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Annotation of XNU/iokit/Families/IONetworking/IOPacketQueue.cpp, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * Copyright (c) 1998 Apple Computer, Inc.  All rights reserved. 
        !            24:  *
        !            25:  * IOPacketQueue.cpp - Implements a FIFO mbuf packet queue.
        !            26:  *
        !            27:  * HISTORY
        !            28:  * 9-Dec-1998       Joe Liu (jliu) created.
        !            29:  *
        !            30:  */
        !            31: 
        !            32: #include <IOKit/assert.h>
        !            33: #include <IOKit/IOLib.h>    // IOLog
        !            34: #include <IOKit/network/IOPacketQueue.h>
        !            35: 
        !            36: // Get the mbuf definitions from BSD headers.
        !            37: //
        !            38: extern "C" {
        !            39: #include <sys/param.h>
        !            40: #include <sys/mbuf.h>
        !            41: }
        !            42: 
        !            43: #define super OSObject
        !            44: OSDefineMetaClassAndStructors( IOPacketQueue, OSObject )
        !            45: 
        !            46: //---------------------------------------------------------------------------
        !            47: // Lock macros.
        !            48: 
        !            49: #define LOCK         IOSimpleLockLock(_lock)
        !            50: #define UNLOCK       IOSimpleLockUnlock(_lock)
        !            51: 
        !            52: //---------------------------------------------------------------------------
        !            53: // Factory method that will construct and initialize an IOPacketQueue instance.
        !            54: //
        !            55: // capacity: The initial capacity of the queue. Can be changed
        !            56: //           later through setCapacity().
        !            57: //
        !            58: // Returns an IOPacketQueue instance upon success, or 0 otherwise.
        !            59: 
        !            60: bool IOPacketQueue::initWithCapacity(UInt32 capacity)
        !            61: {
        !            62:     _head = _tail = (struct mbuf *) 0;
        !            63:     _size = _peakSize = 0;
        !            64:     _capacity = capacity;
        !            65: 
        !            66:     if (!super::init()) {
        !            67:         IOLog("IOPacketQueue: super::init() failed\n");
        !            68:         return false;
        !            69:     }
        !            70: 
        !            71:     if ((_lock = IOSimpleLockAlloc()) == 0)
        !            72:         return false;
        !            73: 
        !            74:     IOSimpleLockInit(_lock);
        !            75: 
        !            76:     return true;
        !            77: }
        !            78: 
        !            79: //---------------------------------------------------------------------------
        !            80: // Factory method that will construct and initialize an IOPacketQueue instance.
        !            81: //
        !            82: // capacity: The initial capacity of the queue. Can be changed later
        !            83: //           through setCapacity().
        !            84: //
        !            85: // Returns an IOPacketQueue instance on success, or 0 otherwise.
        !            86: 
        !            87: IOPacketQueue * IOPacketQueue::withCapacity(UInt32 capacity)
        !            88: {
        !            89:     IOPacketQueue * queue = new IOPacketQueue;
        !            90: 
        !            91:     if (queue && !queue->initWithCapacity(capacity)) {
        !            92:         queue->release();
        !            93:         return 0;
        !            94:     }
        !            95:     return queue;
        !            96: }
        !            97: 
        !            98: //---------------------------------------------------------------------------
        !            99: // Frees the IOPacketQueue instance. Release all packets in the queue to the
        !           100: // free mbuf pool, then call super::free().
        !           101: 
        !           102: void IOPacketQueue::free()
        !           103: {
        !           104:     if (_lock) {
        !           105:         setCapacity(0);
        !           106:         lockFlush();
        !           107:         IOSimpleLockFree(_lock);
        !           108:     }
        !           109:     super::free();
        !           110: }
        !           111: 
        !           112: //---------------------------------------------------------------------------
        !           113: // Get the size of the queue.
        !           114: // Returns the number of packets currently held in the queue.
        !           115: 
        !           116: UInt32 IOPacketQueue::getSize() const
        !           117: {
        !           118:     return (_size);
        !           119: }
        !           120: 
        !           121: //---------------------------------------------------------------------------
        !           122: // The queue contains a counter that records the peak size of the queue.
        !           123: // This method returns the value in the counter, and can optionally reset
        !           124: // the counter back to zero.
        !           125: //
        !           126: // reset: Reset the peak size counter to zero if true.
        !           127: //
        !           128: // Returns the peak size count.
        !           129: 
        !           130: UInt32 IOPacketQueue::getPeakSize(bool reset = false)
        !           131: {
        !           132:     UInt32 peak = _peakSize;
        !           133:     if (reset)
        !           134:         _peakSize = 0;
        !           135:     return peak;
        !           136: }
        !           137: 
        !           138: //---------------------------------------------------------------------------
        !           139: // Adjust the queue's capacity. If the capacity is set to a value that
        !           140: // is smaller than its current size, then the queue will drop incoming packets,
        !           141: // but existing packets in the queue will remain intact.
        !           142: //
        !           143: // capacity: The new capacity.
        !           144: //
        !           145: // Returns true if the new capacity was accepted, false otherwise.
