The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_power.c

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    1 /*-
    2  * Copyright (c) 2002-2007 Sam Leffler, Errno Consulting
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   24  */
   25 
   26 #include <sys/cdefs.h>
   27 __FBSDID("$FreeBSD: releng/7.4/sys/net80211/ieee80211_power.c 187739 2009-01-26 20:24:04Z dwhite $");
   28 
   29 /*
   30  * IEEE 802.11 power save support.
   31  */
   32 #include <sys/param.h>
   33 #include <sys/systm.h> 
   34 #include <sys/kernel.h>
   35  
   36 #include <sys/socket.h>
   37 
   38 #include <net/if.h>
   39 #include <net/if_media.h>
   40 #include <net/ethernet.h>
   41 
   42 #include <net80211/ieee80211_var.h>
   43 
   44 #include <net/bpf.h>
   45 
   46 static void ieee80211_set_tim(struct ieee80211_node *ni, int set);
   47 
   48 void
   49 ieee80211_power_attach(struct ieee80211com *ic)
   50 {
   51         /* NB: driver should override */
   52         ic->ic_set_tim = ieee80211_set_tim;
   53 }
   54 
   55 void
   56 ieee80211_power_lateattach(struct ieee80211com *ic)
   57 {
   58         ic->ic_tim_len = howmany(ic->ic_max_aid,8) * sizeof(uint8_t);
   59         MALLOC(ic->ic_tim_bitmap, uint8_t *, ic->ic_tim_len,
   60                 M_DEVBUF, M_NOWAIT | M_ZERO);
   61         if (ic->ic_tim_bitmap == NULL) {
   62                 printf("%s: no memory for TIM bitmap!\n", __func__);
   63                 /* XXX good enough to keep from crashing? */
   64                 ic->ic_tim_len = 0;
   65         }
   66 }
   67 
   68 void
   69 ieee80211_power_detach(struct ieee80211com *ic)
   70 {
   71         if (ic->ic_tim_bitmap != NULL) {
   72                 FREE(ic->ic_tim_bitmap, M_DEVBUF);
   73                 ic->ic_tim_bitmap = NULL;
   74         }
   75 }
   76 
   77 /*
   78  * Clear any frames queued on a node's power save queue.
   79  * The number of frames that were present is returned.
   80  */
   81 int
   82 ieee80211_node_saveq_drain(struct ieee80211_node *ni)
   83 {
   84         int qlen;
   85 
   86         IEEE80211_NODE_SAVEQ_LOCK(ni);
   87         qlen = IEEE80211_NODE_SAVEQ_QLEN(ni);
   88         _IF_DRAIN(&ni->ni_savedq);
   89         IEEE80211_NODE_SAVEQ_UNLOCK(ni);
   90 
   91         return qlen;
   92 }
   93 
   94 /*
   95  * Age frames on the power save queue. The aging interval is
   96  * 4 times the listen interval specified by the station.  This
   97  * number is factored into the age calculations when the frame
   98  * is placed on the queue.  We store ages as time differences
   99  * so we can check and/or adjust only the head of the list.
  100  * If a frame's age exceeds the threshold then discard it.
  101  * The number of frames discarded is returned so the caller
  102  * can check if it needs to adjust the tim.
  103  */
  104 int
  105 ieee80211_node_saveq_age(struct ieee80211_node *ni)
  106 {
  107         int discard = 0;
  108 
  109         if (IEEE80211_NODE_SAVEQ_QLEN(ni) != 0) {
  110                 struct mbuf *m;
  111 
  112                 IEEE80211_NODE_SAVEQ_LOCK(ni);
  113                 while (IF_POLL(&ni->ni_savedq, m) != NULL &&
  114                      M_AGE_GET(m) < IEEE80211_INACT_WAIT) {
  115 IEEE80211_DPRINTF(ni->ni_ic, IEEE80211_MSG_POWER, "[%s] discard frame, age %u\n", ether_sprintf(ni->ni_macaddr), M_AGE_GET(m));/*XXX*/
  116                         _IEEE80211_NODE_SAVEQ_DEQUEUE_HEAD(ni, m);
  117                         m_freem(m);
  118                         discard++;
  119                 }
  120                 if (m != NULL)
  121                         M_AGE_SUB(m, IEEE80211_INACT_WAIT);
  122                 IEEE80211_NODE_SAVEQ_UNLOCK(ni);
  123 
  124                 IEEE80211_NOTE(ni->ni_ic, IEEE80211_MSG_POWER, ni,
  125                     "discard %u frames for age", discard);
  126                 IEEE80211_NODE_STAT_ADD(ni, ps_discard, discard);
  127         }
  128         return discard;
  129 }
  130 
  131 /*
  132  * Indicate whether there are frames queued for a station in power-save mode.
