鸿蒙轻内核A核源码分析系列八—信号量Semaphore

typedef struct {
    UINT8 semStat; /**< 信号量状态 */
    UINT16 semCount; /**< 可用的信号量数量 */
    UINT16 maxSemCount;  /**< 可用的信号量最大数量 */
    UINT32 semID; /**< 信号量Id */
    LOS_DL_LIST semList; /**< 阻塞在该信号量的任务链表 */
} LosSemCB;

⑴    #define OS_SEM_UNUSED               0
⑵    #define OS_SEM_USED                 1
⑶    #define GET_SEM_LIST(ptr) LOS_DL_LIST_ENTRY(ptr, LosSemCB, semList)
⑷    #define GET_SEM(semid) (((LosSemCB *)g_allSem) + (semid))
    /**
     * @ingroup los_sem
     * COUNT | INDEX  split bit
     */
⑸  #define SEM_SPLIT_BIT        16
    /**
     * @ingroup los_sem
     * Set the semaphore id
     */
⑹  #define SET_SEM_ID(count, semID)    (((count) << SEM_SPLIT_BIT) | (semID))
    /**
     * @ingroup los_sem
     * get the semaphore index
     */
⑺  #define GET_SEM_INDEX(semID)        ((semID) & ((1U << SEM_SPLIT_BIT) - 1))
    /**
     * @ingroup los_sem
     * get the semaphore count
     */
⑻   #define GET_SEM_COUNT(semID)        ((semID) >> SEM_SPLIT_BIT)
......

LITE_OS_SEC_TEXT_INIT UINT32 OsSemInit(VOID)
{
    LosSemCB *semNode = NULL;
    UINT32 index;
⑴  LOS_ListInit(&g_unusedSemList);
    /* system resident memory, don't free */
⑵  g_allSem = (LosSemCB *)LOS_MemAlloc(m_aucSysMem0, (LOSCFG_BASE_IPC_SEM_LIMIT * sizeof(LosSemCB)));
    if (g_allSem == NULL) {
        return LOS_ERRNO_SEM_NO_MEMORY;
    }
⑶  for (index = 0; index < LOSCFG_BASE_IPC_SEM_LIMIT; index++) {
        semNode = ((LosSemCB *)g_allSem) + index;
        semNode->semID = SET_SEM_ID(0, index);
        semNode->semStat = OS_SEM_UNUSED;
⑷      LOS_ListTailInsert(&g_unusedSemList, &semNode->semList);
    }
    if (OsSemDbgInitHook() != LOS_OK) {
        return LOS_ERRNO_SEM_NO_MEMORY;
    }
    return LOS_OK;
}

LITE_OS_SEC_TEXT_INIT UINT32 LOS_SemCreate(UINT16 count, UINT32 *semHandle)
{
    return OsSemCreate(count, OS_SEM_COUNT_MAX, semHandle);
}
LITE_OS_SEC_TEXT_INIT UINT32 LOS_BinarySemCreate(UINT16 count, UINT32 *semHandle)
{
    return OsSemCreate(count, OS_SEM_BINARY_COUNT_MAX, semHandle);
}

LITE_OS_SEC_TEXT_INIT UINT32 OsSemCreate(UINT16 count, UINT16 maxCount, UINT32 *semHandle)
{
    UINT32 intSave;
    LosSemCB *semCreated = NULL;
    LOS_DL_LIST *unusedSem = NULL;
    UINT32 errNo;
    UINT32 errLine;
    if (semHandle == NULL) {
        return LOS_ERRNO_SEM_PTR_NULL;
    }
    if (count > maxCount) {
        OS_GOTO_ERR_HANDLER(LOS_ERRNO_SEM_OVERFLOW);
    }
    SCHEDULER_LOCK(intSave);

