curl: Pass CURLSocket to curl_multi_do()

curl_multi_do_locked() currently marks all sockets as ready.  That is
not only inefficient, but in fact unsafe (the loop is).  A follow-up
patch will change that, but to do so, curl_multi_do_locked() needs to
know exactly which socket is ready; and that is accomplished by this
patch here.

Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190910124136.10565-5-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 9dbad87)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

block/curl.c

@@ -184,15 +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_do, NULL, NULL, state);
+                               curl_multi_do, NULL, NULL, socket);
             break;
         case CURL_POLL_OUT:
             aio_set_fd_handler(s->aio_context, fd, false,
-                               NULL, curl_multi_do, NULL, state);
+                               NULL, curl_multi_do, NULL, socket);
             break;
         case CURL_POLL_INOUT:
             aio_set_fd_handler(s->aio_context, fd, false,
-                               curl_multi_do, curl_multi_do, NULL, state);
+                               curl_multi_do, curl_multi_do, NULL, socket);
             break;
         case CURL_POLL_REMOVE:
             aio_set_fd_handler(s->aio_context, fd, false,
@@ -391,9 +391,10 @@ static void curl_multi_check_completion(BDRVCURLState *s)
 }
 
 /* Called with s->mutex held.  */
-static void curl_multi_do_locked(CURLState *s)
+static void curl_multi_do_locked(CURLSocket *ready_socket)
 {
     CURLSocket *socket, *next_socket;
+    CURLState *s = ready_socket->state;
     int running;
     int r;
 
@@ -412,12 +413,13 @@ static void curl_multi_do_locked(CURLState *s)
 
 static void curl_multi_do(void *arg)
 {
-    CURLState *s = (CURLState *)arg;
+    CURLSocket *socket = arg;
+    BDRVCURLState *s = socket->state->s;
 
-    qemu_mutex_lock(&s->s->mutex);
-    curl_multi_do_locked(s);
-    curl_multi_check_completion(s->s);
-    qemu_mutex_unlock(&s->s->mutex);
+    qemu_mutex_lock(&s->mutex);
+    curl_multi_do_locked(socket);
+    curl_multi_check_completion(s);
+    qemu_mutex_unlock(&s->mutex);
 }
 
 static void curl_multi_timeout_do(void *arg)