resourcemgr/criticalsection_linux.c

//**********************************************************************;
// Copyright (c) 2015, Intel Corporation
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice,
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// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
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#include <stdio.h>
#include <sapi/tpm20.h>

#include "criticalsection.h"
#include "debug.h"

#if __linux || __unix

//
// This function starts a critical section, e.g. some code that must
// not be interfered with.
//
// Currently this is used to grant a single connection exclusive
// access to the TPM.  But it could be used for other critical sections
// as well.
//
TSS2_RC StartCriticalSection( TPM_MUTEX *tpmMutex, char *dbgString )
{
	TSS2_RC rval = TSS2_RC_SUCCESS;
#ifdef DEBUG_MUTEX
	UINT8 mutexAcquired = 0;
#endif
	int mutexWaitRetVal;
	struct timespec semWait = { 0, 0 };

	// Critical section starts here--take the mutex.
	clock_gettime( CLOCK_REALTIME, &semWait );
	semWait.tv_sec += MILLISECOND_WAIT / 1000;

	mutexWaitRetVal = sem_timedwait( tpmMutex, &semWait );
	if( mutexWaitRetVal != 0 )
	{
		rval = TSS2_TCTI_RC_TRY_AGAIN;
	}

#ifdef DEBUG_MUTEX
    else
	{
		mutexAcquired = 1;
	}

	if( mutexAcquired )
	{
		DebugPrintf(NO_PREFIX, "In %s, acquired mutex\n", dbgString );
	}
	else
	{
		DebugPrintf(NO_PREFIX, "In %s, failed to release mutex error: %d\n", errno, dbgString );
	}
#endif

	return rval;
}

TSS2_RC EndCriticalSection( TPM_MUTEX *tpmMutex, char *dbgString )
{
	TSS2_RC rval = TSS2_RC_SUCCESS;
#ifdef DEBUG_MUTEX
	UINT8 mutexReleased = 0;
#endif

	if( 0 != sem_post( tpmMutex ) )
	{
		rval = TSS2_TCTI_RC_TRY_AGAIN;
	}

#ifdef DEBUG_MUTEX
	else
	{
	   mutexReleased = 1;
	}

	if( mutexReleased )
	{
		DebugPrintf(NO_PREFIX, "In PlatformCommand, released mutex\n" );
	}
	else
	{
		DebugPrintf(NO_PREFIX, "In PlatformCommand, failed to release mutex error: %d\n", errno );
	}
#endif

	return rval;
}

#endif