From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.6 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id BA583202A5 for ; Sat, 23 Sep 2017 03:47:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751880AbdIWDrU (ORCPT ); Fri, 22 Sep 2017 23:47:20 -0400 Received: from cloud.peff.net ([104.130.231.41]:47750 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751832AbdIWDrT (ORCPT ); Fri, 22 Sep 2017 23:47:19 -0400 Received: (qmail 21886 invoked by uid 109); 23 Sep 2017 03:47:20 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Sat, 23 Sep 2017 03:47:20 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 10587 invoked by uid 111); 23 Sep 2017 03:47:57 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with SMTP; Fri, 22 Sep 2017 23:47:57 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 22 Sep 2017 23:47:17 -0400 Date: Fri, 22 Sep 2017 23:47:17 -0400 From: Jeff King To: Martin =?utf-8?B?w4VncmVu?= Cc: git@vger.kernel.org Subject: Re: [PATCH v2 3/6] leak_pending: use `object_array_clear()`, not `free()` Message-ID: <20170923034717.i65irpbmlxtzwo3h@sigill.intra.peff.net> References: <20170920200229.bc4yniz6otng2zyz@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sat, Sep 23, 2017 at 01:34:51AM +0200, Martin Ågren wrote: > Setting `leak_pending = 1` tells `prepare_revision_walk()` not to > release the `pending` array, and makes that the caller's responsibility. > See 4a43d374f (revision: add leak_pending flag, 2011-10-01) and > 353f5657a (bisect: use leak_pending flag, 2011-10-01). > > Commit 1da1e07c8 (clean up name allocation in prepare_revision_walk, > 2014-10-15) fixed a memory leak in `prepare_revision_walk()` by > switching from `free()` to `object_array_clear()`. However, where we use > the `leak_pending`-mechanism, we're still only calling `free()`. Thanks for digging up the history here. Reviewing those it seems clear that doing a full object_array_clear() is the right thing. > Use `object_array_clear()` instead. Copy some helpful comments from > 353f5657a to the other callers that we update to clarify the memory > responsibilities, and to highlight that the commits are not affected > when we clear the array -- it is indeed correct to both tidy up the > commit flags and clear the object array. > > Document `leak_pending` in revision.h to help future users get this > right. This all looks good to me. Since the main use of "leak_pending" seems to be to clear commit marks, I have a feeling that a better API would have been something like: /* normal setup and use */ init_revisions(&rev); setup_revisions(&rev, ...); prepare_revision_walk(&rev); while (get_revision(&rev)) ...; /* optional, but sensible if there may be other callers */ clear_commit_marks(&rev); /* actually free any held memory */ clear_revisions(&rev); which would imply rev_info holding onto the "old" pending list automatically until we decommission the rev_info in the final step. But that's obviously a much bigger change. What you have here looks like a nice clean fix to the leak problems. -Peff