/* $Id: semeventmulti-linux.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */ /** @file * IPRT - Multiple Release Event Semaphore, Linux (2.6.x+). */ /* * Copyright (C) 2006-2023 Oracle and/or its affiliates. * * This file is part of VirtualBox base platform packages, as * available from https://www.virtualbox.org. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation, in version 3 of the * License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included * in the VirtualBox distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. * * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 */ #include #if __GLIBC_PREREQ(2,6) && !defined(IPRT_WITH_FUTEX_BASED_SEMS) /* * glibc 2.6 fixed a serious bug in the mutex implementation. We wrote this * linux specific event semaphores code in order to work around the bug. As it * turns out, this code seems to have an unresolved issue (@bugref{2599}), so we'll * fall back on the pthread based implementation if glibc is known to contain * the bug fix. * * The external reference to epoll_pwait is a hack which prevents that we link * against glibc < 2.6. */ #include "../posix/semeventmulti-posix.cpp" __asm__ (".global epoll_pwait"); #else /* glibc < 2.6 */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #include #include "internal/iprt.h" #include #include #include #include #include #include #include "internal/magics.h" #include "internal/strict.h" #include #include #include #include #include #include #include "semwait-linux.h" /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** * Linux multiple wakup event semaphore. */ struct RTSEMEVENTMULTIINTERNAL { /** Magic value. */ uint32_t volatile u32Magic; /** The futex state variable, see RTSEMEVENTMULTI_LNX_XXX. */ uint32_t volatile uState; #ifdef RT_STRICT /** Increased on every signalling call. */ uint32_t volatile uSignalSerialNo; #endif #ifdef RTSEMEVENTMULTI_STRICT /** Signallers. */ RTLOCKVALRECSHRD Signallers; /** Indicates that lock validation should be performed. */ bool volatile fEverHadSignallers; #endif }; /********************************************************************************************************************************* * Defined Constants And Macros * *********************************************************************************************************************************/ /** @name RTSEMEVENTMULTI_LNX_XXX - state * @{ */ #define RTSEMEVENTMULTI_LNX_NOT_SIGNALED UINT32_C(0x00000000) #define RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS UINT32_C(0x00000001) #define RTSEMEVENTMULTI_LNX_SIGNALED UINT32_C(0x00000003) /** @} */ #define ASSERT_VALID_STATE(a_uState) \ AssertMsg( (a_uState) == RTSEMEVENTMULTI_LNX_NOT_SIGNALED \ || (a_uState) == RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS \ || (a_uState) == RTSEMEVENTMULTI_LNX_SIGNALED, \ (#a_uState "=%s\n", a_uState)) /********************************************************************************************************************************* * Global Variables * *********************************************************************************************************************************/ /** Whether we can use FUTEX_WAIT_BITSET. */ static int volatile g_fCanUseWaitBitSet = -1; RTDECL(int) RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem) { return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL); } RTDECL(int) RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...) { AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER); /* * Make sure we know whether FUTEX_WAIT_BITSET works. */ rtSemLinuxCheckForFutexWaitBitSet(&g_fCanUseWaitBitSet); #if defined(DEBUG_bird) && !defined(IN_GUEST) Assert(g_fCanUseWaitBitSet == true); #endif /* * Allocate semaphore handle. */ struct RTSEMEVENTMULTIINTERNAL *pThis = (struct RTSEMEVENTMULTIINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTMULTIINTERNAL)); if (pThis) { pThis->u32Magic = RTSEMEVENTMULTI_MAGIC; pThis->uState = RTSEMEVENTMULTI_LNX_NOT_SIGNALED; #ifdef RT_STRICT pThis->uSignalSerialNo = 0; #endif #ifdef RTSEMEVENTMULTI_STRICT if (!pszNameFmt) { static uint32_t volatile s_iSemEventMultiAnon = 0; RTLockValidatorRecSharedInit(&pThis->Signallers, hClass, RTLOCKVAL_SUB_CLASS_ANY, pThis, true /*fSignaller*/, !