semevent-linux.cpp revision 0a7b20727716a00270f358a1c546473d8c36e8f3
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/* $Id$ */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/** @file
5b281ba489ca18f0380d7efc7a5108b606cce449vboxsync * IPRT - Event Semaphore, Linux (2.6.x+).
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/*
1c94c0a63ba68be1a7b2c640e70d7a06464e4fcavboxsync * Copyright (C) 2006-2007 Sun Microsystems, Inc.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * This file is part of VirtualBox Open Source Edition (OSE), as
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * available from http://www.virtualbox.org. This file is free software;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * you can redistribute it and/or modify it under the terms of the GNU
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * General Public License (GPL) as published by the Free Software
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Foundation, in version 2 as it comes in the "COPYING" file of the
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * The contents of this file may alternatively be used under the terms
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * of the Common Development and Distribution License Version 1.0
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * VirtualBox OSE distribution, in which case the provisions of the
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * CDDL are applicable instead of those of the GPL.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * You may elect to license modified versions of this file under the
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * terms and conditions of either the GPL or the CDDL or both.
1c94c0a63ba68be1a7b2c640e70d7a06464e4fcavboxsync *
1c94c0a63ba68be1a7b2c640e70d7a06464e4fcavboxsync * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
1c94c0a63ba68be1a7b2c640e70d7a06464e4fcavboxsync * Clara, CA 95054 USA or visit http://www.sun.com if you need
1c94c0a63ba68be1a7b2c640e70d7a06464e4fcavboxsync * additional information or have any questions.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync#include <features.h>
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync#if __GLIBC_PREREQ(2,6)
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync/*
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * glibc 2.6 fixed a serious bug in the mutex implementation. We wrote this
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * linux specific event semaphores code in order to work around the bug. As it
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * turns out, this code seems to have an unresolved issue (#2599), so we'll
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * fall back on the pthread based implementation if glibc is known to contain
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * the bug fix.
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync *
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * The external refernce to epoll_pwait is a hack which prevents that we link
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * against glibc < 2.6.
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync */
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync#include "../posix/semevent-posix.cpp"
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsyncasm volatile (".global epoll_pwait");
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync#else /* glibc < 2.6 */
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/*******************************************************************************
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync* Header Files *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync*******************************************************************************/
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <iprt/semaphore.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <iprt/assert.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <iprt/alloc.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <iprt/asm.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <iprt/err.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include "internal/magics.h"
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <errno.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <limits.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <pthread.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <unistd.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <sys/time.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#include <sys/syscall.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#if 0 /* With 2.6.17 futex.h has become C++ unfriendly. */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync# include <linux/futex.h>
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#else
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync# define FUTEX_WAIT 0
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync# define FUTEX_WAKE 1
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#endif
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/*******************************************************************************
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync* Structures and Typedefs *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync*******************************************************************************/
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/**
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Linux (single wakup) event semaphore.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncstruct RTSEMEVENTINTERNAL
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /** Magic value. */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync intptr_t volatile iMagic;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /** The futex state variable.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * <0 means signaled.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * 0 means not signaled, no waiters.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * >0 means not signaled, and the value gives the number of waiters.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync int32_t volatile cWaiters;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync};
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/**
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Wrapper for the futex syscall.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncstatic long sys_futex(int32_t volatile *uaddr, int op, int val, struct timespec *utime, int32_t *uaddr2, int val3)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync errno = 0;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync long rc = syscall(__NR_futex, uaddr, op, val, utime, uaddr2, val3);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (rc < 0)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync Assert(rc == -1);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync rc = -errno;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return rc;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventCreate(PRTSEMEVENT pEventSem)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Allocate semaphore handle.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync struct RTSEMEVENTINTERNAL *pThis = (struct RTSEMEVENTINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTINTERNAL));
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync if (pThis)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync pThis->iMagic = RTSEMEVENT_MAGIC;
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync pThis->cWaiters = 0;
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync *pEventSem = pThis;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VINF_SUCCESS;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VERR_NO_MEMORY;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventDestroy(RTSEMEVENT EventSem)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Validate input.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
660fd430a3a8cfa16505d04c7c577acf89d45a40vboxsync if (EventSem == NIL_RTSEMEVENT) /* don't bitch */
660fd430a3a8cfa16505d04c7c577acf89d45a40vboxsync return VERR_INVALID_HANDLE;
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync struct RTSEMEVENTINTERNAL *pThis = EventSem;
660fd430a3a8cfa16505d04c7c577acf89d45a40vboxsync AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
660fd430a3a8cfa16505d04c7c577acf89d45a40vboxsync AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Invalidate the semaphore and wake up anyone waiting on it.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync ASMAtomicXchgSize(&pThis->iMagic, RTSEMEVENT_MAGIC | UINT32_C(0x80000000));
