qemu-coroutine.c

   1 /*
   2  * QEMU coroutines
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
   8  *  Kevin Wolf         <kwolf@redhat.com>
   9  *
  10  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  11  * See the COPYING.LIB file in the top-level directory.
  12  *
  13  */
  14
  15 #include "trace.h"
  16 #include "qemu-common.h"
  17 #include "block/coroutine.h"
  18 #include "block/coroutine_int.h"
  19
  20 Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
  21 {
  22     Coroutine *co = qemu_coroutine_new();
  23     co->entry = entry;
  24     return co;
  25 }
  26
  27 static void coroutine_swap(Coroutine *from, Coroutine *to)
  28 {
  29     CoroutineAction ret;
  30
  31     ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
  32
  33     switch (ret) {
  34     case COROUTINE_YIELD:
  35         return;
  36     case COROUTINE_TERMINATE:
  37         trace_qemu_coroutine_terminate(to);
  38         qemu_coroutine_delete(to);
  39         return;
  40     default:
  41         abort();
  42     }
  43 }
  44
  45 void qemu_coroutine_enter(Coroutine *co, void *opaque)
  46 {
  47     Coroutine *self = qemu_coroutine_self();
  48
  49     trace_qemu_coroutine_enter(self, co, opaque);
  50
  51     if (co->caller) {
  52         fprintf(stderr, "Co-routine re-entered recursively\n");
  53         abort();
  54     }
  55
  56     co->caller = self;
  57     co->entry_arg = opaque;
  58     coroutine_swap(self, co);
  59 }
  60
  61 void coroutine_fn qemu_coroutine_yield(void)
  62 {
  63     Coroutine *self = qemu_coroutine_self();
  64     Coroutine *to = self->caller;
  65
  66     trace_qemu_coroutine_yield(self, to);
  67
  68     if (!to) {
  69         fprintf(stderr, "Co-routine is yielding to no one\n");
  70         abort();
  71     }
  72
  73     self->caller = NULL;
  74     coroutine_swap(self, to);
  75 }