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neelimap
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/* hookTblLibP.h - Private generic hook management library header */
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/*
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* Copyright (c) 2012 Wind River Systems, Inc.
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*
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* The right to copy, distribute, modify or otherwise make use
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* of this software may be licensed only pursuant to the terms
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* of an applicable Wind River license agreement.
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*/
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/*
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modification history
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--------------------
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01b,27nov12,jpb fixed value of HOOK_TABLE_STATUS_BITS (WIND00392252)
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01a,27apr12,cww written
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*/
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#ifndef __INChookTblLibPh
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#define __INChookTblLibPh
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#include <vxWorks.h>
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#include <private/qLibP.h>
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#include <hookLib.h>
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#include <semLib.h>
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#include <vxAtomicLib.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef _ASMLANGUAGE
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typedef struct
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{
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VX_SEMAPHORE (lockSem);
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int maxEntries;
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int execCnt;
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Q_HEAD updatePendQ;
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void * pActiveTable;
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void ** hookTableA;
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void ** hookTableB;
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} HOOK_TBL;
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#define HOOK_TBL_DECL(name, maxEntries) \
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void * name##ArrayA[maxEntries+1]; \
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void * name##ArrayB[maxEntries+1]; \
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HOOK_TBL name = {{},maxEntries,0,{},name##ArrayA,name##ArrayA, \
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name##ArrayB};
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/*
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* Notes on the protection mechanisms used:
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*
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* Table updaters use a mutex (lockSem) to protect the table from simultaneous
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* updates. Two copies of the actual hooks are maintained, one of which is
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* always active and referenced by pActiveTable. Updating the hooks involves
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* first updating the inactive table, flipping pActiveTable, then updating the
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* other (now inactive) table.
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*
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* The mutex is not used for walking the table as we cannot pend when
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* invoking hooks. Instead, bit manipulation of pActiveTable is used to mark
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* when the table is being traversed, also serving to prevent pActiveTable
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* from being swapped during hook invokation. A count (execCnt) is used to
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* track nested and concurrent execution.
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*
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* The following status bits are stored in the least significant bits of
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* pActiveTable and are used to protect the table from updates while it is
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* being traversed. Setting HOOK_TABLE_IN_USE indicates that the table is
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* reserved, while setting HOOK_TABLE_RESERVING indicates that the most recent
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* operation is a reservation. The latter is required to detect the situation
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* where the table is being reserved while an unreserve operation has already
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* decremented execCnt to 0, but before the HOOK_TABLE_IN_USE bit is cleared,
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* in which case the table should stay reserved.
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*/
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#define HOOK_TABLE_IN_USE 0x01L
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#define HOOK_TABLE_RESERVING 0x02L
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#define HOOK_TABLE_STATUS_BITS (HOOK_TABLE_IN_USE | HOOK_TABLE_RESERVING)
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/******************************************************************************
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*
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* HOOK_TBL_READ_RESERVE - Reserve the active hook table for walking
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*
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* Marks the given HOOK_TBL as in use and returns a pointer to the active
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* table via <pReservedTable>.
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*
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* \NOMANUAL
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*/
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#define HOOK_TBL_READ_RESERVE(pReservedTable,pHookTable) \
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{ \
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pReservedTable = (void *) vxAtomicOr ( \
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(atomic_t *) &(pHookTable)->pActiveTable, \
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HOOK_TABLE_STATUS_BITS); \
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vxAtomic32Inc (&(pHookTable)->execCnt); \
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pReservedTable = (void *)((ULONG) pReservedTable & \
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~HOOK_TABLE_STATUS_BITS); \
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}
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/******************************************************************************
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*
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* HOOK_TBL_READ_UNRESERVE - Unreserve the active hook table
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*
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* Marks the given HOOK_TBL as not in use and potentially unpends any task
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* waiting to update the table. Note that the CAS only fails if either another
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* task sets the reserving bit, or we were preempted just before the CAS and
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* someone else has unreserved already; in both cases, there is nothing more
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* to do.
