From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Maxime Devos Newsgroups: gmane.lisp.guile.devel Subject: Re: GC + Java finalization Date: Fri, 19 Nov 2021 13:44:54 +0000 Message-ID: <43a9f555dec7ddeee1ad34c278042a6bad6c59ec.camel@telenet.be> References: <9ce77d5e08d50456eddc575179b68ac17afc9bf6.camel@hahnjo.de> <1cc3648e5196bf23023ec7a0ab95a9ad46f8554c.camel@telenet.be> <21fe294b75b001afbd1be0e972a19ddb7187e98b.camel@hahnjo.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="23111"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Evolution 3.38.3-1 To: Jonas Hahnfeld , guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane-mx.org@gnu.org Fri Nov 19 14:48:20 2021 Return-path: Envelope-to: guile-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mo4FX-0005kZ-L4 for guile-devel@m.gmane-mx.org; Fri, 19 Nov 2021 14:48:19 +0100 Original-Received: from localhost ([::1]:50022 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mo4FW-0002l4-FF for guile-devel@m.gmane-mx.org; Fri, 19 Nov 2021 08:48:18 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:59168) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mo4CJ-00072x-BG for guile-devel@gnu.org; Fri, 19 Nov 2021 08:44:59 -0500 Original-Received: from [2a02:1800:120:4::f00:15] (port=45698 helo=andre.telenet-ops.be) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mo4CH-00073X-0N for guile-devel@gnu.org; Fri, 19 Nov 2021 08:44:59 -0500 Original-Received: from ptr-bvsjgyhxw7psv60dyze.18120a2.ip6.access.telenet.be ([IPv6:2a02:1811:8c09:9d00:3c5f:2eff:feb0:ba5a]) by andre.telenet-ops.be with bizsmtp id LDku2600A4UW6Th01Dkuyp; Fri, 19 Nov 2021 14:44:54 +0100 In-Reply-To: <21fe294b75b001afbd1be0e972a19ddb7187e98b.camel@hahnjo.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=telenet.be; s=r21; t=1637329494; bh=H4g9f/j/EbSgNWOI4Uwgkli9/fu9MgUmbrHHXvyyM4U=; h=Subject:From:To:Date:In-Reply-To:References; b=mEfnEJKZe94lNKnFDZ5xdFLxEFYnsAZdY57PwJpIWQJmo9aw19YcK7yBiMhGNxb3u HXApl/MY38GK3EztBEZEj+EBscOEVo4UN2sE2MqiQ4NscJ8GwtjC8ZeaXA2kuVf5F2 jMbWT22Q6Yx65/9DZ3hzP8DbS29dt6yxGtaAIENXu4FSrqaZ3aMuWL+1Obe0382XSb l22biM7x9UBLhu0a8zXqAGz8GmhrosMEAH9OrBENnOv2qDyiMGpDkaOm57swjTmnFZ KTBxHkQVXvvWINzlt6dHcPXtXOjOrY1BypV4I6la53r+QSBgVjr120f1peyULwwoHQ fQNvIHEq+9Q7Q== X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a02:1800:120:4::f00:15 (failed) Received-SPF: pass client-ip=2a02:1800:120:4::f00:15; envelope-from=maximedevos@telenet.be; helo=andre.telenet-ops.be X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_LOW=-0.7, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-devel-bounces+guile-devel=m.gmane-mx.org@gnu.org Original-Sender: "guile-devel" Xref: news.gmane.io gmane.lisp.guile.devel:20964 Archived-At: Jonas Hahnfeld schreef op vr 19-11-2021 om 14:40 [+0100]: > Am Freitag, dem 19.11.2021 um 13:35 +0000 schrieb Maxime Devos: > > Jonas Hahnfeld schreef op vr 19-11-2021 om 14:32 [+0100]: > > > > You coud simply ... > > > > > > > > > > > > > -      scm_gc_free (rx, sizeof(regex_t), "regex"); > > > > > +      free (rx); > > > > > > > > drop the scm_gc_free AFAIK. > > > > > > No, I cannot as explained in the patch summary: If we use > > > scm_gc_free > > > in a free function of a Smob, this relies on Java finalization > > > because > > > the memory must not be reclaimed in the same cycle. > > > > The suggestion was to remove scm_gc_free, and not introduce free. > > I.e., don't free rx manually at all, let boehmgc decide: > > > >  regex_free (SCM obj) > >  { > >    regfree (SCM_RGX (obj)); > > -  scm_gc_free (SCM_RGX (obj), sizeof(regex_t), "regex"); > >    return 0; > >  } > > This is dangerous because we still pass the memory to regfree, so it > must not be freed before. How can removing a call to a free function introduce new use-after-free bugs or double-free bugs? AFAIK, ignoring memory leak concerns (which don't seem to apply here because of boehmgc), freeing less stuff cannot introduce new bugs. Greetings, Maxime