net/rxrpc/krxiod.c

   1 /* krxiod.c: Rx I/O daemon
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/completion.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/init.h>
  16 #include <linux/freezer.h>
  17 #include <rxrpc/krxiod.h>
  18 #include <rxrpc/transport.h>
  19 #include <rxrpc/peer.h>
  20 #include <rxrpc/call.h>
  21 #include "internal.h"
  22
  23 static DECLARE_WAIT_QUEUE_HEAD(rxrpc_krxiod_sleepq);
  24 static DECLARE_COMPLETION(rxrpc_krxiod_dead);
  25
  26 static atomic_t rxrpc_krxiod_qcount = ATOMIC_INIT(0);
  27
  28 static LIST_HEAD(rxrpc_krxiod_transportq);
  29 static DEFINE_SPINLOCK(rxrpc_krxiod_transportq_lock);
  30
  31 static LIST_HEAD(rxrpc_krxiod_callq);
  32 static DEFINE_SPINLOCK(rxrpc_krxiod_callq_lock);
  33
  34 static volatile int rxrpc_krxiod_die;
  35
  36 /*****************************************************************************/
  37 /*
  38  * Rx I/O daemon
  39  */
  40 static int rxrpc_krxiod(void *arg)
  41 {
  42         DECLARE_WAITQUEUE(krxiod,current);
  43
  44         printk("Started krxiod %d\n",current->pid);
  45
  46         daemonize("krxiod");
  47
  48         /* loop around waiting for work to do */
  49         do {
  50                 /* wait for work or to be told to exit */
  51                 _debug("### Begin Wait");
  52                 if (!atomic_read(&rxrpc_krxiod_qcount)) {
  53                         set_current_state(TASK_INTERRUPTIBLE);
  54
  55                         add_wait_queue(&rxrpc_krxiod_sleepq, &krxiod);
  56
  57                         for (;;) {
  58                                 set_current_state(TASK_INTERRUPTIBLE);
  59                                 if (atomic_read(&rxrpc_krxiod_qcount) ||
  60                                     rxrpc_krxiod_die ||
  61                                     signal_pending(current))
  62                                         break;
  63
  64                                 schedule();
  65                         }
  66
  67                         remove_wait_queue(&rxrpc_krxiod_sleepq, &krxiod);
  68                         set_current_state(TASK_RUNNING);
  69                 }
  70                 _debug("### End Wait");
  71
  72                 /* do work if been given some to do */
  73                 _debug("### Begin Work");
  74
  75                 /* see if there's a transport in need of attention */
  76                 if (!list_empty(&rxrpc_krxiod_transportq)) {
  77                         struct rxrpc_transport *trans = NULL;
  78
  79                         spin_lock_irq(&rxrpc_krxiod_transportq_lock);
  80
  81                         if (!list_empty(&rxrpc_krxiod_transportq)) {
  82                                 trans = list_entry(
  83                                         rxrpc_krxiod_transportq.next,
  84                                         struct rxrpc_transport,
  85                                         krxiodq_link);
  86
  87                                 list_del_init(&trans->krxiodq_link);
  88                                 atomic_dec(&rxrpc_krxiod_qcount);
  89
  90                                 /* make sure it hasn't gone away and doesn't go
  91                                  * away */
  92                                 if (atomic_read(&trans->usage)>0)
  93                                         rxrpc_get_transport(trans);
  94                                 else
  95                                         trans = NULL;
  96                         }
  97
  98                         spin_unlock_irq(&rxrpc_krxiod_transportq_lock);
  99
 100                         if (trans) {
 101                                 rxrpc_trans_receive_packet(trans);
 102                                 rxrpc_put_transport(trans);
 103                         }
 104                 }
 105
 106                 /* see if there's a call in need of attention */
 107                 if (!list_empty(&rxrpc_krxiod_callq)) {
 108                         struct rxrpc_call *call = NULL;
 109
 110                         spin_lock_irq(&rxrpc_krxiod_callq_lock);
 111
 112                         if (!list_empty(&rxrpc_krxiod_callq)) {
 113                                 call = list_entry(rxrpc_krxiod_callq.next,
 114                                                   struct rxrpc_call,
 115                                                   rcv_krxiodq_lk);
 116                                 list_del_init(&call->rcv_krxiodq_lk);
 117                                 atomic_dec(&rxrpc_krxiod_qcount);
 118
 119                                 /* make sure it hasn't gone away and doesn't go
 120                                  * away */
 121                                 if (atomic_read(&call->usage) > 0) {
 122                                         _debug("@@@ KRXIOD"
 123                                                " Begin Attend Call %p", call);
 124                                         rxrpc_get_call(call);
