From ff5091aa9f73802e894b1cbdf24ab84e103200e2 Mon Sep 17 00:00:00 2001
From: Andy Pan <i@andypan.me>
Date: Thu, 12 Dec 2024 12:48:56 +0000
Subject: [PATCH] async-thread: avoid closing eventfd twice

When employing eventfd for socketpair, there is only one file
descriptor. Closing that fd twice might result in fd corruption.
Thus, we should avoid closing the eventfd twice, following the
pattern in lib/multi.c.

Fixes #15725
Closes #15727
Reported-by: Christian Heusel
---
 lib/asyn-thread.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/asyn-thread.c b/lib/asyn-thread.c
index a58e4b79049..32d496b107c 100644
--- a/lib/asyn-thread.c
+++ b/lib/asyn-thread.c
@@ -195,9 +195,11 @@ void destroy_thread_sync_data(struct thread_sync_data *tsd)
    * close one end of the socket pair (may be done in resolver thread);
    * the other end (for reading) is always closed in the parent thread.
    */
+#ifndef USE_EVENTFD
   if(tsd->sock_pair[1] != CURL_SOCKET_BAD) {
     wakeup_close(tsd->sock_pair[1]);
   }
+#endif
 #endif
   memset(tsd, 0, sizeof(*tsd));
 }
