From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8637CC433F5 for ; Sat, 19 Mar 2022 21:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238705AbiCSVo3 (ORCPT ); Sat, 19 Mar 2022 17:44:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234541AbiCSVo2 (ORCPT ); Sat, 19 Mar 2022 17:44:28 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A286184ECA for ; Sat, 19 Mar 2022 14:43:05 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id v4so10153278pjh.2 for ; Sat, 19 Mar 2022 14:43:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=UqtV0sA6am1PG8OrsaZwoVNFPOXqg06kiugHXJNvLeQ=; b=WU18js+rK16bib1QhvI03yI7kYULUGMKW9nv1dI9eXfe2mluLPgIirzeDjUJ4XlT2y yNr67a+T3sd/sXFTOfEpg7+OVQxSEeX6fh6FU97KR7IOleY2ejNVIjf3LmgifB0RyVSJ RLzN05a1+wgbQNtUq6AAvuDR8CZ6K4xCVaLaLrnjd96XdW95M6SOQOslFv1XN2tvPHMR ZfC6/tc7k5pbi54zaceULNs6c0g0s4jw10QaWu0H1tXjJrBfS5twU/wkXsz5I3YeCMSZ /0ZR1LvM5Il+y1dikf+6nODUNqfK/zN7J0Q8SoDlu6Vrn5b9+/iRRxdEh72jp+Y/gWCA 9Ulw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=UqtV0sA6am1PG8OrsaZwoVNFPOXqg06kiugHXJNvLeQ=; b=SePbR9REZCCN+PNjwOproZy1OcQ2GHviR1v7xG6EmfQGoy++uzTbvXNeMhKo8g1iWa aJ/JpbyLPBD0HSFIJ2mTGQ9po1P4s7OlCDU9yYH4pv2hOOYVnV92bOOSWruicrRc6oAS JUIYia2k1zxEwse5WLVpQI4L2NmGFlOs4e6LWjvhNseBFFkDWvy/DPbDyz3ye7a9Wf1X FCbRO4BCqVazIHdCzwbVAh+Bi75b/P+fW9/UoV0nln+e10YgGB8sKUcp2CoBXQhRSK3m r22FrvdEdyhL3uiHosSU8/fW66ZNG6YJeicsUu5ZQSskOAjveNlIMkmGyOCnvTwWhXHM EbdA== X-Gm-Message-State: AOAM530J9W04U9F4HQA+FYndv+3BOl6uQ8Lw0tvpgVWTxBq1r90sbsGZ pFuzzhRDRobCTUJGPhCdEfc= X-Google-Smtp-Source: ABdhPJy+QsHGjhQJmyVYaQGH6fnXI2vB/fqpMUaEdJ70K9M1mxqOrV9EVS8I4pWL8590mgRNiILz+w== X-Received: by 2002:a17:902:a40d:b0:153:7213:1584 with SMTP id p13-20020a170902a40d00b0015372131584mr5818730plq.56.1647726185188; Sat, 19 Mar 2022 14:43:05 -0700 (PDT) Received: from localhost ([14.139.187.71]) by smtp.gmail.com with ESMTPSA id s12-20020a056a00194c00b004f7c1da7dd5sm14236222pfk.1.2022.03.19.14.43.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Mar 2022 14:43:04 -0700 (PDT) Date: Sun, 20 Mar 2022 03:13:03 +0530 From: Kumar Kartikeya Dwivedi To: Alexei Starovoitov Cc: bpf@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= , Jesper Dangaard Brouer Subject: Re: [PATCH bpf-next v2 04/15] bpf: Allow storing referenced kptr in map Message-ID: <20220319214303.n3aogzbz3fjaohcy@apollo> References: <20220317115957.3193097-1-memxor@gmail.com> <20220317115957.3193097-5-memxor@gmail.com> <20220319182407.amdeiliph36zdwlg@ast-mbp.dhcp.thefacebook.com> <20220319185904.dq5h6tnspwx77dze@apollo> <20220319212320.oos7tao6mybsjt6i@ast-mbp.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220319212320.oos7tao6mybsjt6i@ast-mbp.dhcp.thefacebook.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Sun, Mar 20, 2022 at 02:53:20AM IST, Alexei Starovoitov wrote: > On Sun, Mar 20, 2022 at 12:29:04AM +0530, Kumar Kartikeya Dwivedi wrote: > > > > > > > > if (is_release_function(func_id)) { > > > > - err = release_reference(env, meta.ref_obj_id); > > > > + err = -EINVAL; > > > > + if (meta.ref_obj_id) > > > > + err = release_reference(env, meta.ref_obj_id); > > > > + /* Only bpf_kptr_xchg is a release function that accepts a > > > > + * possibly NULL reg, hence meta.ref_obj_id can only be unset > > > > + * for it. > > > > > > Could you rephrase the comment? I'm not following what it's trying to convey. > > > > > > > All existing release helpers never take a NULL register, so their > > meta.ref_obj_id will never be unset, but bpf_kptr_xchg can, so it needs some > > special handling. In check_func_arg, when it jumps to skip_type_check label, > > reg->ref_obj_id won't be set for NULL value. > > I still don't follow. > What do you mean 'unset meta.ref_obj_id' ? > It's either set or not. By unset I meant it is the default (0). > meta->ref_obj_id will stay zero when arg == NULL. > Above 'if (meta.ref_obj_id)' makes sense. > But the code below with extra func_id check looks like defensive programming again. > Ok, so I'll just write it like: if (is_release_function(...) && meta.ref_obj_id) { err = release_reference(...); if (err) ... } > > > > + */ > > > > + else if (func_id == BPF_FUNC_kptr_xchg) > > > > + err = 0; -- Kartikeya