        !           146: 
        !           147: bool IOPacketQueue::setCapacity(UInt32 capacity)
        !           148: {
        !           149:     LOCK;
        !           150:     _capacity = capacity;
        !           151:     UNLOCK;
        !           152:     return true;
        !           153: }
        !           154: 
        !           155: //---------------------------------------------------------------------------
        !           156: // Get the capacity of the queue.
        !           157: // Returns the current queue capacity.
        !           158: 
        !           159: UInt32 IOPacketQueue::getCapacity() const
        !           160: {
        !           161:     return _capacity;
        !           162: }
        !           163: 
        !           164: //---------------------------------------------------------------------------
        !           165: // Peek at the head of the queue without dequeueing the packet.
        !           166: // An ensuing call to peek() or dequeue() will return the same packet.
        !           167: // Returns the packet at the head of the queue. The caller must not modify
        !           168: // the packet returned.
        !           169: // Return the packet at the head of the queue.
        !           170: 
        !           171: const struct mbuf * IOPacketQueue::peek() const
        !           172: {
        !           173:     return (_head);
        !           174: }
        !           175: 
        !           176: //---------------------------------------------------------------------------
        !           177: // Queueing macros.
        !           178: 
        !           179: static inline UInt32 _freePacketChain(struct mbuf * m)
        !           180: {
        !           181:     UInt32 count = 0;
        !           182:     struct mbuf * ml;
        !           183: 
        !           184:     while ((ml = m)) {
        !           185:         m = ml->m_nextpkt;
        !           186:         ml->m_nextpkt = 0;
        !           187:         m_freem(ml);
        !           188:         count++;
        !           189:     }
        !           190: 
        !           191:     return count;
        !           192: }
        !           193: 
        !           194: static inline void _prepend(
        !           195:     struct mbuf * m,        /* not modified */
        !           196:     struct mbuf * & head,   /* modified */
        !           197:     struct mbuf * & tail,   /* modified */
        !           198:     UInt32 & size)          /* modified */
        !           199: {
        !           200:     assert(m);
        !           201: 
        !           202:     if (size++ > 0) {
        !           203:         struct mbuf * mtail = m;
        !           204:         while (mtail->m_nextpkt) {
        !           205:             mtail = mtail->m_nextpkt;
        !           206:             size++;
        !           207:         }
        !           208: 
        !           209:         assert(head);
        !           210:         mtail->m_nextpkt = head;
        !           211:         head = m;
        !           212:     }
        !           213:     else {
        !           214:         assert(!head && !tail);
        !           215:         head = tail = m;
        !           216:         while (tail->m_nextpkt) {
        !           217:             tail = tail->m_nextpkt;
        !           218:             size++;
        !           219:         }
        !           220:     }
        !           221: } 
        !           222: 
        !           223: static inline struct mbuf * _enqueue(
        !           224:     struct mbuf * m,        /* mbuf chain to append to tail */
        !           225:     struct mbuf * & head,   /* modified */
        !           226:     struct mbuf * & tail,   /* modified */
        !           227:     UInt32 capacity,        /* not modified */
        !           228:     UInt32 & size,          /* modified */
        !           229:     UInt32 & peakSize)      /* modified */
        !           230: {
        !           231:     assert(m);
        !           232: 
        !           233:     if (size >= capacity)
        !           234:         goto overflow;
        !           235: 
        !           236:     if (size++ > 0) {
        !           237:         assert(tail);
        !           238:         tail->m_nextpkt = m;
        !           239:         tail = m;
        !           240:     }
        !           241:     else {
        !           242:         assert(!head && !tail);
        !           243:         head = tail = m;
        !           244:     }
        !           245:     
        !           246:     m = 0;
        !           247: 
        !           248:     while (tail->m_nextpkt) {
        !           249:         if (size >= capacity) {
        !           250:             m = tail->m_nextpkt;
        !           251:             tail->m_nextpkt = 0;
        !           252:             goto overflow;
        !           253:         }
        !           254: 
        !           255:         tail = tail->m_nextpkt;
        !           256:         size++;
        !           257:     }
        !           258: 
        !           259:     if (size > peakSize)
        !           260:         peakSize = size;
        !           261: 
        !           262: overflow:
        !           263:     return m;
        !           264: }
        !           265: 
        !           266: static inline struct mbuf * _dequeue(
        !           267:     struct mbuf * & head,   /* modified */
        !           268:     struct mbuf * & tail,   /* modified */
        !           269:     UInt32 & size)          /* modified */
        !           270: {
        !           271:     if (size == 0)
        !           272:         return 0;
        !           273: 
        !           274:     assert(head);
        !           275: 
        !           276:     struct mbuf *m = head;
        !           277:     head = head->m_nextpkt;
        !           278:     m->m_nextpkt = 0;
        !           279:     if (--size == 0)
        !           280:         head = tail = 0;
        !           281: 
        !           282:     return m;
        !           283: }
        !           284: 
        !           285: static inline struct mbuf * _dequeueAll(
        !           286:     struct mbuf * & head,   /* modified */
        !           287:     struct mbuf * & tail,   /* modified */
        !           288:     UInt32 & size)          /* modified */
        !           289: {
        !           290:     if (size == 0)
        !           291:         return 0;
        !           292:     
        !           293:     assert(head);
        !           294: 
        !           295:     struct mbuf *m = head;
        !           296:     head = tail = 0;
        !           297:     size = 0;
        !           298: 
        !           299:     return m;
        !           300: }
        !           301: 
        !           302: //---------------------------------------------------------------------------
        !           303: // Traverse a packet chain linked through the mbuf nextpkt field, and free
        !           304: // each packet.