(fFlags & RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), "RTSemEventMulti-%u", ASMAtomicIncU32(&s_iSemEventMultiAnon) - 1); } else { va_list va; va_start(va, pszNameFmt); RTLockValidatorRecSharedInitV(&pThis->Signallers, hClass, RTLOCKVAL_SUB_CLASS_ANY, pThis, true /*fSignaller*/, !(fFlags & RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), pszNameFmt, va); va_end(va); } pThis->fEverHadSignallers = false; #else RT_NOREF(hClass, pszNameFmt); #endif *phEventMultiSem = pThis; return VINF_SUCCESS; } return VERR_NO_MEMORY; } RTDECL(int) RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem) { /* * Validate input. */ struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; if (pThis == NIL_RTSEMEVENTMULTI) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, VERR_INVALID_HANDLE); /* * Invalidate the semaphore and wake up anyone waiting on it. */ ASMAtomicWriteU32(&pThis->u32Magic, RTSEMEVENTMULTI_MAGIC + 1); if (ASMAtomicXchgU32(&pThis->uState, RTSEMEVENTMULTI_LNX_SIGNALED) == RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS) { sys_futex(&pThis->uState, FUTEX_WAKE, INT_MAX, NULL, NULL, 0); usleep(1000); } /* * Free the semaphore memory and be gone. */ #ifdef RTSEMEVENTMULTI_STRICT RTLockValidatorRecSharedDelete(&pThis->Signallers); #endif RTMemFree(pThis); return VINF_SUCCESS; } RTDECL(int) RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem) { /* * Validate input. */ struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, VERR_INVALID_HANDLE); #ifdef RTSEMEVENTMULTI_STRICT if (pThis->fEverHadSignallers) { int rc9 = RTLockValidatorRecSharedCheckSignaller(&pThis->Signallers, NIL_RTTHREAD); if (RT_FAILURE(rc9)) return rc9; } #endif /* * Signal it. */ #ifdef RT_STRICT ASMAtomicIncU32(&pThis->uSignalSerialNo); #endif uint32_t uOld = ASMAtomicXchgU32(&pThis->uState, RTSEMEVENTMULTI_LNX_SIGNALED); if (uOld == RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS) { /* wake up sleeping threads. */ long cWoken = sys_futex(&pThis->uState, FUTEX_WAKE, INT_MAX, NULL, NULL, 0); AssertMsg(cWoken >= 0, ("%ld\n", cWoken)); NOREF(cWoken); } ASSERT_VALID_STATE(uOld); return VINF_SUCCESS; } RTDECL(int) RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem) { /* * Validate input. */ struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, VERR_INVALID_HANDLE); #ifdef RT_STRICT uint32_t const uState = pThis->uState; ASSERT_VALID_STATE(uState); #endif /* * Reset it. */ ASMAtomicCmpXchgU32(&pThis->uState, RTSEMEVENTMULTI_LNX_NOT_SIGNALED, RTSEMEVENTMULTI_LNX_SIGNALED); return VINF_SUCCESS; } /** * Performs an indefinite wait on the event. */ static int rtSemEventMultiLinuxWaitIndefinite(struct RTSEMEVENTMULTIINTERNAL *pThis, uint32_t fFlags, PCRTLOCKVALSRCPOS pSrcPos) { RT_NOREF(pSrcPos); /* * Quickly check whether it's signaled. */ uint32_t uState = ASMAtomicUoReadU32(&pThis->uState); if (uState == RTSEMEVENTMULTI_LNX_SIGNALED) return VINF_SUCCESS; ASSERT_VALID_STATE(uState); /* * The wait loop. */ #ifdef RTSEMEVENTMULTI_STRICT RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt(); #else RTTHREAD hThreadSelf = RTThreadSelf(); #endif for (unsigned i = 0;; i++) { /* * Start waiting. We only account for there being or having been * threads waiting on the semaphore to keep things simple. */ uState = ASMAtomicUoReadU32(&pThis->uState); if ( uState == RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS || ( uState == RTSEMEVENTMULTI_LNX_NOT_SIGNALED && ASMAtomicCmpXchgU32(&pThis->uState, RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS, RTSEMEVENTMULTI_LNX_NOT_SIGNALED))) { #ifdef