source: vbox/trunk/src/VBox/Runtime/r0drv/linux/semevent-r0drv-linux.c@ 5228

/* $Id: semevent-r0drv-linux.c 5225 2007-10-10 15:06:48Z vboxsync $ */
/** @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 */);
}