  133  */
  134 static void
  135 ieee80211_set_tim(struct ieee80211_node *ni, int set)
  136 {
  137         struct ieee80211com *ic = ni->ni_ic;
  138         uint16_t aid;
  139 
  140         KASSERT(ic->ic_opmode == IEEE80211_M_HOSTAP ||
  141                 ic->ic_opmode == IEEE80211_M_IBSS,
  142                 ("operating mode %u", ic->ic_opmode));
  143 
  144         aid = IEEE80211_AID(ni->ni_associd);
  145         KASSERT(aid < ic->ic_max_aid,
  146                 ("bogus aid %u, max %u", aid, ic->ic_max_aid));
  147 
  148         IEEE80211_BEACON_LOCK(ic);
  149         if (set != (isset(ic->ic_tim_bitmap, aid) != 0)) {
  150                 if (set) {
  151                         setbit(ic->ic_tim_bitmap, aid);
  152                         ic->ic_ps_pending++;
  153                 } else {
  154                         clrbit(ic->ic_tim_bitmap, aid);
  155                         ic->ic_ps_pending--;
  156                 }
  157                 /* NB: we know ic is in RUN state so no need to check */
  158                 ic->ic_update_beacon(ic, IEEE80211_BEACON_TIM);
  159         }
  160         IEEE80211_BEACON_UNLOCK(ic);
  161 }
  162 
  163 /*
  164  * Save an outbound packet for a node in power-save sleep state.
  165  * The new packet is placed on the node's saved queue, and the TIM
  166  * is changed, if necessary.
  167  */
  168 void
  169 ieee80211_pwrsave(struct ieee80211_node *ni, struct mbuf *m)
  170 {
  171         struct ieee80211com *ic = ni->ni_ic;
  172         int qlen, age;
  173 
  174         IEEE80211_NODE_SAVEQ_LOCK(ni);
  175         if (_IF_QFULL(&ni->ni_savedq)) {
  176                 _IF_DROP(&ni->ni_savedq);
  177                 IEEE80211_NODE_SAVEQ_UNLOCK(ni);
  178                 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY,
  179                         "[%s] pwr save q overflow, drops %d (size %d)\n",
  180                         ether_sprintf(ni->ni_macaddr), 
  181                         ni->ni_savedq.ifq_drops, IEEE80211_PS_MAX_QUEUE);
  182 #ifdef IEEE80211_DEBUG
  183                 if (ieee80211_msg_dumppkts(ic))
  184                         ieee80211_dump_pkt(ic, mtod(m, caddr_t), m->m_len, -1, -1);
  185 #endif
  186                 m_freem(m);
  187                 return;
  188         }
  189         /*
  190          * Tag the frame with it's expiry time and insert
  191          * it in the queue.  The aging interval is 4 times
  192          * the listen interval specified by the station. 
  193          * Frames that sit around too long are reclaimed
  194          * using this information.
  195          */
  196         /* TU -> secs.  XXX handle overflow? */
  197         age = IEEE80211_TU_TO_MS((ni->ni_intval * ic->ic_bintval) << 2) / 1000;
  198         _IEEE80211_NODE_SAVEQ_ENQUEUE(ni, m, qlen, age);
  199         IEEE80211_NODE_SAVEQ_UNLOCK(ni);
  200 
  201         IEEE80211_DPRINTF(ic, IEEE80211_MSG_POWER,
  202                 "[%s] save frame with age %d, %u now queued\n",
  203                 ether_sprintf(ni->ni_macaddr), age, qlen);
  204 
  205         if (qlen == 1 && ic->ic_set_tim != NULL)
  206                 ic->ic_set_tim(ni, 1);
  207 }
  208 
  209 /*
  210  * Handle station power-save state change.