⑴  if (LOS_ListEmpty(&g_unusedSemList)) {
        SCHEDULER_UNLOCK(intSave);
        OsSemInfoGetFullDataHook();
        OS_GOTO_ERR_HANDLER(LOS_ERRNO_SEM_ALL_BUSY);
    }
⑵  unusedSem = LOS_DL_LIST_FIRST(&g_unusedSemList);
    LOS_ListDelete(unusedSem);
    SCHEDULER_UNLOCK(intSave);
    semCreated = GET_SEM_LIST(unusedSem);
    semCreated->semCount = count;
    semCreated->semStat = OS_SEM_USED;
    semCreated->maxSemCount = maxCount;
⑶  LOS_ListInit(&semCreated->semList);
⑷  *semHandle = semCreated->semID;
    OsHookCall(LOS_HOOK_TYPE_SEM_CREATE, semCreated);
    OsSemDbgUpdateHook(semCreated->semID, OsCurrTaskGet()->taskEntry, count);
    return LOS_OK;
ERR_HANDLER:
    OS_RETURN_ERROR_P2(errLine, errNo);
}

LITE_OS_SEC_TEXT_INIT UINT32 LOS_SemDelete(UINT32 semHandle)
{
    UINT32 intSave;
    LosSemCB *semDeleted = NULL;
    UINT32 errNo;
    UINT32 errLine;
⑴  if (GET_SEM_INDEX(semHandle) >= (UINT32)LOSCFG_BASE_IPC_SEM_LIMIT) {
        OS_GOTO_ERR_HANDLER(LOS_ERRNO_SEM_INVALID);
    }
    semDeleted = GET_SEM(semHandle);
    SCHEDULER_LOCK(intSave);
⑵  if ((semDeleted->semStat == OS_SEM_UNUSED) || (semDeleted->semID != semHandle)) {
        SCHEDULER_UNLOCK(intSave);
        OS_GOTO_ERR_HANDLER(LOS_ERRNO_SEM_INVALID);
    }
⑶  if (!LOS_ListEmpty(&semDeleted->semList)) {
        SCHEDULER_UNLOCK(intSave);
        OS_GOTO_ERR_HANDLER(LOS_ERRNO_SEM_PENDED);
    }
⑷  LOS_ListTailInsert(&g_unusedSemList, &semDeleted->semList);
    semDeleted->semStat = OS_SEM_UNUSED;
    semDeleted->semID = SET_SEM_ID(GET_SEM_COUNT(semDeleted->semID) + 1, GET_SEM_INDEX(semDeleted->semID));
    OsHookCall(LOS_HOOK_TYPE_SEM_DELETE, semDeleted);
    OsSemDbgUpdateHook(semDeleted->semID, NULL, 0);
    SCHEDULER_UNLOCK(intSave);
    return LOS_OK;
ERR_HANDLER:
    OS_RETURN_ERROR_P2(errLine, errNo);
}

LITE_OS_SEC_TEXT UINT32 LOS_SemPend(UINT32 semHandle, UINT32 timeout)
{
    UINT32 intSave;
    LosSemCB *semPended = GET_SEM(semHandle);
    UINT32 retErr = LOS_OK;
    LosTaskCB *runTask = NULL;
⑴  if (GET_SEM_INDEX(semHandle) >= (UINT32)LOSCFG_BASE_IPC_SEM_LIMIT) {
        OS_RETURN_ERROR(LOS_ERRNO_SEM_INVALID);
    }
⑵  if (OS_INT_ACTIVE) {
        PRINT_ERR("!!!LOS_ERRNO_SEM_PEND_INTERR!!!\n");
        OsBackTrace();
        return LOS_ERRNO_SEM_PEND_INTERR;
    }
⑶  runTask = OsCurrTaskGet();
    if (runTask->taskStatus & OS_TASK_FLAG_SYSTEM_TASK) {
        OsBackTrace();
        return LOS_ERRNO_SEM_PEND_IN_SYSTEM_TASK;
    }
    SCHEDULER_LOCK(intSave);
⑷  if ((semPended->semStat == OS_SEM_UNUSED) || (semPended->semID != semHandle)) {
        retErr = LOS_ERRNO_SEM_INVALID;
        goto OUT;
    }
    /* Update the operate time, no matter the actual Pend success or not */
    OsSemDbgTimeUpdateHook(semHandle);
⑸  if (semPended->semCount > 0) {
        semPended->semCount--;
        OsHookCall(LOS_HOOK_TYPE_SEM_PEND, semPended, runTask, timeout);
        goto OUT;
⑹  } else if (!timeout) {
        retErr = LOS_ERRNO_SEM_UNAVAILABLE;
        goto OUT;
    }
⑺  if (!OsPreemptableInSched()) {
        PRINT_ERR("!!!LOS_ERRNO_SEM_PEND_IN_LOCK!!!\n");
        OsBackTrace();
        retErr = LOS_ERRNO_SEM_PEND_IN_LOCK;
        goto OUT;
    }
    OsHookCall(LOS_HOOK_TYPE_SEM_PEND, semPended, runTask, timeout);
⑻  OsTaskWaitSetPendMask(OS_TASK_WAIT_SEM, semPended->semID, timeout);
    retErr = runTask->ops->wait(runTask, &semPended->semList, timeout);
⑼  if (retErr == LOS_ERRNO_TSK_TIMEOUT) {
        retErr = LOS_ERRNO_SEM_TIMEOUT;
    }
OUT:
    SCHEDULER_UNLOCK(intSave);
    return retErr;
}

