/* $Id: semfastmutex-r0drv-linux.c 109033 2016-07-22 18:27:37Z bird $ */
/** @file
 * IPRT - Fast Mutex Semaphores, Ring-0 Driver, Linux.
 */

/*
 * Copyright (C) 2006-2016 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>
#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
# include <iprt/thread.h>
#endif

#include "internal/magics.h"

/*********************************************************************************************************************************
*   Structures and Typedefs                                                                                                      *
*********************************************************************************************************************************/
/**
 * Wrapper for the linux semaphore structure.
 */
typedef struct RTSEMFASTMUTEXINTERNAL {
    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
	uint32_t u32Magic;
    /** the linux semaphore. */
	struct semaphore Semaphore;
#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
    /** For check. */
	RTNATIVETHREAD volatile Owner;
#endif
} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;

RTDECL(int) RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
{
	IPRT_LINUX_SAVE_EFL_AC();

	/*
	 * Allocate.
	 */
	PRTSEMFASTMUTEXINTERNAL pThis;
	pThis = (PRTSEMFASTMUTEXINTERNAL) RTMemAlloc(sizeof(*pThis));
	if (!pThis)
		return VERR_NO_MEMORY;

	/*
	 * Initialize.
	 */
	pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
	sema_init(&pThis->Semaphore, 1);
#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
	pThis->Owner = NIL_RTNATIVETHREAD;
#endif

	*phFastMtx = pThis;
	IPRT_LINUX_RESTORE_EFL_AC();
	return VINF_SUCCESS;
}

RT_EXPORT_SYMBOL(RTSemFastMutexCreate);

RTDECL(int)RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
{
	/*
	 * Validate.
	 */
	PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
	if (pThis == NIL_RTSEMFASTMUTEX)
		return VINF_SUCCESS;
	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
	AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC,
			("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
			VERR_INVALID_HANDLE);

	ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
	RTMemFree(pThis);
	return VINF_SUCCESS;
}

RT_EXPORT_SYMBOL(RTSemFastMutexDestroy);

RTDECL(int)RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
{
	IPRT_LINUX_SAVE_EFL_AC();

	/*
	 * Validate.
	 */
	PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
	AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC,
			("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
			VERR_INVALID_HANDLE);

	IPRT_DEBUG_SEMS_STATE(pThis, 'd');
	down(&pThis->Semaphore);
#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
	IPRT_DEBUG_SEMS_STATE(pThis, 'o');
	AssertRelease(pThis->Owner == NIL_RTNATIVETHREAD);
	ASMAtomicUoWriteSize(&pThis->Owner, RTThreadNativeSelf());
#endif

	IPRT_LINUX_RESTORE_EFL_ONLY_AC();
	return VINF_SUCCESS;
}

RT_EXPORT_SYMBOL(RTSemFastMutexRequest);

RTDECL(int)RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
{
	IPRT_LINUX_SAVE_EFL_AC();

	/*
	 * Validate.
	 */
	PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
	AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC,
			("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
			VERR_INVALID_HANDLE);

#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
	AssertRelease(pThis->Owner == RTThreadNativeSelf());
	ASMAtomicUoWriteSize(&pThis->Owner, NIL_RTNATIVETHREAD);
#endif
	up(&pThis->Semaphore);
	IPRT_DEBUG_SEMS_STATE(pThis, 'u');

	IPRT_LINUX_RESTORE_EFL_ONLY_AC();
	return VINF_SUCCESS;
}

RT_EXPORT_SYMBOL(RTSemFastMutexRelease);
