From: Eli Zaretskii <eliz@gnu.org>
Date: Thu, 3 Jul 2025 13:19:09 +0000 (+0300)
Subject: Avoid segfaults due to C-g when a thread does GC
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=ccc0fa28a846bbc9123004d6c38fdae2bfc2bec4;p=emacs.git

Avoid segfaults due to C-g when a thread does GC

* src/keyboard.c (handle_interrupt): Don't forcibly switch threads
if a non-main thread was in GC when the signal handler was called.

(cherry picked from commit 205d69e7e64cf23df0bc7a52b1149f6130c117b5)
---

diff --git a/src/keyboard.c b/src/keyboard.c
index d7f15aeb4e1..fa0a5fbdd1a 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -12350,7 +12350,15 @@ handle_interrupt (bool in_signal_handler)
      thread, see deliver_process_signal.  So we must make sure the
      main thread holds the global lock.  */
   if (in_signal_handler)
-    maybe_reacquire_global_lock ();
+    {
+      /* But if the signal handler was called when a non-main thread was
+         in GC, just return, since switching threads by force-taking the
+         global lock will confuse the heck out of GC, and will most
+         likely segfault.  */
+      if (!main_thread_p (current_thread) && gc_in_progress)
+	return;
+      maybe_reacquire_global_lock ();
+    }
 #endif
   if (waiting_for_input && !echoing)
     quit_throw_to_read_char (in_signal_handler);