[27/55] curl: Report only ready sockets

Commit Message

Michael Roth Nov. 5, 2019, 8:52 p.m. UTC

From: Max Reitz <[e-mail]>

Instead of reporting all sockets to cURL, only report the one that has
caused curl_multi_do_locked() to be called.  This lets us get rid of the
QLIST_FOREACH_SAFE() list, which was actually wrong: SAFE foreaches are
only safe when the current element is removed in each iteration.  If it
possible for the list to be concurrently modified, we cannot guarantee
that only the current element will be removed.  Therefore, we must not
use QLIST_FOREACH_SAFE() here.

Fixes: ff5ca1664af85b24a4180d595ea6873fd3deac57
Cc: [e-mail]
Signed-off-by: Max Reitz <[e-mail]>
Message-id: [e-mail]
Reviewed-by: Maxim Levitsky <[e-mail]>
Reviewed-by: John Snow <[e-mail]>
Signed-off-by: Max Reitz <[e-mail]>
(cherry picked from commit 9abaf9fc474c3dd53e8e119326abc774c977c331)
Signed-off-by: Michael Roth <[e-mail]>
---
 block/curl.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

Patch

diff --git a/block/curl.c b/block/curl.c
index cf2686218d..fd70f1ebc4 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -392,24 +392,19 @@  static void curl_multi_check_completion(BDRVCURLState *s)
 }
 
 /* Called with s->mutex held.  */
-static void curl_multi_do_locked(CURLSocket *ready_socket)
+static void curl_multi_do_locked(CURLSocket *socket)
 {
-    CURLSocket *socket, *next_socket;
-    CURLState *s = ready_socket->state;
+    BDRVCURLState *s = socket->state->s;
     int running;
     int r;
 
-    if (!s->s->multi) {
+    if (!s->multi) {
         return;
     }
 
-    /* Need to use _SAFE because curl_multi_socket_action() may trigger
-     * curl_sock_cb() which might modify this list */
-    QLIST_FOREACH_SAFE(socket, &s->sockets, next, next_socket) {
-        do {
-            r = curl_multi_socket_action(s->s->multi, socket->fd, 0, &running);
-        } while (r == CURLM_CALL_MULTI_PERFORM);
-    }
+    do {
+        r = curl_multi_socket_action(s->multi, socket->fd, 0, &running);
+    } while (r == CURLM_CALL_MULTI_PERFORM);
 }
 
 static void curl_multi_do(void *arg)