semevent-r0drv-linux.c revision a8e0cb7ddfd05bcabf5e18959cf09e723f254663
/* $Id$ */
/** @file
* innotek Portable Runtime - Single Release Event Semaphores, Ring-0 Driver, Linux.
*/
/*
* Copyright (C) 2006-2007 innotek GmbH
*
* 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 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.
*/
/*******************************************************************************
* Header Files *
*******************************************************************************/
#include "the-linux-kernel.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 pEventSem)
{
PRTSEMEVENTINTERNAL pEventInt = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pEventInt));
if (pEventInt)
{
pEventInt->u32Magic = RTSEMEVENT_MAGIC;
init_waitqueue_head(&pEventInt->Head);
*pEventSem = pEventInt;
return VINF_SUCCESS;
}
return VERR_NO_MEMORY;
}
RTDECL(int) RTSemEventDestroy(RTSEMEVENT EventSem)
{
/*
* Validate input.
*/
PRTSEMEVENTINTERNAL pEventInt = (PRTSEMEVENTINTERNAL)EventSem;
if (!pEventInt)
return VERR_INVALID_PARAMETER;
if (pEventInt->u32Magic != RTSEMEVENT_MAGIC)
{
AssertMsgFailed(("pEventInt->u32Magic=%RX32 pEventInt=%p\n", pEventInt->u32Magic, pEventInt));
return VERR_INVALID_PARAMETER;
}
/*
* Invalidate it and signal the object just in case.
*/
ASMAtomicIncU32(&pEventInt->u32Magic);
ASMAtomicXchgU32(&pEventInt->fState, 0);
Assert(!waitqueue_active(&pEventInt->Head));
wake_up_all(&pEventInt->Head);
RTMemFree(pEventInt);
return VINF_SUCCESS;
}
RTDECL(int) RTSemEventSignal(RTSEMEVENT EventSem)
{
/*
* Validate input.
*/
PRTSEMEVENTINTERNAL pEventInt = (PRTSEMEVENTINTERNAL)EventSem;
if (!pEventInt)
return VERR_INVALID_PARAMETER;
if ( !pEventInt
|| pEventInt->u32Magic != RTSEMEVENT_MAGIC)
{
AssertMsgFailed(("pEventInt->u32Magic=%RX32 pEventInt=%p\n", pEventInt ? pEventInt->u32Magic : 0, pEventInt));
return VERR_INVALID_PARAMETER;
}
/*
* Signal the event object.
*/
ASMAtomicXchgU32(&pEventInt->fState, 1);
wake_up(&pEventInt->Head);
return VINF_SUCCESS;
}
/**
* Worker for RTSemEvent and RTSemEventNoResume.
*
* @returns VBox status code.
* @param pEventInt 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 pEventInt, unsigned 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);
for (;;)
{
/* make everything thru schedule() atomic scheduling wise. */
prepare_to_wait(&pEventInt->Head, &Wait, fInterruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
/* check the condition. */
if (ASMAtomicCmpXchgU32(&pEventInt->fState, 0, 1))
break;
/* check for pending signals. */
if (fInterruptible && signal_pending(current))
{
rc = VERR_INTERRUPTED;
break;
}
/* wait */
lTimeout = schedule_timeout(lTimeout);
/* Check if someone destroyed the semaphore while we were waiting. */
if (pEventInt->u32Magic != RTSEMEVENT_MAGIC)
{
rc = VERR_SEM_DESTROYED;
break;
}
/* check for timeout. */
if (!lTimeout)
{
rc = VERR_TIMEOUT;
break;
}
}
finish_wait(&pEventInt->Head, &Wait);
return rc;
}
RTDECL(int) RTSemEventWait(RTSEMEVENT EventSem, unsigned cMillies)
{
PRTSEMEVENTINTERNAL pEventInt = (PRTSEMEVENTINTERNAL)EventSem;
if (!pEventInt)
return VERR_INVALID_PARAMETER;
if ( !pEventInt
|| pEventInt->u32Magic != RTSEMEVENT_MAGIC)
{
AssertMsgFailed(("pEventInt->u32Magic=%RX32 pEventInt=%p\n", pEventInt ? pEventInt->u32Magic : 0, pEventInt));
return VERR_INVALID_PARAMETER;
}
if (ASMAtomicCmpXchgU32(&pEventInt->fState, 0, 1))
return VINF_SUCCESS;
return rtSemEventWait(pEventInt, cMillies, false /* fInterruptible */);
}
RTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT EventSem, unsigned cMillies)
{
PRTSEMEVENTINTERNAL pEventInt = (PRTSEMEVENTINTERNAL)EventSem;
if (!pEventInt)
return VERR_INVALID_PARAMETER;
if ( !pEventInt
|| pEventInt->u32Magic != RTSEMEVENT_MAGIC)
{
AssertMsgFailed(("pEventInt->u32Magic=%RX32 pEventInt=%p\n", pEventInt ? pEventInt->u32Magic : 0, pEventInt));
return VERR_INVALID_PARAMETER;
}
if (ASMAtomicCmpXchgU32(&pEventInt->fState, 0, 1))
return VINF_SUCCESS;
return rtSemEventWait(pEventInt, cMillies, true /* fInterruptible */);
}