/* $Id: semevent-linux.cpp $ */ /** @file * IPRT - Event Semaphore, Linux (2.6.x+). */ /* * Copyright (C) 2006-2019 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the * VirtualBox OSE 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. */ #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. We * will 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/semevent-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/mem.h" #include "internal/strict.h" #include #include #include #include #include #include #if 0 /* With 2.6.17 futex.h has become C++ unfriendly. */ # include #else # define FUTEX_WAIT 0 # define FUTEX_WAKE 1 #endif /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** * Linux (single wakup) event semaphore. */ struct RTSEMEVENTINTERNAL { /** Magic value. */ intptr_t volatile iMagic; /** The futex state variable. * 0 means not signalled. 1 means signalled. */ uint32_t volatile fSignalled; /** The number of waiting threads */ int32_t volatile cWaiters; #ifdef RTSEMEVENT_STRICT /** Signallers. */ RTLOCKVALRECSHRD Signallers; /** Indicates that lock validation should be performed. */ bool volatile fEverHadSignallers; #endif /** The creation flags. */ uint32_t fFlags; }; /** * Wrapper for the futex syscall. */ static long sys_futex(uint32_t volatile *uaddr, int op, int val, struct timespec *utime, int32_t *uaddr2, int val3) { errno = 0; long rc = syscall(__NR_futex, uaddr, op, val, utime, uaddr2, val3); if (rc < 0) { Assert(rc == -1); rc = -errno; } return rc; } RTDECL(int) RTSemEventCreate(PRTSEMEVENT phEventSem) { return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL); } RTDECL(int) RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...) { AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER); Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL)); /* * Allocate semaphore handle. */ struct RTSEMEVENTINTERNAL *pThis; if (!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)) pThis = (struct RTSEMEVENTINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTINTERNAL)); else pThis = (struct RTSEMEVENTINTERNAL *)rtMemBaseAlloc(sizeof(struct RTSEMEVENTINTERNAL)); if (pThis) { pThis->iMagic = RTSEMEVENT_MAGIC; pThis->cWaiters = 0; pThis->fSignalled = 0; pThis->fFlags = fFlags; #ifdef RTSEMEVENT_STRICT if (!pszNameFmt) { static uint32_t volatile s_iSemEventAnon = 0; RTLockValidatorRecSharedInit(&pThis->Signallers, hClass, RTLOCKVAL_SUB_CLASS_ANY, pThis, true /*fSignaller*/, !(fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL), "RTSemEvent-%u", ASMAtomicIncU32(&s_iSemEventAnon) - 1); } else { va_list va; va_start(va, pszNameFmt); RTLockValidatorRecSharedInitV(&pThis->Signallers, hClass, RTLOCKVAL_SUB_CLASS_ANY, pThis, true /*fSignaller*/, !(fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL), pszNameFmt, va); va_end(va); } pThis->fEverHadSignallers = false; #else RT_NOREF(hClass, pszNameFmt); #endif *phEventSem = pThis; return VINF_SUCCESS; } return VERR_NO_MEMORY; } RTDECL(int) RTSemEventDestroy(RTSEMEVENT hEventSem) { /* * Validate input. */ struct RTSEMEVENTINTERNAL *pThis = hEventSem; if (pThis == NIL_RTSEMEVENT) return VINF_SUCCESS; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE); /* * Invalidate the semaphore and wake up anyone waiting on it. */ ASMAtomicXchgSize(&pThis->iMagic, RTSEMEVENT_MAGIC | UINT32_C(0x80000000)); if (ASMAtomicXchgS32(&pThis->cWaiters, INT32_MIN / 2) > 0) { sys_futex(&pThis->fSignalled, FUTEX_WAKE, INT_MAX, NULL, NULL, 0); usleep(1000); } /* * Free the semaphore memory and be gone. */ #ifdef RTSEMEVENT_STRICT RTLockValidatorRecSharedDelete(&pThis->Signallers); #endif if (!(pThis->fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)) RTMemFree(pThis); else rtMemBaseFree(pThis); return VINF_SUCCESS; } RTDECL(int) RTSemEventSignal(RTSEMEVENT hEventSem) { /* * Validate input. */ struct RTSEMEVENTINTERNAL *pThis = hEventSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE); #ifdef RTSEMEVENT_STRICT if (pThis->fEverHadSignallers) { int rc9 = RTLockValidatorRecSharedCheckSignaller(&pThis->Signallers, NIL_RTTHREAD); if (RT_FAILURE(rc9)) return rc9; } #endif ASMAtomicWriteU32(&pThis->fSignalled, 1); if (ASMAtomicReadS32(&pThis->cWaiters) < 1) return VINF_SUCCESS; /* somebody is waiting, try wake up one of them. */ long cWoken = sys_futex(&pThis->fSignalled, FUTEX_WAKE, 