curl: Check completion in curl_multi_do()

While it is more likely that transfers complete after some file
descriptor has data ready to read, we probably should not rely on it.
Better be safe than sorry and call curl_multi_check_completion() in
curl_multi_do(), too, just like it is done in curl_multi_read().

With this change, curl_multi_do() and curl_multi_read() are actually the
same, so drop curl_multi_read() and use curl_multi_do() as the sole FD
handler.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190910124136.10565-4-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit 948403b)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

block/curl.c

@@ -138,7 +138,6 @@ typedef struct BDRVCURLState {
 
 static void curl_clean_state(CURLState *s);
 static void curl_multi_do(void *arg);
-static void curl_multi_read(void *arg);
 
 #ifdef NEED_CURL_TIMER_CALLBACK
 /* Called from curl_multi_do_locked, with s->mutex held.  */
@@ -185,15 +184,15 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
     switch (action) {
         case CURL_POLL_IN:
             aio_set_fd_handler(s->aio_context, fd, false,
-                               curl_multi_read, NULL, NULL, state);
+                               curl_multi_do, NULL, NULL, state);
             break;
         case CURL_POLL_OUT:
             aio_set_fd_handler(s->aio_context, fd, false,
                                NULL, curl_multi_do, NULL, state);
             break;
         case CURL_POLL_INOUT:
             aio_set_fd_handler(s->aio_context, fd, false,
-                               curl_multi_read, curl_multi_do, NULL, state);
+                               curl_multi_do, curl_multi_do, NULL, state);
             break;
         case CURL_POLL_REMOVE:
             aio_set_fd_handler(s->aio_context, fd, false,
@@ -415,15 +414,6 @@ static void curl_multi_do(void *arg)
 {
     CURLState *s = (CURLState *)arg;
 
-    qemu_mutex_lock(&s->s->mutex);
-    curl_multi_do_locked(s);
-    qemu_mutex_unlock(&s->s->mutex);
-}
-
-static void curl_multi_read(void *arg)
-{
-    CURLState *s = (CURLState *)arg;
-
     qemu_mutex_lock(&s->s->mutex);
     curl_multi_do_locked(s);
     curl_multi_check_completion(s->s);