/* $Id: spinlock-r0drv-linux.c 109135 2016-07-26 15:16:41Z bird $ */
/** @file
 * IPRT - Spinlocks, 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/spinlock.h>

#include <iprt/asm.h>
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
# include <iprt/asm-amd64-x86.h>
#endif
#include <iprt/assert.h>
#include <iprt/err.h>
#include <iprt/mem.h>
#include <iprt/mp.h>
#include <iprt/thread.h>
#include "internal/magics.h"

/*********************************************************************************************************************************
*   Structures and Typedefs                                                                                                      *
*********************************************************************************************************************************/
/**
 * Wrapper for the spinlock_t structure.
 */
typedef struct RTSPINLOCKINTERNAL {
    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
	uint32_t volatile u32Magic;
    /** The spinlock creation flags.  */
	uint32_t fFlags;
    /** The saved interrupt flag. */
	unsigned long volatile fIntSaved;
    /** The linux spinlock structure. */
	spinlock_t Spinlock;
#ifdef RT_MORE_STRICT
    /** The idAssertCpu variable before acquring the lock for asserting after
     *  releasing the spinlock. */
	RTCPUID volatile idAssertCpu;
    /** The CPU that owns the lock. */
	RTCPUID volatile idCpuOwner;
#endif
} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;

RTDECL(int) RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags,
			     const char *pszName)
{
	IPRT_LINUX_SAVE_EFL_AC();
	PRTSPINLOCKINTERNAL pThis;
	AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE
		     || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE,
		     VERR_INVALID_PARAMETER);
	RT_NOREF_PV(pszName);

	/*
	 * Allocate.
	 */
	Assert(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
	pThis = (PRTSPINLOCKINTERNAL) RTMemAlloc(sizeof(*pThis));
	if (!pThis)
		return VERR_NO_MEMORY;
	/*
	 * Initialize and return.
	 */
	pThis->u32Magic = RTSPINLOCK_MAGIC;
	pThis->fFlags = fFlags;
	pThis->fIntSaved = 0;
#ifdef RT_MORE_STRICT
	pThis->idCpuOwner = NIL_RTCPUID;
	pThis->idAssertCpu = NIL_RTCPUID;
#endif

	spin_lock_init(&pThis->Spinlock);

	*pSpinlock = pThis;
	IPRT_LINUX_RESTORE_EFL_AC();
	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_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;
	IPRT_LINUX_SAVE_EFL_AC();
	RT_ASSERT_PREEMPT_CPUID_VAR();
	AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
		  ("pThis=%p u32Magic=%08x\n", pThis,
		   pThis ? (int)pThis->u32Magic : 0));

#ifdef CONFIG_PROVE_LOCKING
	lockdep_off();
#endif
	if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE) {
		unsigned long fIntSaved;
		spin_lock_irqsave(&pThis->Spinlock, fIntSaved);
		pThis->fIntSaved = fIntSaved;
	} else
		spin_lock(&pThis->Spinlock);
#ifdef CONFIG_PROVE_LOCKING
	lockdep_on();
#endif

	IPRT_LINUX_RESTORE_EFL_ONLY_AC();
	RT_ASSERT_PREEMPT_CPUID_SPIN_ACQUIRED(pThis);
}

RT_EXPORT_SYMBOL(RTSpinlockAcquire);

RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
{
	PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL) Spinlock;
	IPRT_LINUX_SAVE_EFL_AC();	/* spin_unlock* may preempt and trash eflags.ac. */
	RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE_VARS();
	AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
		  ("pThis=%p u32Magic=%08x\n", pThis,
		   pThis ? (int)pThis->u32Magic : 0));
	RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE(pThis);

#ifdef CONFIG_PROVE_LOCKING
	lockdep_off();
#endif
	if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE) {
		unsigned long fIntSaved = pThis->fIntSaved;
		pThis->fIntSaved = 0;
		spin_unlock_irqrestore(&pThis->Spinlock, fIntSaved);
	} else
		spin_unlock(&pThis->Spinlock);
#ifdef CONFIG_PROVE_LOCKING
	lockdep_on();
#endif

	IPRT_LINUX_RESTORE_EFL_ONLY_AC();
	RT_ASSERT_PREEMPT_CPUID();
}

RT_EXPORT_SYMBOL(RTSpinlockRelease);
