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/* $Id: semevent-r0drv-linux.c 29648 2010-05-18 16:15:42Z vboxsync $ */
/** @file
* IPRT - Single Release Event Semaphores, Ring-0 Driver, Linux.
*/
/*
* Copyright (C) 2006-2007 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.
*/
/*******************************************************************************
* Header Files *
*******************************************************************************/
#include "the-linux-kernel.h"
#include "internal/iprt.h"
#include <iprt/semaphore.h>
#include <iprt/alloc.h>
#include <iprt/assert.h>
#include <iprt/asm.h>
#include <iprt/err.h>
#include "internal/magics.h"
/*******************************************************************************
* Structures and Typedefs *
*******************************************************************************/
/**
* Linux event semaphore.
*/
typedef struct RTSEMEVENTINTERNAL
{
/** Magic value (RTSEMEVENT_MAGIC). */
uint32_t volatile u32Magic;
/** The object status - !0 when signaled and 0 when reset. */
uint32_t volatile fState;
/** The wait queue. */
wait_queue_head_t Head;
} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
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, ...)
{
PRTSEMEVENTINTERNAL pThis;
AssertReturn(!(fFlags & ~RTSEMEVENT_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
pThis = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pThis));
if (!pThis)
return VERR_NO_MEMORY;
pThis->u32Magic = RTSEMEVENT_MAGIC;
pThis->fState = 0;
init_waitqueue_head(&pThis->Head);
*phEventSem = pThis;
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSemEventCreate);
RTDECL(int) RTSemEventDestroy(RTSEMEVENT hEventSem)
{
/*
* Validate input.
*/
PRTSEMEVENTINTERNAL pThis = hEventSem;
if (pThis == NIL_RTSEMEVENT)
return VINF_SUCCESS;
AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
/*
* Invalidate it and signal the object just in case.
*/
ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC);
ASMAtomicWriteU32(&pThis->fState, 0);
Assert(!waitqueue_active(&pThis->Head));
wake_up_all(&pThis->Head);
RTMemFree(pThis);
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSemEventDestroy);
RTDECL(int) RTSemEventSignal(RTSEMEVENT hEventSem)
{
/*
* Validate input.
*/
PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
/*
* Signal the event object.
*/
ASMAtomicWriteU32(&pThis->fState, 1);
wake_up(&pThis->Head);
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSemEventSignal);
/**
* Worker for RTSemEvent and RTSemEventNoResume.
*
* @returns VBox status code.
* @param pThis The event semaphore.
* @param cMillies The number of milliseconds to wait.
* @param fInterruptible Whether it's an interruptible wait or not.
*/
static int rtSemEventWait(PRTSEMEVENTINTERNAL pThis, RTMSINTERVAL cMillies, bool fInterruptible)
{
/*
* Ok wait for it.
*/
DEFINE_WAIT(Wait);
int rc = VINF_SUCCESS;
long lTimeout = cMillies == RT_INDEFINITE_WAIT ? MAX_SCHEDULE_TIMEOUT : msecs_to_jiffies(cMillies);
#ifdef IPRT_DEBUG_SEMS
snprintf(current->comm, sizeof(current->comm), "e%lx", IPRT_DEBUG_SEMS_ADDRESS(pThis));
#endif
for (;;)
{
/* make everything thru schedule_timeout() atomic scheduling wise. */
prepare_to_wait(&pThis->Head, &Wait, fInterruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
/* check the condition. */
if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
break;
/* check for pending signals. */
if (fInterruptible && signal_pending(current))
{
rc = VERR_INTERRUPTED;
break;
}
/* wait */
lTimeout = schedule_timeout(lTimeout);
after_wait(&Wait);
/* Check if someone destroyed the semaphore while we were waiting. */
if (pThis->u32Magic != RTSEMEVENT_MAGIC)
{
rc = VERR_SEM_DESTROYED;
break;
}
/* check for timeout. */
if (!lTimeout)
{
rc = VERR_TIMEOUT;
break;
}
}
finish_wait(&pThis->Head, &Wait);
#ifdef IPRT_DEBUG_SEMS
snprintf(current->comm, sizeof(current->comm), "e%lx:%d", IPRT_DEBUG_SEMS_ADDRESS(pThis), rc);
#endif
return rc;
}
RTDECL(int) RTSemEventWait(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies)
{
PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
return VINF_SUCCESS;
return rtSemEventWait(pThis, cMillies, false /* fInterruptible */);
}
RT_EXPORT_SYMBOL(RTSemEventWait);
RTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies)
{
PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
return VINF_SUCCESS;
return rtSemEventWait(pThis, cMillies, true /* fInterruptible */);
}
RT_EXPORT_SYMBOL(RTSemEventWaitNoResume);
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