From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 3FA87389EC5B; Fri,  7 Oct 2022 13:49:26 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3FA87389EC5B
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1665150566;
	bh=h8ZpZWyfys44HAiE7MYyelvnfMbPi7j9EiqjiyxUFiA=;
	h=From:To:Subject:Date:From;
	b=NemA6GvWgXqRV2MkaW1skvs08awGF2aQ5rAzAmmPvS0wjLt5MMjuc4H69zDVKFyad
	 fgod6y0EIAlGYy7oRLL/kXPL7xp7f1Xqd7HWRJkfKH+xdW3+Lir/z0Veis12eu7Mnm
	 Pt6EJUgD6XlUTVcX81KJHmdt7pX+8PGh++d00Ejc=
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/107180] New: Itanium ABI says to block in the
 emergency EH buffer if memory cannot be acquired
Date: Fri, 07 Oct 2022 13:49:25 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-107180-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107180

            Bug ID: 107180
           Summary: Itanium ABI says to block in the emergency EH buffer
                    if memory cannot be acquired
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html#imp-emergency says:

"Additional threads are blocked until one of the 16 de-allocates its emerge=
ncy
buffer storage."

Ignoring the fact that we don't limit the number of threads that can use the
buffer concurrently, our __cxa_allocate_exception first tries malloc, then
tries the emergency pool, then terminates. We should add a condition_variab=
le
to the pool and block when it's full.

This needs to be optional though. For some users blocking indefinitely is w=
orse
than terminating. Maybe use a tunable.=