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/* $Id: spinlock-generic.cpp $ */
/** @file
* IPRT - Spinlock, generic implementation.
*/
/*
* Copyright (C) 2006-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program 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 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox 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.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/*********************************************************************************************************************************
* Defined Constants And Macros *
*********************************************************************************************************************************/
/** @def RT_CFG_SPINLOCK_GENERIC_DO_SLEEP
* Force cpu yields after spinning the number of times indicated by the define.
* If 0 we will spin forever. */
#define RT_CFG_SPINLOCK_GENERIC_DO_SLEEP 100000
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include <iprt/spinlock.h>
#include "internal/iprt.h"
#include <iprt/alloc.h>
#include <iprt/asm.h>
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
# include <iprt/asm-amd64-x86.h>
#endif
#include <iprt/errcore.h>
#include <iprt/assert.h>
#if RT_CFG_SPINLOCK_GENERIC_DO_SLEEP
# include <iprt/thread.h>
#endif
#include "internal/magics.h"
/*********************************************************************************************************************************
* Structures and Typedefs *
*********************************************************************************************************************************/
/**
* Generic spinlock structure.
*/
typedef struct RTSPINLOCKINTERNAL
{
/** Spinlock magic value (RTSPINLOCK_GEN_MAGIC). */
uint32_t u32Magic;
/** The spinlock creation flags. */
uint32_t fFlags;
/** The spinlock. */
uint32_t volatile fLocked;
/** The saved CPU interrupt. */
uint32_t volatile fIntSaved;
} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
RTDECL(int) RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
{
PRTSPINLOCKINTERNAL pThis;
AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
RT_NOREF_PV(pszName);
/*
* Allocate.
*/
pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
if (!pThis)
return VERR_NO_MEMORY;
/*
* Initialize and return.
*/
pThis->u32Magic = RTSPINLOCK_GEN_MAGIC;
pThis->fFlags = fFlags;
pThis->fIntSaved = 0;
ASMAtomicWriteU32(&pThis->fLocked, 0);
*pSpinlock = pThis;
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSpinlockCreate);
RTDECL(int) RTSpinlockDestroy(RTSPINLOCK Spinlock)
{
/*
* Validate input.
*/
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
if (!pThis)
return VERR_INVALID_PARAMETER;
if (pThis->u32Magic != RTSPINLOCK_GEN_MAGIC)
{
AssertMsgFailed(("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic));
return VERR_INVALID_PARAMETER;
}
ASMAtomicIncU32(&pThis->u32Magic);
RTMemFree(pThis);
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSpinlockDestroy);
RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
{
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_GEN_MAGIC,
("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
{
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
uint32_t fIntSaved = ASMGetFlags();
#endif
#if RT_CFG_SPINLOCK_GENERIC_DO_SLEEP
for (;;)
{
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
ASMIntDisable();
#endif
for (int c = RT_CFG_SPINLOCK_GENERIC_DO_SLEEP; c > 0; c--)
{
if (ASMAtomicCmpXchgU32(&pThis->fLocked, 1, 0))
{
# if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
pThis->fIntSaved = fIntSaved;
# endif
return;
}
ASMNopPause();
}
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
ASMSetFlags(fIntSaved);
#endif
RTThreadYield();
}
#else
for (;;)
{
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
ASMIntDisable();
#endif
if (ASMAtomicCmpXchgU32(&pThis->fLocked, 1, 0))
{
# if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
pThis->fIntSaved = fIntSaved;
# endif
return;
}
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
ASMSetFlags(fIntSaved);
#endif
ASMNopPause();
}
#endif
}
else
{
#if RT_CFG_SPINLOCK_GENERIC_DO_SLEEP
for (;;)
{
for (int c = RT_CFG_SPINLOCK_GENERIC_DO_SLEEP; c > 0; c--)
{
if (ASMAtomicCmpXchgU32(&pThis->fLocked, 1, 0))
return;
ASMNopPause();
}
RTThreadYield();
}
#else
while (!ASMAtomicCmpXchgU32(&pThis->fLocked, 1, 0))
ASMNopPause();
#endif
}
}
RT_EXPORT_SYMBOL(RTSpinlockAcquire);
RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
{
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_GEN_MAGIC,
("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
{
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
uint32_t fIntSaved = pThis->fIntSaved;
pThis->fIntSaved = 0;
#endif
if (!ASMAtomicCmpXchgU32(&pThis->fLocked, 0, 1))
AssertMsgFailed(("Spinlock %p was not locked!\n", pThis));
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
ASMSetFlags(fIntSaved);
#endif
}
else
{
if (!ASMAtomicCmpXchgU32(&pThis->fLocked, 0, 1))
AssertMsgFailed(("Spinlock %p was not locked!\n", pThis));
}
}
RT_EXPORT_SYMBOL(RTSpinlockRelease);
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