
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211 | return RTLOCKVAL_SUB_CLASS_INVALID;
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212 | #endif
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213 | }
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214 |
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215 |
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216 | DECL_FORCE_INLINE(int) rtSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, bool fAutoResume, PCRTLOCKVALSRCPOS pSrcPos)
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217 | {
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218 | RT_NOREF(pSrcPos);
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219 |
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220 | /*
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221 | * Validate input.
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222 | */
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223 | struct RTSEMMUTEXINTERNAL *pThis = hMutexSem;
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224 | AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
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225 | AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
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226 |
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227 | /*
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228 | * Check if nested request.
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229 | */
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230 | pthread_t Self = pthread_self();
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231 | if ( pThis->Owner == Self
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232 | && pThis->cNestings > 0)
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233 | {
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234 | #ifdef RTSEMMUTEX_STRICT
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235 | int rc9 = RTLockValidatorRecExclRecursion(&pThis->ValidatorRec, pSrcPos);
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236 | if (RT_FAILURE(rc9))
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237 | return rc9;
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238 | #endif
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239 | ASMAtomicIncU32(&pThis->cNestings);
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240 | return VINF_SUCCESS;
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241 | }
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242 |
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243 | #ifdef RTSEMMUTEX_STRICT
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244 | RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
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245 | if (cMillies)
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246 | {
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247 | int rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorRec, hThreadSelf, pSrcPos, cMillies);
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248 | if (RT_FAILURE(rc9))
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249 | return rc9;
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250 | }
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251 | #else
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252 | RTTHREAD hThreadSelf = RTThreadSelf();
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253 | #endif
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254 |
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255 | /*
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256 | * Convert timeout value.
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257 | */
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258 | struct timespec ts;
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259 | struct timespec *pTimeout = NULL;
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260 | uint64_t u64End = 0; /* shut up gcc */
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261 | if (cMillies != RT_INDEFINITE_WAIT)
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262 | {
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263 | ts.tv_sec = cMillies / 1000;
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264 | ts.tv_nsec = (cMillies % 1000) * UINT32_C(1000000);
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265 | u64End = RTTimeSystemNanoTS() + cMillies * UINT64_C(1000000);
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266 | pTimeout = &ts;
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267 | }
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268 |
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269 | /*
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270 | * Lock the mutex.
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271 | * Optimize for the uncontended case (makes 1-2 ns difference).
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272 | */
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273 | if (RT_UNLIKELY(!ASMAtomicCmpXchgS32(&pThis->iState, 1, 0)))
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274 | {
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275 | for (;;)
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276 | {
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277 | int32_t iOld = ASMAtomicXchgS32(&pThis->iState, 2);
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278 |
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279 | /*
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280 | * Was the lock released in the meantime? This is unlikely (but possible)
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281 | */
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282 | if (RT_UNLIKELY(iOld == 0))
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283 | break;
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284 |
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285 | /*
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286 | * Go to sleep.
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287 | */
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288 | if (pTimeout && ( pTimeout->tv_sec || pTimeout->tv_nsec ))
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289 | {
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290 | #ifdef RTSEMMUTEX_STRICT
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291 | int rc9 = RTLockValidatorRecExclCheckBlocking(&pThis->ValidatorRec, hThreadSelf, pSrcPos, true,
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292 | cMillies, RTTHREADSTATE_MUTEX, true);
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293 | if (RT_FAILURE(rc9))
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294 | return rc9;
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295 | #else
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296 | RTThreadBlocking(hThreadSelf, RTTHREADSTATE_MUTEX, true);
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297 | #endif
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298 | }
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299 |
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300 | long rc = sys_futex(&pThis->iState, FUTEX_WAIT, 2, pTimeout, NULL, 0);
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301 |
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302 | RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_MUTEX);
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303 | if (RT_UNLIKELY(pThis->u32Magic != RTSEMMUTEX_MAGIC))
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304 | return VERR_SEM_DESTROYED;
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305 |
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306 | /*
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307 | * Act on the wakup code.
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308 | */
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309 | if (rc == -ETIMEDOUT)
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310 | {
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311 | Assert(pTimeout);
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312 | return VERR_TIMEOUT;
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313 | }
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314 | if (rc == 0)
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315 | /* we'll leave the loop now unless another thread is faster */;
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316 | else if (rc == -EWOULDBLOCK)
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317 | /* retry with new value. */;
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318 | else if (rc == -EINTR)
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319 | {
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320 | if (!fAutoResume)
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321 | return VERR_INTERRUPTED;
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322 | }
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323 | else
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324 | {
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325 | /* this shouldn't happen! */
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326 | AssertMsgFailed(("rc=%ld errno=%d\n", rc, errno));
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327 | return RTErrConvertFromErrno(rc);
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328 | }
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329 |
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330 | /* adjust the relative timeout */
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331 | if (pTimeout)
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332 | {
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333 | int64_t i64Diff = u64End - RTTimeSystemNanoTS();
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334 | if (i64Diff < 1000)
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335 | {
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336 | rc = VERR_TIMEOUT;
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337 | break;
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338 | }
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339 | ts.tv_sec = (uint64_t)i64Diff / UINT32_C(1000000000);
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340 | ts.tv_nsec = (uint64_t)i64Diff % UINT32_C(1000000000);
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341 | }
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342 | }
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343 |
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344 | /*
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345 | * When leaving this loop, iState is set to 2. This means that we gained the
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346 | * lock and there are _possibly_ some waiters. We don't know exactly as another
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347 | * thread might entered this loop at nearly the same time. Therefore we will
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348 | * call futex_wakeup once too often (if _no_ other thread entered this loop).