 125                                 }
 126                                 else {
 127                                         call = NULL;
 128                                 }
 129                         }
 130
 131                         spin_unlock_irq(&rxrpc_krxiod_callq_lock);
 132
 133                         if (call) {
 134                                 rxrpc_call_do_stuff(call);
 135                                 rxrpc_put_call(call);
 136                                 _debug("@@@ KRXIOD End Attend Call %p", call);
 137                         }
 138                 }
 139
 140                 _debug("### End Work");
 141
 142                 try_to_freeze();
 143
 144                 /* discard pending signals */
 145                 rxrpc_discard_my_signals();
 146
 147         } while (!rxrpc_krxiod_die);
 148
 149         /* and that's all */
 150         complete_and_exit(&rxrpc_krxiod_dead, 0);
 151
 152 } /* end rxrpc_krxiod() */
 153
 154 /*****************************************************************************/
 155 /*
 156  * start up a krxiod daemon
 157  */
 158 int __init rxrpc_krxiod_init(void)
 159 {
 160         return kernel_thread(rxrpc_krxiod, NULL, 0);
 161
 162 } /* end rxrpc_krxiod_init() */
 163
 164 /*****************************************************************************/
 165 /*
 166  * kill the krxiod daemon and wait for it to complete
 167  */
 168 void rxrpc_krxiod_kill(void)
 169 {
 170         rxrpc_krxiod_die = 1;
 171         wake_up_all(&rxrpc_krxiod_sleepq);
 172         wait_for_completion(&rxrpc_krxiod_dead);
 173
 174 } /* end rxrpc_krxiod_kill() */
 175
 176 /*****************************************************************************/
 177 /*
 178  * queue a transport for attention by krxiod
 179  */
 180 void rxrpc_krxiod_queue_transport(struct rxrpc_transport *trans)
 181 {
 182         unsigned long flags;
 183
 184         _enter("");
 185
 186         if (list_empty(&trans->krxiodq_link)) {
 187                 spin_lock_irqsave(&rxrpc_krxiod_transportq_lock, flags);
 188
 189                 if (list_empty(&trans->krxiodq_link)) {
 190                         if (atomic_read(&trans->usage) > 0) {
 191                                 list_add_tail(&trans->krxiodq_link,
 192                                               &rxrpc_krxiod_transportq);
 193                                 atomic_inc(&rxrpc_krxiod_qcount);
 194                         }
 195                 }
 196
 197                 spin_unlock_irqrestore(&rxrpc_krxiod_transportq_lock, flags);
 198                 wake_up_all(&rxrpc_krxiod_sleepq);
 199         }
 200
 201         _leave("");
 202
 203 } /* end rxrpc_krxiod_queue_transport() */
 204
 205 /*****************************************************************************/
 206 /*
 207  * dequeue a transport from krxiod's attention queue
 208  */
 209 void rxrpc_krxiod_dequeue_transport(struct rxrpc_transport *trans)
 210 {
 211         unsigned long flags;
 212
 213         _enter("");
 214
 215         spin_lock_irqsave(&rxrpc_krxiod_transportq_lock, flags);
 216         if (!list_empty(&trans->krxiodq_link)) {
 217                 list_del_init(&trans->krxiodq_link);
 218                 atomic_dec(&rxrpc_krxiod_qcount);
 219         }
 220         spin_unlock_irqrestore(&rxrpc_krxiod_transportq_lock, flags);
 221
 222         _leave("");
 223
 224 } /* end rxrpc_krxiod_dequeue_transport() */
 225
 226 /*****************************************************************************/
 227 /*
 228  * queue a call for attention by krxiod
 229  */
 230 void rxrpc_krxiod_queue_call(struct rxrpc_call *call)
 231 {
 232         unsigned long flags;
 233
 234         if (list_empty(&call->rcv_krxiodq_lk)) {
 235                 spin_lock_irqsave(&rxrpc_krxiod_callq_lock, flags);
 236                 if (atomic_read(&call->usage) > 0) {
 237                         list_add_tail(&call->rcv_krxiodq_lk,
 238                                       &rxrpc_krxiod_callq);
 239                         atomic_inc(&rxrpc_krxiod_qcount);
 240                 }
 241                 spin_unlock_irqrestore(&rxrpc_krxiod_callq_lock, flags);
 242         }
 243         wake_up_all(&rxrpc_krxiod_sleepq);
 244
 245 } /* end rxrpc_krxiod_queue_call() */
 246
 247 /*****************************************************************************/
 248 /*
 249  * dequeue a call from krxiod's attention queue
 250  */
 251 void rxrpc_krxiod_dequeue_call(struct rxrpc_call *call)
 252 {
 253         unsigned long flags;
 254
 255         spin_lock_irqsave(&rxrpc_krxiod_callq_lock, flags);
 256         if (!list_empty(&call->rcv_krxiodq_lk)) {
 257                 list_del_init(&call->rcv_krxiodq_lk);
 258                 atomic_dec(&rxrpc_krxiod_qcount);
 259         }
 260         spin_unlock_irqrestore(&rxrpc_krxiod_callq_lock, flags);
 261
 262 } /* end rxrpc_krxiod_dequeue_call() */