        !           305: //
        !           306: // m: The mbuf at the head of the mbuf chain.
        !           307: //
        !           308: // Returns the number of mbufs freed.
        !           309: 
        !           310: UInt32 IOPacketQueue::freePacketChain(struct mbuf * m)
        !           311: {
        !           312:     return _freePacketChain(m);
        !           313: }
        !           314: 
        !           315: //---------------------------------------------------------------------------
        !           316: // Add a packet (or a packet chain) to the head of the queue. Unlike enqueue(),
        !           317: // the capacity is not checked, and the input packet is never dropped.
        !           318: //
        !           319: // m: A single packet, or packet chain, to be added to the head of the queue.
        !           320: 
        !           321: void IOPacketQueue::prepend(struct mbuf * m)
        !           322: {
        !           323:     _prepend(m, _head, _tail, _size);
        !           324: }
        !           325: 
        !           326: //---------------------------------------------------------------------------
        !           327: // Add a packet (or a packet chain) to the tail of the queue.
        !           328: //
        !           329: // m: A single packet, or a packet chain, to be added to the tail of the queue.
        !           330: 
        !           331: UInt32 IOPacketQueue::enqueue(struct mbuf * m)
        !           332: {
        !           333:     m = _enqueue(m, _head, _tail, _capacity, _size, _peakSize);
        !           334:     return (m ? _freePacketChain(m) : 0);
        !           335: }
        !           336: 
        !           337: //---------------------------------------------------------------------------
        !           338: // Remove a single packet from the head of the queue.
        !           339: //
        !           340: // Returns the dequeued packet. A NULL is returned if the queue is empty.
        !           341: 
        !           342: struct mbuf * IOPacketQueue::dequeue()
        !           343: {   
        !           344:     return _dequeue(_head, _tail, _size);
        !           345: }
        !           346: 
        !           347: //---------------------------------------------------------------------------
        !           348: // Removes all packets from the queue and return the first packet of the
        !           349: // packet chain.
        !           350: //
        !           351: // Returns the head of the dequeued packet chain.
        !           352: 
        !           353: struct mbuf * IOPacketQueue::dequeueAll()
        !           354: {
        !           355:     return _dequeueAll(_head, _tail, _size);
        !           356: }
        !           357: 
        !           358: //---------------------------------------------------------------------------
        !           359: // Removes all packets from the queue and put them back to the free mbuf
        !           360: // pool. The size of the queue will be zero after the call.
        !           361: //
        !           362: // Returns the number of packets freed.
        !           363: 
        !           364: UInt32 IOPacketQueue::flush()
        !           365: {
        !           366:     return (freePacketChain(dequeueAll()));
        !           367: }
        !           368: 
        !           369: //---------------------------------------------------------------------------
        !           370: // Locked forms of prepend/enqueue/dequeue/dequeueAll methods.
        !           371: // A spinlock is used to enforce mutual exclusion between methods that
        !           372: // with a "lock" prefix.
        !           373: 
        !           374: void IOPacketQueue::lockPrepend(struct mbuf * m)
        !           375: {
        !           376:     LOCK;
        !           377:     _prepend(m, _head, _tail, _size);
        !           378:     UNLOCK;  
        !           379: }
        !           380: 
        !           381: UInt32 IOPacketQueue::lockEnqueue(struct mbuf * m)
        !           382: {
        !           383:     LOCK;
        !           384:     m = _enqueue(m, _head, _tail, _capacity, _size, _peakSize);
        !           385:     UNLOCK;
        !           386:     return (m ? _freePacketChain(m) : 0);
        !           387: }
        !           388: 
        !           389: struct mbuf * IOPacketQueue::lockDequeue()
        !           390: {
        !           391:     struct mbuf * m;
        !           392:     LOCK;
        !           393:     m = _dequeue(_head, _tail, _size);
        !           394:     UNLOCK;
        !           395:     return m;
        !           396: }
        !           397: 
        !           398: struct mbuf * IOPacketQueue::lockDequeueAll()
        !           399: {
        !           400:     struct mbuf * m;
        !           401:     LOCK;
        !           402:     m = _dequeueAll(_head, _tail, _size);
        !           403:     UNLOCK;
        !           404:     return m;
        !           405: }
        !           406: 
        !           407: UInt32 IOPacketQueue::lockFlush()
        !           408: {
        !           409:     return (freePacketChain(lockDequeueAll()));
        !           410: }

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