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349 | * The key problem is the simple futex_wait test for x != y (iState != 2) in
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350 | * our case).
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351 | */
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352 | }
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353 |
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354 | /*
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355 | * Set the owner and nesting.
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356 | */
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357 | pThis->Owner = Self;
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358 | ASMAtomicWriteU32(&pThis->cNestings, 1);
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359 | #ifdef RTSEMMUTEX_STRICT
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360 | RTLockValidatorRecExclSetOwner(&pThis->ValidatorRec, hThreadSelf, pSrcPos, true);
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361 | #endif
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362 | return VINF_SUCCESS;
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363 | }
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364 |
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365 |
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366 | #undef RTSemMutexRequest
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367 | RTDECL(int) RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
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368 | {
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369 | #ifndef RTSEMMUTEX_STRICT
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370 | int rc = rtSemMutexRequest(hMutexSem, cMillies, true, NULL);
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371 | #else
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372 | RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
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373 | int rc = rtSemMutexRequest(hMutexSem, cMillies, true, &SrcPos);
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374 | #endif
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375 | Assert(rc != VERR_INTERRUPTED);
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376 | return rc;
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377 | }
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378 |
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379 |
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380 | RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
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381 | {
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382 | RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
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383 | int rc = rtSemMutexRequest(hMutexSem, cMillies, true, &SrcPos);
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384 | Assert(rc != VERR_INTERRUPTED);
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385 | return rc;
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386 | }
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387 |
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388 |
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389 | #undef RTSemMutexRequestNoResume
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390 | RTDECL(int) RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
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391 | {
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392 | #ifndef RTSEMMUTEX_STRICT
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393 | return rtSemMutexRequest(hMutexSem, cMillies, false, NULL);
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394 | #else
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395 | RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
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396 | return rtSemMutexRequest(hMutexSem, cMillies, false, &SrcPos);
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397 | #endif
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398 | }
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399 |
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400 |
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401 | RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
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402 | {
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403 | RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
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404 | return rtSemMutexRequest(hMutexSem, cMillies, false, &SrcPos);
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405 | }
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406 |
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407 |
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408 | RTDECL(int) RTSemMutexRelease(RTSEMMUTEX hMutexSem)
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409 | {
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410 | /*
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411 | * Validate input.
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412 | */
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413 | struct RTSEMMUTEXINTERNAL *pThis = hMutexSem;
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414 | AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
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415 | AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
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416 |
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417 | #ifdef RTSEMMUTEX_STRICT
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418 | int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorRec, pThis->cNestings == 1);
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419 | if (RT_FAILURE(rc9))
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420 | return rc9;
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421 | #endif
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422 |
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423 | /*
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424 | * Check if nested.
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425 | */
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426 | pthread_t Self = pthread_self();
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427 | if (RT_UNLIKELY( pThis->Owner != Self
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428 | || pThis->cNestings == 0))
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429 | {
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430 | AssertMsgFailed(("Not owner of mutex %p!! Self=%08x Owner=%08x cNestings=%d\n",
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431 | pThis, Self, pThis->Owner, pThis->cNestings));
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432 | return VERR_NOT_OWNER;
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433 | }
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434 |
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435 | /*
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436 | * If nested we'll just pop a nesting.
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437 | */
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438 | if (pThis->cNestings > 1)
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439 | {
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440 | ASMAtomicDecU32(&pThis->cNestings);
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441 | return VINF_SUCCESS;
|
---|
442 | }
|
---|
443 |
|
---|
444 | /*
|
---|
445 | * Clear the state. (cNestings == 1)
|
---|
446 | */
|
---|
447 | pThis->Owner = (pthread_t)~0;
|
---|
448 | ASMAtomicWriteU32(&pThis->cNestings, 0);
|
---|
449 |
|
---|
450 | /*
|
---|
451 | * Release the mutex.
|
---|
452 | */
|
---|
453 | int32_t iNew = ASMAtomicDecS32(&pThis->iState);
|
---|
454 | if (RT_UNLIKELY(iNew != 0))
|
---|
455 | {
|
---|
456 | /* somebody is waiting, try wake up one of them. */
|
---|
457 | ASMAtomicXchgS32(&pThis->iState, 0);
|
---|
458 | (void)sys_futex(&pThis->iState, FUTEX_WAKE, 1, NULL, NULL, 0);
|
---|
459 | }
|
---|
460 | return VINF_SUCCESS;
|
---|
461 | }
|
---|
462 |
|
---|
463 |
|
---|
464 | RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
|
---|
465 | {
|
---|
466 | /*
|
---|
467 | * Validate.
|
---|
468 | */
|
---|
469 | RTSEMMUTEXINTERNAL *pThis = hMutexSem;
|
---|
470 | AssertPtrReturn(pThis, false);
|
---|
471 | AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, false);
|
---|
472 |
|
---|
473 | return pThis->Owner != (pthread_t)~0;
|
---|
474 | }
|
---|
475 |
|
---|