LITE_OS_SEC_TEXT UINT32 LOS_SemPost(UINT32 semHandle)
{
    UINT32 intSave;
    LosSemCB *semPosted = GET_SEM(semHandle);
    LosTaskCB *resumedTask = NULL;
    if (semHandle >= LOSCFG_BASE_IPC_SEM_LIMIT) {
        return LOS_ERRNO_SEM_INVALID;
    }
    intSave = LOS_IntLock();
    if (semPosted->semStat == OS_SEM_UNUSED) {
        LOS_IntRestore(intSave);
        OS_RETURN_ERROR(LOS_ERRNO_SEM_INVALID);
    }
⑴  if (semPosted->maxSemCount == semPosted->semCount) {
        LOS_IntRestore(intSave);
        OS_RETURN_ERROR(LOS_ERRNO_SEM_OVERFLOW);
    }
⑵  if (!LOS_ListEmpty(&semPosted->semList)) {
⑶      resumedTask = OS_TCB_FROM_PENDLIST(LOS_DL_LIST_FIRST(&(semPosted->semList)));
        resumedTask->taskSem = NULL;
⑷      OsSchedTaskWake(resumedTask);

        LOS_IntRestore(intSave);
        OsHookCall(LOS_HOOK_TYPE_SEM_POST, semPosted, resumedTask);
⑸      LOS_Schedule();
    } else {
⑹      semPosted->semCount++;
        LOS_IntRestore(intSave);
        OsHookCall(LOS_HOOK_TYPE_SEM_POST, semPosted, resumedTask);
    }
    return LOS_OK;
}
LITE_OS_SEC_TEXT UINT32 OsSemPostUnsafe(UINT32 semHandle, BOOL *needSched)
{
    LosTaskCB *resumedTask = NULL;
    LosSemCB *semPosted = GET_SEM(semHandle);
    if ((semPosted->semID != semHandle) || (semPosted->semStat == OS_SEM_UNUSED)) {
        return LOS_ERRNO_SEM_INVALID;
    }
    /* Update the operate time, no matter the actual Post success or not */
    OsSemDbgTimeUpdateHook(semHandle);
⑴  if (semPosted->semCount == OS_SEM_COUNT_MAX) {
        return LOS_ERRNO_SEM_OVERFLOW;
    }
⑵  if (!LOS_ListEmpty(&semPosted->semList)) {
⑶      resumedTask = OS_TCB_FROM_PENDLIST(LOS_DL_LIST_FIRST(&(semPosted->semList)));
⑷      OsTaskWakeClearPendMask(resumedTask);
        resumedTask->ops->wake(resumedTask);
        if (needSched != NULL) {
⑸          *needSched = TRUE;
        }
    } else {
⑹      semPosted->semCount++;
    }
    OsHookCall(LOS_HOOK_TYPE_SEM_POST, semPosted, resumedTask);
    return LOS_OK;
}
LITE_OS_SEC_TEXT UINT32 LOS_SemPost(UINT32 semHandle)
{
    UINT32 intSave;
    UINT32 ret;
    BOOL needSched = FALSE;

    if (GET_SEM_INDEX(semHandle) >= LOSCFG_BASE_IPC_SEM_LIMIT) {
        return LOS_ERRNO_SEM_INVALID;
    }
    SCHEDULER_LOCK(intSave);
    ret = OsSemPostUnsafe(semHandle, &needSched);
    SCHEDULER_UNLOCK(intSave);
⑺  if (needSched) {
        LOS_MpSchedule(OS_MP_CPU_ALL);
        LOS_Schedule();
    }
    return ret;
}