RTSEMEVENTMULTI_STRICT if (pThis->fEverHadSignallers) { int rc9 = RTLockValidatorRecSharedCheckBlocking(&pThis->Signallers, hThreadSelf, pSrcPos, false, RT_INDEFINITE_WAIT, RTTHREADSTATE_EVENT_MULTI, true); if (RT_FAILURE(rc9)) return rc9; } #endif #ifdef RT_STRICT uint32_t const uPrevSignalSerialNo = ASMAtomicReadU32(&pThis->uSignalSerialNo); #endif RTThreadBlocking(hThreadSelf, RTTHREADSTATE_EVENT_MULTI, true); long rc = sys_futex(&pThis->uState, FUTEX_WAIT, 1, NULL /*pTimeout*/, NULL, 0); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_EVENT_MULTI); /* Check that the structure is still alive before continuing. */ if (RT_LIKELY(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC)) { /*likely*/ } else return VERR_SEM_DESTROYED; /* * Return if success. */ if (rc == 0) { Assert(uPrevSignalSerialNo != ASMAtomicReadU32(&pThis->uSignalSerialNo)); return VINF_SUCCESS; } /* * Act on the wakup code. */ if (rc == -EWOULDBLOCK) /* retry, the value changed. */; else if (rc == -EINTR) { if (fFlags & RTSEMWAIT_FLAGS_NORESUME) return VERR_INTERRUPTED; } else { /* this shouldn't happen! */ AssertMsgFailed(("rc=%ld errno=%d\n", rc, errno)); return RTErrConvertFromErrno(rc); } } else if (uState == RTSEMEVENTMULTI_LNX_SIGNALED) return VINF_SUCCESS; else ASSERT_VALID_STATE(uState); } } /** * Handle polling (timeout already expired at the time of the call). * * @returns VINF_SUCCESS, VERR_TIMEOUT, VERR_SEM_DESTROYED. * @param pThis The semaphore. */ static int rtSemEventMultiLinuxWaitPoll(struct RTSEMEVENTMULTIINTERNAL *pThis) { uint32_t uState = ASMAtomicUoReadU32(&pThis->uState); if (uState == RTSEMEVENTMULTI_LNX_SIGNALED) return VINF_SUCCESS; return VERR_TIMEOUT; } /** * Performs an indefinite wait on the event. */ static int rtSemEventMultiLinuxWaitTimed(struct RTSEMEVENTMULTIINTERNAL *pThis, uint32_t fFlags, uint64_t uTimeout, PCRTLOCKVALSRCPOS pSrcPos) { RT_NOREF(pSrcPos); /* * Quickly check whether it's signaled. */ uint32_t uState = ASMAtomicUoReadU32(&pThis->uState); if (uState == RTSEMEVENTMULTI_LNX_SIGNALED) return VINF_SUCCESS; ASSERT_VALID_STATE(uState); /* * Convert the timeout value. */ struct timespec TsTimeout; int iWaitOp; uint32_t uWaitVal3; uint64_t nsAbsTimeout = uTimeout; /* (older gcc maybe used uninitialized) */ uTimeout = rtSemLinuxCalcDeadline(fFlags, uTimeout, g_fCanUseWaitBitSet, &TsTimeout, &iWaitOp, &uWaitVal3, &nsAbsTimeout); if (uTimeout == 0) return rtSemEventMultiLinuxWaitPoll(pThis); if (uTimeout == UINT64_MAX) return rtSemEventMultiLinuxWaitIndefinite(pThis, fFlags, pSrcPos); /* * The wait loop. */ #ifdef RTSEMEVENTMULTI_STRICT RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt(); #else RTTHREAD hThreadSelf = RTThreadSelf(); #endif for (unsigned i = 0;; i++) { /* * Start waiting. We only account for there being or having been * threads waiting on the semaphore to keep things simple. */ uState = ASMAtomicUoReadU32(&pThis->uState); if ( uState == RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS || ( uState == RTSEMEVENTMULTI_LNX_NOT_SIGNALED && ASMAtomicCmpXchgU32(&pThis->uState, RTSEMEVENTMULTI_LNX_NOT_SIGNALED_WAITERS, RTSEMEVENTMULTI_LNX_NOT_SIGNALED))) { #ifdef RTSEMEVENTMULTI_STRICT if (pThis->fEverHadSignallers) { int rc9 = RTLockValidatorRecSharedCheckBlocking(&pThis->Signallers, hThreadSelf, pSrcPos, false, uTimeout / UINT32_C(1000000), RTTHREADSTATE_EVENT_MULTI, true); if (RT_FAILURE(rc9)) return rc9; } #endif #ifdef RT_STRICT uint32_t const uPrevSignalSerialNo = ASMAtomicReadU32(&pThis->uSignalSerialNo); #endif RTThreadBlocking(hThreadSelf, RTTHREADSTATE_EVENT_MULTI, true); long rc = sys_futex(&pThis->uState, iWaitOp, 1, &TsTimeout, NULL, uWaitVal3); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_EVENT_MULTI); /* Check that the structure is still alive before continuing. */ if (RT_LIKELY(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC)) { /*likely*/ } else