File:  [Qemu by Fabrice Bellard] / qemu / async.c
Revision 1.1.1.3 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 19:17:54 2018 UTC (3 years, 1 month ago) by root
Branches: qemu, MAIN
CVS tags: qemu1001, HEAD
qemu 1.0.1

    1: /*
    2:  * QEMU System Emulator
    3:  *
    4:  * Copyright (c) 2003-2008 Fabrice Bellard
    5:  *
    6:  * Permission is hereby granted, free of charge, to any person obtaining a copy
    7:  * of this software and associated documentation files (the "Software"), to deal
    8:  * in the Software without restriction, including without limitation the rights
    9:  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   10:  * copies of the Software, and to permit persons to whom the Software is
   11:  * furnished to do so, subject to the following conditions:
   12:  *
   13:  * The above copyright notice and this permission notice shall be included in
   14:  * all copies or substantial portions of the Software.
   15:  *
   16:  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   17:  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   18:  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   19:  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   20:  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   21:  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   22:  * THE SOFTWARE.
   23:  */
   24: 
   25: #include "qemu-common.h"
   26: #include "qemu-aio.h"
   27: #include "main-loop.h"
   28: 
   29: /* Anchor of the list of Bottom Halves belonging to the context */
   30: static struct QEMUBH *first_bh;
   31: 
   32: /***********************************************************/
   33: /* bottom halves (can be seen as timers which expire ASAP) */
   34: 
   35: struct QEMUBH {
   36:     QEMUBHFunc *cb;
   37:     void *opaque;
   38:     int scheduled;
   39:     int idle;
   40:     int deleted;
   41:     QEMUBH *next;
   42: };
   43: 
   44: QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
   45: {
   46:     QEMUBH *bh;
   47:     bh = g_malloc0(sizeof(QEMUBH));
   48:     bh->cb = cb;
   49:     bh->opaque = opaque;
   50:     bh->next = first_bh;
   51:     first_bh = bh;
   52:     return bh;
   53: }
   54: 
   55: int qemu_bh_poll(void)
   56: {
   57:     QEMUBH *bh, **bhp, *next;
   58:     int ret;
   59:     static int nesting = 0;
   60: 
   61:     nesting++;
   62: 
   63:     ret = 0;
   64:     for (bh = first_bh; bh; bh = next) {
   65:         next = bh->next;
   66:         if (!bh->deleted && bh->scheduled) {
   67:             bh->scheduled = 0;
   68:             if (!bh->idle)
   69:                 ret = 1;
   70:             bh->idle = 0;
   71:             bh->cb(bh->opaque);
   72:         }
   73:     }
   74: 
   75:     nesting--;
   76: 
   77:     /* remove deleted bhs */
   78:     if (!nesting) {
   79:         bhp = &first_bh;
   80:         while (*bhp) {
   81:             bh = *bhp;
   82:             if (bh->deleted) {
   83:                 *bhp = bh->next;
   84:                 g_free(bh);
   85:             } else {
   86:                 bhp = &bh->next;
   87:             }
   88:         }
   89:     }
   90: 
   91:     return ret;
   92: }
   93: 
   94: void qemu_bh_schedule_idle(QEMUBH *bh)
   95: {
   96:     if (bh->scheduled)
   97:         return;
   98:     bh->scheduled = 1;
   99:     bh->idle = 1;
  100: }
  101: 
  102: void qemu_bh_schedule(QEMUBH *bh)
  103: {
  104:     if (bh->scheduled)
  105:         return;
  106:     bh->scheduled = 1;
  107:     bh->idle = 0;
  108:     /* stop the currently executing CPU to execute the BH ASAP */
  109:     qemu_notify_event();
  110: }
  111: 
  112: void qemu_bh_cancel(QEMUBH *bh)
  113: {
  114:     bh->scheduled = 0;
  115: }
  116: 
  117: void qemu_bh_delete(QEMUBH *bh)
  118: {
  119:     bh->scheduled = 0;
  120:     bh->deleted = 1;
  121: }
  122: 
  123: void qemu_bh_update_timeout(int *timeout)
  124: {
  125:     QEMUBH *bh;
  126: 
  127:     for (bh = first_bh; bh; bh = bh->next) {
  128:         if (!bh->deleted && bh->scheduled) {
  129:             if (bh->idle) {
  130:                 /* idle bottom halves will be polled at least
  131:                  * every 10ms */
  132:                 *timeout = MIN(10, *timeout);
  133:             } else {
  134:                 /* non-idle bottom halves will be executed
  135:                  * immediately */
  136:                 *timeout = 0;
  137:                 break;
  138:             }
  139:         }
  140:     }
  141: }
  142: 

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