semevent-linux.cpp revision 7ccd30dd4bbced565b32c255a11640cd4093abb6
5b281ba489ca18f0380d7efc7a5108b606cce449vboxsync * IPRT - Event Semaphore, Linux (2.6.x+).
1c94c0a63ba68be1a7b2c640e70d7a06464e4fcavboxsync * Copyright (C) 2006-2007 Sun Microsystems, Inc.
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 * 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 * 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 * 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.
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * glibc 2.6 fixed a serious bug in the mutex implementation. We wrote this
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync * linux specific event semaphores code in order to work around the bug. We
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync * will fall back on the pthread-based implementation if glibc is known to
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync * contain the bug fix.
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * The external refernce to epoll_pwait is a hack which prevents that we link
0a7b20727716a00270f358a1c546473d8c36e8f3vboxsync * against glibc < 2.6.
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsyncasm volatile (".global epoll_pwait");
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync#else /* glibc < 2.6 */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/*******************************************************************************
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync* Header Files *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync*******************************************************************************/
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync#if 0 /* With 2.6.17 futex.h has become C++ unfriendly. */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync/*******************************************************************************
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync* Structures and Typedefs *
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync*******************************************************************************/
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Linux (single wakup) event semaphore.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /** Magic value. */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync /** The futex state variable.
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync * 0 means not signalled.
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync * 1 means signalled */
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync /** The number of waiting threads */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Wrapper for the futex syscall.
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsyncstatic long sys_futex(uint32_t volatile *uaddr, int op, int val, struct timespec *utime, int32_t *uaddr2, int val3)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync long rc = syscall(__NR_futex, uaddr, op, val, utime, uaddr2, val3);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Allocate semaphore handle.
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync struct RTSEMEVENTINTERNAL *pThis = (struct RTSEMEVENTINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTINTERNAL));
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Validate input.
660fd430a3a8cfa16505d04c7c577acf89d45a40vboxsync AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Invalidate the semaphore and wake up anyone waiting on it.
cce6b7c4e45848f22615d68ba5865b71abbfac95vboxsync ASMAtomicXchgSize(&pThis->iMagic, RTSEMEVENT_MAGIC | UINT32_C(0x80000000));
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync if (ASMAtomicXchgS32(&pThis->cWaiters, INT32_MIN / 2) > 0)
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync sys_futex(&pThis->fSignalled, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Free the semaphore memory and be gone.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Validate input.
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync AssertReturn(VALID_PTR(pThis) && pThis->iMagic == RTSEMEVENT_MAGIC,
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync /* somebody is waiting, try wake up one of them. */
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync long cWoken = sys_futex(&pThis->fSignalled, FUTEX_WAKE, 1, NULL, NULL, 0);
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncstatic int rtSemEventWait(RTSEMEVENT EventSem, unsigned cMillies, bool fAutoResume)
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Validate input.
89dfdbb56cf9dddad3c7685b41bda1e4e4c1d6f9vboxsync AssertReturn(VALID_PTR(pThis) && pThis->iMagic == RTSEMEVENT_MAGIC,
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Quickly check whether it's signaled.
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * Convert timeout value.
7ccd30dd4bbced565b32c255a11640cd4093abb6vboxsync u64End = RTTimeSystemNanoTS() + cMillies * 1000000;
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsync * The wait loop.
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync long lrc = sys_futex(&pThis->fSignalled, FUTEX_WAIT, 0, pTimeout, NULL, 0);
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync /* successful wakeup or fSignalled > 0 in the meantime */
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync /* this shouldn't happen! */
65146b9eb3e96dbac286e55faa020bbfd74037d7vboxsync AssertMsgFailed(("rc=%ld errno=%d\n", lrc, errno));
7e10aea6606a51d35041e5a85f9e4f1bd19c4062vboxsync /* adjust the relative timeout */
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventWait(RTSEMEVENT EventSem, unsigned cMillies)
f9e38e609bea9e849b27173024dc82d93bcbf5fcvboxsync Assert(rc != VERR_TIMEOUT || cMillies != RT_INDEFINITE_WAIT);
9e5c26690d45216629b5f588aced8fcfb68c23b6vboxsyncRTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT EventSem, unsigned cMillies)
3aad980b92149dd95a1ab72ddb8d11d61a28ace6vboxsync#endif /* glibc < 2.6 */