  211  */
  212 void
  213 ieee80211_node_pwrsave(struct ieee80211_node *ni, int enable)
  214 {
  215         struct ieee80211com *ic = ni->ni_ic;
  216         struct mbuf *m, *mhead, *mtail;
  217         int mcount;
  218 
  219         if (enable) {
  220                 if ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) == 0)
  221                         ic->ic_ps_sta++;
  222                 ni->ni_flags |= IEEE80211_NODE_PWR_MGT;
  223                 IEEE80211_NOTE(ic, IEEE80211_MSG_POWER, ni,
  224                     "power save mode on, %u sta's in ps mode", ic->ic_ps_sta);
  225                 return;
  226         }
  227 
  228         if (ni->ni_flags & IEEE80211_NODE_PWR_MGT)
  229                 ic->ic_ps_sta--;
  230         ni->ni_flags &= ~IEEE80211_NODE_PWR_MGT;
  231         IEEE80211_NOTE(ic, IEEE80211_MSG_POWER, ni,
  232             "power save mode off, %u sta's in ps mode", ic->ic_ps_sta);
  233         /* XXX if no stations in ps mode, flush mc frames */
  234 
  235         /*
  236          * Flush queued unicast frames.
  237          */
  238         if (IEEE80211_NODE_SAVEQ_QLEN(ni) == 0) {
  239                 if (ic->ic_set_tim != NULL)
  240                         ic->ic_set_tim(ni, 0);          /* just in case */
  241                 return;
  242         }
  243         IEEE80211_NOTE(ic, IEEE80211_MSG_POWER, ni,
  244             "flush ps queue, %u packets queue", IEEE80211_NODE_SAVEQ_QLEN(ni));
  245         /*
  246          * Unload the frames from the ps q but don't send them
  247          * to the driver yet.  We do this in two stages to minimize
  248          * locking but also because there's no easy way to preserve
  249          * ordering given the existing ifnet access mechanisms.
  250          * XXX could be optimized
  251          */
  252         IEEE80211_NODE_SAVEQ_LOCK(ni);
  253         mcount = IEEE80211_NODE_SAVEQ_QLEN(ni);
  254         mhead = mtail = NULL;
  255         for (;;) {
  256                 _IEEE80211_NODE_SAVEQ_DEQUEUE_HEAD(ni, m);
  257                 if (m == NULL)
  258                         break;
  259                 if (mhead == NULL) {
  260                         mhead = m;
  261                         m->m_nextpkt = NULL;
  262                 } else
  263                         mtail->m_nextpkt = m;
  264                 mtail = m;
  265         }
  266         IEEE80211_NODE_SAVEQ_UNLOCK(ni);
  267         if (mhead != NULL) {
  268                 /* XXX need different driver interface */
  269                 /* XXX bypasses q max */
  270                 IF_PREPEND_LIST(&ic->ic_ifp->if_snd, mhead, mtail, mcount);
  271         }
  272         if (ic->ic_set_tim != NULL)
  273                 ic->ic_set_tim(ni, 0);
  274 }
  275 
  276 /*
  277  * Handle power-save state change in station mode.
  278  */
  279 void
  280 ieee80211_sta_pwrsave(struct ieee80211com *ic, int enable)
  281 {
  282         struct ieee80211_node *ni = ic->ic_bss;
  283         int qlen;
  284 
  285         if (!((enable != 0) ^ ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) != 0)))
  286                 return;
  287 
  288         IEEE80211_NOTE(ic, IEEE80211_MSG_POWER, ni,
  289             "sta power save mode %s", enable ? "on" : "off");
  290         if (!enable) {
  291                 ni->ni_flags &= ~IEEE80211_NODE_PWR_MGT;
  292                 ieee80211_send_nulldata(ieee80211_ref_node(ni));
  293                 /*
  294                  * Flush any queued frames; we can do this immediately
  295                  * because we know they'll be queued behind the null
  296                  * data frame we send the ap.
  297                  * XXX can we use a data frame to take us out of ps?
  298                  */
  299                 qlen = IEEE80211_NODE_SAVEQ_QLEN(ni);
  300                 if (qlen != 0) {
  301                         IEEE80211_NOTE(ic, IEEE80211_MSG_POWER, ni,
  302                             "flush ps queue, %u packets queued", qlen);
  303                         for (;;) {
  304                                 struct mbuf *m;
  305 
  306                                 IEEE80211_NODE_SAVEQ_LOCK(ni);
  307                                 _IEEE80211_NODE_SAVEQ_DEQUEUE_HEAD(ni, m);
  308                                 IEEE80211_NODE_SAVEQ_UNLOCK(ni);
  309                                 if (m == NULL)
  310                                         break;
  311                                 /* XXX need different driver interface */
  312                                 /* XXX bypasses q max */
  313                                 IF_ENQUEUE(&ic->ic_ifp->if_snd, m);
  314                         }
  315                 }
  316         } else {
  317                 ni->ni_flags |= IEEE80211_NODE_PWR_MGT;
  318                 ieee80211_send_nulldata(ieee80211_ref_node(ni));
  319         }
  320 }

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