global_init: move the IPv6 works status bool to multi handle

Previously it was stored in a global state which contributed to
curl_global_init's thread unsafety. This boolean is now instead figured
out in curl_multi_init() and stored in the multi handle. Less effective,
but thread safe.

Closes #4851

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/multihandle.h b/lib/multihandle.h
index b0cd0b821..91eca16c4 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -119,11 +119,6 @@ struct Curl_multi {
      same actual socket) */
   struct curl_hash sockhash;
 
-  /* multiplexing wanted */
-  bool multiplexing;
-
-  bool recheckstate; /* see Curl_multi_connchanged */
-
   /* Shared connection cache (bundles)*/
   struct conncache conn_cache;
 
@@ -141,13 +136,17 @@ struct Curl_multi {
   void *timer_userp;
   struct curltime timer_lastcall; /* the fixed time for the timeout for the
                                     previous callback */
-  bool in_callback;            /* true while executing a callback */
   unsigned int max_concurrent_streams;
 
 #ifdef ENABLE_WAKEUP
   curl_socket_t wakeup_pair[2]; /* socketpair() used for wakeup
                                    0 is used for read, 1 is used for write */
 #endif
+  /* multiplexing wanted */
+  bool multiplexing;
+  bool recheckstate; /* see Curl_multi_connchanged */
+  bool in_callback;            /* true while executing a callback */
+  bool ipv6_works;
 };
 
 #endif /* HEADER_CURL_MULTIHANDLE_H */