curl: convert to CoQueue

Now that CoQueues can use a QemuMutex for thread-safety, there is no
need for curl to roll its own coroutine queue.  Coroutines can be
placed directly on the queue instead of using a list of CURLAIOCBs.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20180203153935.8056-6-pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

block/curl.c

@@ -101,8 +101,6 @@ typedef struct CURLAIOCB {
 
     size_t start;
     size_t end;
-
-    QSIMPLEQ_ENTRY(CURLAIOCB) next;
 } CURLAIOCB;
 
 typedef struct CURLSocket {
@@ -138,7 +136,7 @@ typedef struct BDRVCURLState {
     bool accept_range;
     AioContext *aio_context;
     QemuMutex mutex;
-    QSIMPLEQ_HEAD(, CURLAIOCB) free_state_waitq;
+    CoQueue free_state_waitq;
     char *username;
     char *password;
     char *proxyusername;
@@ -538,7 +536,6 @@ static int curl_init_state(BDRVCURLState *s, CURLState *state)
 /* Called with s->mutex held.  */
 static void curl_clean_state(CURLState *s)
 {
-    CURLAIOCB *next;
     int j;
     for (j = 0; j < CURL_NUM_ACB; j++) {
         assert(!s->acb[j]);
@@ -556,13 +553,7 @@ static void curl_clean_state(CURLState *s)
 
     s->in_use = 0;
 
-    next = QSIMPLEQ_FIRST(&s->s->free_state_waitq);
-    if (next) {
-        QSIMPLEQ_REMOVE_HEAD(&s->s->free_state_waitq, next);
-        qemu_mutex_unlock(&s->s->mutex);
-        aio_co_wake(next->co);
-        qemu_mutex_lock(&s->s->mutex);
-    }
+    qemu_co_enter_next(&s->s->free_state_waitq, &s->s->mutex);
 }
 
 static void curl_parse_filename(const char *filename, QDict *options,
@@ -784,7 +775,7 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     DPRINTF("CURL: Opening %s\n", file);
-    QSIMPLEQ_INIT(&s->free_state_waitq);
+    qemu_co_queue_init(&s->free_state_waitq);
     s->aio_context = bdrv_get_aio_context(bs);
     s->url = g_strdup(file);
     qemu_mutex_lock(&s->mutex);
@@ -888,10 +879,7 @@ static void curl_setup_preadv(BlockDriverState *bs, CURLAIOCB *acb)
         if (state) {
             break;
         }
-        QSIMPLEQ_INSERT_TAIL(&s->free_state_waitq, acb, next);
-        qemu_mutex_unlock(&s->mutex);
-        qemu_coroutine_yield();
-        qemu_mutex_lock(&s->mutex);
+        qemu_co_queue_wait(&s->free_state_waitq, &s->mutex);
     }
 
     if (curl_init_state(s, state) < 0) {