/* $Id: semeventmulti-linux.cpp 33540 2010-10-28 09:27:05Z vboxsync $ */ /** @file * IPRT - Multiple Release Event Semaphore, Linux (2.6.x+). */ /* * Copyright (C) 2006-2010 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. As it * turns out, this code seems to have an unresolved issue (#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 volatile (".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 #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 multiple wakup event semaphore. */ struct RTSEMEVENTMULTIINTERNAL { /** Magic value. */ uint32_t volatile u32Magic; /** The futex state variable. * -1 means signaled. * 0 means not signaled, no waiters. * 1 means not signaled and that someone is waiting. */ int32_t volatile iState; #ifdef RTSEMEVENTMULTI_STRICT /** Signallers. */ RTLOCKVALRECSHRD Signallers; /** Indicates that lock validation should be performed. */ bool volatile fEverHadSignallers; #endif }; /** * Wrapper for the futex syscall. */ static long sys_futex(int32_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) 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); /* * Allocate semaphore handle. */ struct RTSEMEVENTMULTIINTERNAL *pThis = (struct RTSEMEVENTMULTIINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTMULTIINTERNAL)); if (pThis) { pThis->u32Magic = RTSEMEVENTMULTI_MAGIC; pThis->iState = 0; #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; #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. */ ASMAtomicWriteSize(&pThis->u32Magic, RTSEMEVENTMULTI_MAGIC + 1); if (ASMAtomicXchgS32(&pThis->iState, -1) == 1) { sys_futex(&pThis->iState, 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; AssertReturn(VALID_PTR(pThis) && 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. */ int32_t iOld = ASMAtomicXchgS32(&pThis->iState, -1); if (iOld > 0) { /* wake up sleeping threads. */ long cWoken = sys_futex(&pThis->iState, FUTEX_WAKE, INT_MAX, NULL, NULL, 0); AssertMsg(cWoken >= 0, ("%ld\n", cWoken)); NOREF(cWoken); } Assert(iOld == 0 || iOld == -1 || iOld == 1); return VINF_SUCCESS; } RTDECL(int) RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem) { /* * Validate input. */ struct RTSEMEVENTMULTIINTERNAL *pThis = hEventMultiSem; AssertReturn(VALID_PTR(pThis) && pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, VERR_INVALID_HANDLE); #ifdef RT_STRICT int32_t i = pThis->iState; Assert(i == 0 || i == -1 || i == 1); #endif /* * Reset it. */ ASMAtomicCmpXchgS32(&pThis->iState, 0, -1); return VINF_SUCCESS; } DECLINLINE(int) rtSemEventLnxMultiWait(struct RTSEMEVENTMULTIINTERNAL *pThis, uint32_t fFlags, uint64_t uTimeout, PCRTLOCKVALSRCPOS pSrcPos) { /* * Validate input. */ AssertPtrReturn(pThis, VERR_INVALID_HANDLE); AssertReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, VERR_INVALID_HANDLE); AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER); /* * Quickly check whether it's signaled. */ int32_t iCur = ASMAtomicUoReadS32(&pThis->iState); Assert(iCur == 0 || iCur == -1 || iCur == 1); if (iCur == -1) return VINF_SUCCESS; /* * Check and convert the timeout value. */ struct timespec ts; struct timespec *pTimeout = NULL; uint64_t u64Deadline = 0; /* shut up gcc */ if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE)) { /* If the timeout is zero, then we're done. */ if (!uTimeout) return VERR_TIMEOUT; /* Convert it to a deadline + interval timespec. */ if (fFlags & RTSEMWAIT_FLAGS_MILLISECS) uTimeout = uTimeout < UINT64_MAX / UINT32_C(1000000) * UINT32_C(1000000) ? uTimeout * UINT32_C(1000000) : UINT64_MAX; if (uTimeout != UINT64_MAX) /* unofficial way of indicating an indefinite wait */ { if (fFlags & RTSEMWAIT_FLAGS_RELATIVE) u64Deadline = RTTimeSystemNanoTS() + uTimeout; else { uint64_t u64Now = RTTimeSystemNanoTS(); if (uTimeout <= u64Now) return VERR_TIMEOUT; u64Deadline = uTimeout; uTimeout -= u64Now; } if ( sizeof(ts.tv_sec) >= sizeof(uint64_t) || uTimeout <= UINT64_C(1000000000) * UINT32_MAX) { ts.tv_nsec = uTimeout % UINT32_C(1000000000); ts.tv_sec = uTimeout / UINT32_C(1000000000); pTimeout = &ts; } } } /* * 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. */ iCur = ASMAtomicUoReadS32(&pThis->iState); Assert(iCur == 0 || iCur == -1 || iCur == 1); if ( iCur == 1 || ASMAtomicCmpXchgS32(&pThis->iState, 1, 0)) { /* adjust the relative timeout */ if (pTimeout) { int64_t i64Diff = u64Deadline - RTTimeSystemNanoTS(); if (i64Diff < 1000) return VERR_TIMEOUT; ts.tv_sec = (uint64_t)i64Diff / UINT32_C(1000000000); ts.tv_nsec = (uint64_t)i64Diff % UINT32_C(1000000000); } #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 RTThreadBlocking(hThreadSelf, RTTHREADSTATE_EVENT_MULTI, true); long rc = sys_futex(&pThis->iState, FUTEX_WAIT, 1, pTimeout, NULL, 0); RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_EVENT_MULTI); if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC)) return VERR_SEM_DESTROYED; if (rc == 0) 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... */ Assert(pTimeout); 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 (iCur == -1) return VINF_SUCCESS; } } #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); #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); #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); #endif } #endif /* glibc < 2.6 || IPRT_WITH_FUTEX_BASED_SEMS */