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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug gdb/29311] [gdb] ThreadSanitizer: data race
 (/lib64/libtsan.so.2+0x4c5e2) in free
Date: Wed, 13 Jul 2022 10:58:33 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D29311

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #3)
> (In reply to Tom de Vries from comment #2)
> > So, is this a problem with=20
> order of destroying things?
>=20
> First the threads need to be destroyed, before objects that may have been
> used by those threads?

Hmm, in a way it could be.

There's a static vector, which is written by the main thread at initializat=
ion
time, then read by various threads, and destroyed upon exit by the main thr=
ead.

We don't wait on pending tasks before exit, so some of those could still be
running and accessing the vector, or rather, what it points to.

This stops us from xfreeing the strings contained in the vector:
...
diff --git a/gdb/charset.c b/gdb/charset.c
index 74f742e0aa7..e9d28fcb1b1 100644
--- a/gdb/charset.c
+++ b/gdb/charset.c
@@ -694,7 +694,7 @@ struct charset_vector
 {
   ~charset_vector ()
   {
-    clear ();
+    charsets.clear ();
   }

   void clear ()
...
and that fixes the race condition from comment 2.

--=20
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