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*
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* \NOMANUAL
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*/
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#define HOOK_TBL_READ_UNRESERVE(pHookTable) \
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{ \
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atomic_t tempVal; \
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\
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tempVal = vxAtomicAnd ((atomic_t *) &(pHookTable)->pActiveTable, \
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~HOOK_TABLE_RESERVING); \
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tempVal &= ~HOOK_TABLE_RESERVING; \
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\
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if (vxAtomic32Dec (&(pHookTable)->execCnt) == 1) \
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{ \
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if (vxAtomicCas ((atomic_t *) &(pHookTable)->pActiveTable, \
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tempVal, \
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tempVal & ~(HOOK_TABLE_STATUS_BITS))) \
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hookTblUpdatersUnpend (pHookTable); \
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} \
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}
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/******************************************************************************
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*
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* HOOK_TBL_READ_UNRESERVE_NO_UNPEND - Unreserve the active hook table
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*
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* Marks the given HOOK_TBL as not in use but does not unpend any waiting task.
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* Used only in special cases where we cannot enter the kernel, such as when
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* running reboot hooks. We skip the reserving bit check since in these
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* special cases we either don't care or no concurrent reserve is possible.
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*
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* \NOMANUAL
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*/
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#define HOOK_TBL_READ_UNRESERVE_NO_UNPEND(pHookTable) \
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{ \
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if (vxAtomic32Dec (&(pHookTable)->execCnt) == 1) \
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{ \
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vxAtomicAnd ((atomic_t *) &(pHookTable)->pActiveTable, \
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~HOOK_TABLE_STATUS_BITS); \
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} \
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}
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/******************************************************************************
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*
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* HOOK_TBL_INVOKE_VOID_RETURN - Invoke all hooks in the given table.
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*
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* This macro calls all hook functions added into the given hook table <tbl>.
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* The called functions are not expected to return anything (return values
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* are not checked). The <type> argument is a typecast that is applied to
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* all function pointers in the table. This is done for type checking
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* purposes. The <arglist> argument is a parenthesis-enclosed
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* argument list that is passed verbatim to each hook function called.
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*
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* \NOMANUAL
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*/
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#define HOOK_TBL_INVOKE_VOID_RETURN(pTbl,type,arglist) \
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{ \
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int ix; \
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void ** pTableCurrent; \
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\
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HOOK_TBL_READ_RESERVE (pTableCurrent,pTbl); \
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\
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for (ix = 0; ix < (pTbl)->maxEntries; ix++) \
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{ \
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if (pTableCurrent[ix] != NULL) \
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(*(type) pTableCurrent[ix]) arglist; \
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else \
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break; \
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} \
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\
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HOOK_TBL_READ_UNRESERVE (pTbl); \
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}
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/******************************************************************************
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*
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* HOOK_TBL_INVOKE_CHECK_RETURN - Invoke all hooks in a table, performing
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* return value checking.
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*
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* This macro calls all hook functions added into the given hook table <tbl>.
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* The return value from each called function is saved to <pRetval> and
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* compared with <keepGoing>, and hook execution stops if they differ. In that
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* case, any remaining hooks are not executed. The <type> argument is a
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* typecast that is applied to all function pointers in the table. This is
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* done for type checking purposes. The <arglist> must be a parenthesis-enclosed
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* argument list that is passed verbatim to each hook function called.
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*
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* \NOMANUAL
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*/
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#define HOOK_TBL_INVOKE_CHECK_RETURN(pTbl,type,keepGoing,pRetval,arglist) \
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{ \
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int ix; \
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void ** pTableCurrent; \
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\
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HOOK_TBL_READ_RESERVE (pTableCurrent,pTbl); \
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\
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for (ix = 0; ix < (pTbl)->maxEntries; ix++) \
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{ \
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if (pTableCurrent[ix] != NULL) \
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{ \
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*(pRetval) = (type) pTableCurrent[ix] arglist; \
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if (*(pRetval) != keepGoing) \
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{ \
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break; \
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} \
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} \
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else \
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break; \
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} \
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\
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HOOK_TBL_READ_UNRESERVE (pTbl); \
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}
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/* function declarations */
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STATUS hookTblInit (HOOK_TBL * pTable);
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STATUS hookTblAddToTail (HOOK_TBL * pTable, void * hook);
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STATUS hookTblAddToHead (HOOK_TBL * pTable, void * hook);
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STATUS hookTblDelete (HOOK_TBL * pTable, void * hook);
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BOOL hookTblFind (HOOK_TBL * pTable, void * hook);
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void hookTblUpdatersUnpend (HOOK_TBL * pTable);
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void hookTblShow (HOOK_TBL * pHookTable);
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#endif /* _ASMLANGUAGE */
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#ifdef __cplusplus
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}
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#endif
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#endif /* __INChookTblLibPh */
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