1, NULL, NULL, 0); if (RT_LIKELY(cWoken >= 0)) return VINF_SUCCESS; if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC)) return VERR_SEM_DESTROYED; return VERR_INVALID_PARAMETER; } static int rtSemEventWait(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies, bool fAutoResume) { #ifdef RTSEMEVENT_STRICT PCRTLOCKVALSRCPOS pSrcPos = NULL; #endif /* * Validate input. */ struct RTSEMEVENTINTERNAL *pThis = hEventSem; AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE); /* * Quickly check whether it's signaled. */ /** @todo this isn't fair if someone is already waiting on it. They should * have the first go at it! * (ASMAtomicReadS32(&pThis->cWaiters) == 0 || !cMillies) && ... */ if (ASMAtomicCmpXchgU32(&pThis->fSignalled, 0, 1)) return VINF_SUCCESS; /* * Convert the timeout value. */ struct timespec ts; struct timespec *pTimeout = NULL; uint64_t u64End = 0; /* shut up gcc */ if (cMillies != RT_INDEFINITE_WAIT) { if (!cMillies) return VERR_TIMEOUT; ts.tv_sec = cMillies / 1000; ts.tv_nsec = (cMillies % 1000) * UINT32_C(1000000); u64End = RTTimeSystemNanoTS() + cMillies * UINT64_C(1000000); pTimeout = &ts; } ASMAtomicIncS32(&pThis->cWaiters); /* * The wait loop. */ #ifdef RTSEMEVENT_STRICT RTTHREAD hThreadSelf = !(pThis->fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) ? RTThreadSelfAutoAdopt() : RTThreadSelf(); #else RTTHREAD hThreadSelf = RTThreadSelf(); #endif int rc = VINF_SUCCESS; for (;;) { #ifdef RTSEMEVENT_STRICT if (pThis->fEverHadSignallers) { rc = RTLockValidatorRecSharedCheckBlocking(&pThis->Signallers, hThreadSelf, pSrcPos, false, cMillies, RTTHREADSTATE_EVENT, true); if (RT_FAILURE(rc)) break; } #endif RTThreadBlocking(hThreadSelf, RTTHREADSTATE_EVENT, true); long lrc = sys_futex(&pThis->fSignalled, FUTEX_WAIT, 0, pTimeout, NULL, 0); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_EVENT); if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC)) { rc = VERR_SEM_DESTROYED; break; } if (RT_LIKELY(lrc == 0 || lrc == -EWOULDBLOCK)) { /* successful wakeup or fSignalled > 0 in the meantime */ if (ASMAtomicCmpXchgU32(&pThis->fSignalled, 0, 1)) break; } else if (lrc == -ETIMEDOUT) { rc = VERR_TIMEOUT; break; } else if (lrc == -EINTR) { if (!fAutoResume) { rc = VERR_INTERRUPTED; break; } } else { /* this shouldn't happen! */ AssertMsgFailed(("rc=%ld errno=%d\n", lrc, errno)); rc = RTErrConvertFromErrno(lrc); break; } /* adjust the relative timeout */ if (pTimeout) { int64_t i64Diff = u64End - RTTimeSystemNanoTS(); if (i64Diff < 1000) { rc = VERR_TIMEOUT; break; } ts.tv_sec = (uint64_t)i64Diff / UINT32_C(1000000000); ts.tv_nsec = (uint64_t)i64Diff % UINT32_C(1000000000); } } ASMAtomicDecS32(&pThis->cWaiters); return rc; } RTDECL(int) RTSemEventWait(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies) { int rc = rtSemEventWait(hEventSem, cMillies, true); Assert(rc != VERR_INTERRUPTED); Assert(rc != VERR_TIMEOUT || cMillies != RT_INDEFINITE_WAIT); return rc; } RTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies) { return rtSemEventWait(hEventSem, cMillies, false); } RTDECL(void) RTSemEventSetSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread) { #ifdef RTSEMEVENT_STRICT struct RTSEMEVENTINTERNAL *pThis = hEventSem; AssertPtrReturnVoid(pThis); AssertReturnVoid(pThis->iMagic == RTSEMEVENT_MAGIC); ASMAtomicWriteBool(&pThis->fEverHadSignallers, true); RTLockValidatorRecSharedResetOwner(&pThis->Signallers, hThread, NULL); #else RT_NOREF(hEventSem, hThread); #endif } RTDECL(void) RTSemEventAddSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread) { #ifdef RTSEMEVENT_STRICT struct RTSEMEVENTINTERNAL *pThis = hEventSem; AssertPtrReturnVoid(pThis); AssertReturnVoid(pThis->iMagic == RTSEMEVENT_MAGIC); ASMAtomicWriteBool(&pThis->fEverHadSignallers, true); RTLockValidatorRecSharedAddOwner(&pThis->Signallers, hThread, NULL); #else RT_NOREF(hEventSem, hThread); #endif } RTDECL(void) RTSemEventRemoveSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread) { #ifdef RTSEMEVENT_STRICT struct RTSEMEVENTINTERNAL *pThis = hEventSem; AssertPtrReturnVoid(pThis); AssertReturnVoid(pThis->iMagic == RTSEMEVENT_MAGIC); RTLockValidatorRecSharedRemoveOwner(&pThis->Signallers, hThread); #else RT_NOREF(hEventSem, hThread); #endif } #endif /* glibc < 2.6 || IPRT_WITH_FUTEX_BASED_SEMS */