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From: "iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libgcc/113401] Memory (resource) leak in -ftrampoline-impl=heap
Date: Mon, 22 Jan 2024 10:11:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113401

--- Comment #5 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Florian Weimer from comment #4)
> (In reply to Iain Sandoe from comment #3)
> > for platforms using pthreads as the underlying resource, then perhaps w=
e can
> > do this without thread_atexit (which I do not see in many places) by us=
ing
> > pthread_cleanup_push ()
>=20
> The current implementation already uses the same underlying mechanism as
> pthread_cleanup_push if building with -fexceptions. It does not solve the
> leak because the outermost handler deliberately does not perform a full
> deallocation of the thread state.

hmm.. I'm slightly confused here.

We certainly make the __gcc_nested_func_ptr_deleted () call a cleanup attac=
hed
to scope exits and certainly the last page of trampolines is not deallocated
(as you note for the sake of avoiding churn in m-mapping).

However, in the current code the only pthread-specific stuff I see (in, say
config/i386/heap-trampoline.c) is specific to changing protections on the
mapped pages.

What I was thinking of is attaching a thread exit cleanup using
pthread_cleanup_push() for platforms with pthreads but without Libc support=
 for
_thread_atexit - I guess I'm missing something :)=