diff options
Diffstat (limited to 'cpukit/score/include/rtems/score/smplockmcs.h')
| -rw-r--r-- | cpukit/score/include/rtems/score/smplockmcs.h | 262 |
1 files changed, 0 insertions, 262 deletions
diff --git a/cpukit/score/include/rtems/score/smplockmcs.h b/cpukit/score/include/rtems/score/smplockmcs.h deleted file mode 100644 index 5a1ad23dc9..0000000000 --- a/cpukit/score/include/rtems/score/smplockmcs.h +++ /dev/null @@ -1,262 +0,0 @@ -/** - * @file - * - * @ingroup ScoreSMPLock - * - * @brief SMP Lock API - */ - -/* - * Copyright (c) 2016 embedded brains GmbH - * - * The license and distribution terms for this file may be - * found in the file LICENSE in this distribution or at - * http://www.rtems.org/license/LICENSE. - */ - -#ifndef _RTEMS_SCORE_SMPLOCKMCS_H -#define _RTEMS_SCORE_SMPLOCKMCS_H - -#include <rtems/score/cpuopts.h> - -#if defined(RTEMS_SMP) - -#include <rtems/score/atomic.h> -#include <rtems/score/smplockstats.h> - -#ifdef __cplusplus -extern "C" { -#endif /* __cplusplus */ - -/** - * @addtogroup ScoreSMPLock - * - * @{ - */ - -/** - * @brief SMP Mellor-Crummey and Scott (MCS) lock context. - */ -typedef struct SMP_MCS_lock_Context { - /** - * @brief The next context on the queue if it exists. - */ - union { - /** - * @brief The next context as an atomic unsigned integer pointer value. - */ - Atomic_Uintptr atomic; - - /** - * @brief The next context as a normal pointer. - * - * Only provided for debugging purposes. - */ - struct SMP_MCS_lock_Context *normal; - } next; - - /** - * @brief Indicates if the lock is owned or free in case a previous context - * exits on the queue. - * - * This field is initialized to a non-zero value. The previous lock owner - * (which is the owner of the previous context) will set it to zero during - * its lock release. - */ - Atomic_Uint locked; - -#if defined(RTEMS_PROFILING) - SMP_lock_Stats_context Stats_context; - - unsigned int queue_length; -#endif -} SMP_MCS_lock_Context; - -/** - * @brief SMP Mellor-Crummey and Scott (MCS) lock control. - */ -typedef struct { - /** - * @brief The queue tail context. - * - * The lock is free, in case this field is zero, otherwise it is locked by - * the owner of the queue head. - */ - union { - /** - * @brief The queue tail context as an atomic unsigned integer pointer - * value. - */ - Atomic_Uintptr atomic; - - /** - * @brief The queue tail context as a normal pointer. - * - * Only provided for debugging purposes. - */ - struct SMP_MCS_lock_Context *normal; - } queue; -} SMP_MCS_lock_Control; - -/** - * @brief SMP MCS lock control initializer for static initialization. - */ -#define SMP_MCS_LOCK_INITIALIZER { { ATOMIC_INITIALIZER_UINTPTR( 0 ) } } - -/** - * @brief Initializes an SMP MCS lock. - * - * Concurrent initialization leads to unpredictable results. - * - * @param lock The SMP MCS lock control. - */ -static inline void _SMP_MCS_lock_Initialize( SMP_MCS_lock_Control *lock ) -{ - _Atomic_Init_uintptr( &lock->queue.atomic, 0 ); -} - -/** - * @brief Destroys an SMP MCS lock. - * - * Concurrent destruction leads to unpredictable results. - * - * @param lock The SMP MCS lock control. - */ -static inline void _SMP_MCS_lock_Destroy( SMP_MCS_lock_Control *lock ) -{ - (void) lock; -} - -static inline void _SMP_MCS_lock_Do_acquire( - SMP_MCS_lock_Control *lock, - SMP_MCS_lock_Context *context -#if defined(RTEMS_PROFILING) - , - SMP_lock_Stats *stats -#endif -) -{ - SMP_MCS_lock_Context *previous; -#if defined(RTEMS_PROFILING) - SMP_lock_Stats_acquire_context acquire_context; - - _SMP_lock_Stats_acquire_begin( &acquire_context ); - context->queue_length = 0; -#endif - - _Atomic_Store_uintptr( &context->next.atomic, 0, ATOMIC_ORDER_RELAXED ); - _Atomic_Store_uint( &context->locked, 1, ATOMIC_ORDER_RELAXED ); - - previous = (SMP_MCS_lock_Context *) _Atomic_Exchange_uintptr( - &lock->queue.atomic, - (uintptr_t) context, - ATOMIC_ORDER_ACQ_REL - ); - - if ( previous != NULL ) { - unsigned int locked; - - _Atomic_Store_uintptr( - &previous->next.atomic, - (uintptr_t) context, - ATOMIC_ORDER_RELAXED - ); - - do { - locked = _Atomic_Load_uint( &context->locked, ATOMIC_ORDER_ACQUIRE ); - } while ( locked != 0 ); - } - -#if defined(RTEMS_PROFILING) - _SMP_lock_Stats_acquire_end( - &acquire_context, - stats, - &context->Stats_context, - context->queue_length - ); -#endif -} - -/** - * @brief Acquires an SMP MCS lock. - * - * This function will not disable interrupts. The caller must ensure that the - * current thread of execution is not interrupted indefinite once it obtained - * the SMP MCS lock. - * - * @param lock The SMP MCS lock control. - * @param context The SMP MCS lock context. - * @param stats The SMP lock statistics. - */ -#if defined(RTEMS_PROFILING) - #define _SMP_MCS_lock_Acquire( lock, context, stats ) \ - _SMP_MCS_lock_Do_acquire( lock, context, stats ) -#else - #define _SMP_MCS_lock_Acquire( lock, context, stats ) \ - _SMP_MCS_lock_Do_acquire( lock, context ) -#endif - -/** - * @brief Releases an SMP MCS lock. - * - * @param lock The SMP MCS lock control. - * @param context The SMP MCS lock context. - */ -static inline void _SMP_MCS_lock_Release( - SMP_MCS_lock_Control *lock, - SMP_MCS_lock_Context *context -) -{ - SMP_MCS_lock_Context *next; - - next = (SMP_MCS_lock_Context *) _Atomic_Load_uintptr( - &context->next.atomic, - ATOMIC_ORDER_RELAXED - ); - - if ( next == NULL ) { - uintptr_t expected; - bool success; - - expected = (uintptr_t) context; - success = _Atomic_Compare_exchange_uintptr( - &lock->queue.atomic, - &expected, - 0, - ATOMIC_ORDER_RELEASE, - ATOMIC_ORDER_RELAXED - ); - - if ( success ) { -#if defined(RTEMS_PROFILING) - _SMP_lock_Stats_release_update( &context->Stats_context ); -#endif - /* Nobody waits. So, we are done */ - return; - } - - do { - next = (SMP_MCS_lock_Context *) _Atomic_Load_uintptr( - &context->next.atomic, - ATOMIC_ORDER_RELAXED - ); - } while ( next == NULL ); - } - -#if defined(RTEMS_PROFILING) - next->queue_length = context->queue_length + 1; - _SMP_lock_Stats_release_update( &context->Stats_context ); -#endif - - _Atomic_Store_uint( &next->locked, 0, ATOMIC_ORDER_RELEASE ); -} - -/**@}*/ - -#ifdef __cplusplus -} -#endif /* __cplusplus */ - -#endif /* RTEMS_SMP */ - -#endif /* _RTEMS_SCORE_SMPLOCKMCS_H */ |