return VERR_SEM_DESTROYED; /* * Return if success. */ if (rc == 0) { Assert(uPrevSignalSerialNo != ASMAtomicReadU32(&pThis->uSignalSerialNo)); return VINF_SUCCESS; } /* * Act on the wakup code. */ if (rc == -ETIMEDOUT) { /** @todo something is broken here. shows up every now and again in the ata * code. Should try to run the timeout against RTTimeMilliTS to * check that it's doing the right thing... */ #ifdef RT_STRICT uint64_t const uNow = RTTimeNanoTS(); AssertMsg(uNow >= nsAbsTimeout || nsAbsTimeout - uNow < RT_NS_1MS, ("%#RX64 - %#RX64 => %#RX64 (%RI64)\n", nsAbsTimeout, uNow, nsAbsTimeout - uNow, nsAbsTimeout - uNow)); #endif return VERR_TIMEOUT; } if (rc == -EWOULDBLOCK) { /* retry, the value changed. */; } else if (rc == -EINTR) { if (fFlags & RTSEMWAIT_FLAGS_NORESUME) return VERR_INTERRUPTED; } else { /* this shouldn't happen! */ AssertMsgFailed(("rc=%ld errno=%d\n", rc, errno)); return RTErrConvertFromErrno(rc); } } else if (uState == RTSEMEVENTMULTI_LNX_SIGNALED) return VINF_SUCCESS; else ASSERT_VALID_STATE(uState); /* adjust the relative timeout if relative */ if (iWaitOp == FUTEX_WAIT) { int64_t i64Diff = nsAbsTimeout - RTTimeSystemNanoTS(); if (i64Diff < 1000) return VERR_TIMEOUT; TsTimeout.tv_sec = (uint64_t)i64Diff / RT_NS_1SEC; TsTimeout.tv_nsec = (uint64_t)i64Diff % RT_NS_1SEC; } } } /** * Internal wait worker function. */ DECLINLINE(int) rtSemEventLnxMultiWait(RTSEMEVENTMULTI hEventSem, uint32_t fFlags, uint64_t uTimeout, PCRTLOCKVALSRCPOS pSrcPos) { /* * Validate input. */ struct RTSEMEVENTMULTIINTERNAL *pThis = hEventSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, VERR_INVALID_HANDLE); AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER); /* * Timed or indefinite wait? */ if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE) return rtSemEventMultiLinuxWaitIndefinite(pThis, fFlags, pSrcPos); return rtSemEventMultiLinuxWaitTimed(hEventSem, fFlags, uTimeout, pSrcPos); } #undef RTSemEventMultiWaitEx RTDECL(int) RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout) { #ifndef RTSEMEVENT_STRICT return rtSemEventLnxMultiWait(hEventMultiSem, fFlags, uTimeout, NULL); #else RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API(); return rtSemEventLnxMultiWait(hEventMultiSem, fFlags, uTimeout, &SrcPos); #endif } RTDECL(int) RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout, RTHCUINTPTR uId, RT_SRC_POS_DECL) { RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API(); return rtSemEventLnxMultiWait(hEventMultiSem, fFlags, uTimeout, &SrcPos); } RTDECL(void) RTSemEventMultiSetSignaller(RTSEMEVENTMULTI hEventMultiSem, RTTHREAD hThread) { #ifdef RTSEMEVENTMULTI_STRICT struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; AssertPtrReturnVoid(pThis); AssertReturnVoid(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC); ASMAtomicWriteBool(&pThis->fEverHadSignallers, true); RTLockValidatorRecSharedResetOwner(&pThis->Signallers, hThread, NULL); #else RT_NOREF(hEventMultiSem, hThread); #endif } RTDECL(void) RTSemEventMultiAddSignaller(RTSEMEVENTMULTI hEventMultiSem, RTTHREAD hThread) { #ifdef RTSEMEVENTMULTI_STRICT struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; AssertPtrReturnVoid(pThis); AssertReturnVoid(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC); ASMAtomicWriteBool(&pThis->fEverHadSignallers, true); RTLockValidatorRecSharedAddOwner(&pThis->Signallers, hThread, NULL); #else RT_NOREF(hEventMultiSem, hThread); #endif } RTDECL(void) RTSemEventMultiRemoveSignaller(RTSEMEVENTMULTI hEventMultiSem, RTTHREAD hThread) { #ifdef RTSEMEVENTMULTI_STRICT struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; AssertPtrReturnVoid(pThis); AssertReturnVoid(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC); RTLockValidatorRecSharedRemoveOwner(&pThis->Signallers, hThread); #else RT_NOREF(hEventMultiSem, hThread); #endif } #endif /* glibc < 2.6 || IPRT_WITH_FUTEX_BASED_SEMS */