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync if (ASMAtomicXchgS32(&pThis->cWaiters, INT32_MIN / 2) > 0)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync sys_futex(&pThis->cWaiters, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync usleep(1000);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Free the semaphore memory and be gone.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync RTMemFree(pThis);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VINF_SUCCESS;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventSignal(RTSEMEVENT EventSem)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Validate input.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync struct RTSEMEVENTINTERNAL *pThis = EventSem;
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync AssertReturn(VALID_PTR(pThis) && pThis->iMagic == RTSEMEVENT_MAGIC,
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync VERR_INVALID_HANDLE);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Try signal it.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync for (unsigned i = 0;; i++)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync int32_t iCur;
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync if (ASMAtomicCmpXchgExS32(&pThis->cWaiters, -1, 0, &iCur))
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync break; /* nobody is waiting */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else if (iCur < 0)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync break; /* already signaled */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /* somebody is waiting, try wake up one of them. */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync long cWoken = sys_futex(&pThis->cWaiters, FUTEX_WAKE, 1, NULL, NULL, 0);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (RT_LIKELY(cWoken == 1))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync ASMAtomicDecS32(&pThis->cWaiters);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync break;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync AssertMsg(cWoken == 0, ("%ld\n", cWoken));
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * This path is taken in two situations:
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * 1) A waiting thread is returning from the sys_futex call with a
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * non-zero return value.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * 2) There are two threads signaling the event at the
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * same time and only one thread waiting.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * At this point we know that nobody is activly waiting on the event but
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * at the same time, we are racing someone updating the state. The current
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * strategy is to spin till the thread racing us is done, this is kind of
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * brain dead and need fixing of course.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (RT_UNLIKELY(i > 32))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if ((i % 128) == 127)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync usleep(1000);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else if (!(i % 4))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync pthread_yield();
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync AssertReleaseMsg(i < 4096, ("iCur=%#x pThis=%p\n", iCur, pThis));
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync /* Check the magic to fend off races with RTSemEventDestroy. */
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync return VERR_SEM_DESTROYED;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VINF_SUCCESS;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncstatic int rtSemEventWait(RTSEMEVENT EventSem, unsigned cMillies, bool fAutoResume)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Validate input.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync struct RTSEMEVENTINTERNAL *pThis = EventSem;
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync AssertReturn(VALID_PTR(pThis) && pThis->iMagic == RTSEMEVENT_MAGIC,
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync VERR_INVALID_HANDLE);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Quickly check whether it's signaled.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync if (ASMAtomicCmpXchgS32(&pThis->cWaiters, 0, -1))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VINF_SUCCESS;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Convert timeout value.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync struct timespec ts;
f9e38e609bea9e849b27173024dc82d93bcbf5fcvboxsync struct timespec *pTimeout = NULL;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (cMillies != RT_INDEFINITE_WAIT)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync ts.tv_sec = cMillies / 1000;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync ts.tv_nsec = (cMillies % 1000) * 1000000;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync pTimeout = &ts;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * The wait loop.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync for (unsigned i = 0;; i++)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Announce that we're among the waiters.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync int32_t iNew = ASMAtomicIncS32(&pThis->cWaiters);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (iNew == 0)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VINF_SUCCESS;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (RT_LIKELY(iNew > 0))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Go to sleep.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync long rc = sys_futex(&pThis->cWaiters, FUTEX_WAIT, iNew, pTimeout, NULL, 0);
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VERR_SEM_DESTROYED;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /* Did somebody wake us up from RTSemEventSignal()? */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (rc == 0)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VINF_SUCCESS;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /* No, then the kernel woke us up or we failed going to sleep. Adjust the accounting. */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync iNew = ASMAtomicDecS32(&pThis->cWaiters);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync Assert(iNew >= 0);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /*
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Act on the wakup code.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (rc == -ETIMEDOUT)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync Assert(pTimeout);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VERR_TIMEOUT;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (rc == -EWOULDBLOCK)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /* retry with new value. */;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else if (rc == -EINTR)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync if (!fAutoResume)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VERR_INTERRUPTED;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /* this shouldn't happen! */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync AssertMsgFailed(("rc=%ld errno=%d\n", rc, errno));
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return RTErrConvertFromErrno(rc);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync else
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync {
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /* this can't happen. */
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return VERR_SEM_DESTROYED;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync AssertReleaseMsgFailed(("iNew=%d\n", iNew));
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync }
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventWait(RTSEMEVENT EventSem, unsigned cMillies)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync int rc = rtSemEventWait(EventSem, cMillies, true);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync Assert(rc != VERR_INTERRUPTED);
f9e38e609bea9e849b27173024dc82d93bcbf5fcvboxsync Assert(rc != VERR_TIMEOUT || cMillies != RT_INDEFINITE_WAIT);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return rc;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT EventSem, unsigned cMillies)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync{
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync return rtSemEventWait(EventSem, cMillies, false);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync}
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync#endif /* glibc < 2.6 */