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 X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DDCFC10DCE for ; Thu, 12 Mar 2020 23:23:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A0F520637 for ; Thu, 12 Mar 2020 23:23:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726788AbgCLXXC (ORCPT ); Thu, 12 Mar 2020 19:23:02 -0400 Received: from www62.your-server.de ([213.133.104.62]:41302 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726710AbgCLXXC (ORCPT ); Thu, 12 Mar 2020 19:23:02 -0400 Received: from sslproxy06.your-server.de ([78.46.172.3]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1jCXAJ-0000L5-LW; Fri, 13 Mar 2020 00:22:59 +0100 Received: from [85.7.42.192] (helo=pc-9.home) by sslproxy06.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jCXAJ-0000eZ-CO; Fri, 13 Mar 2020 00:22:59 +0100 Subject: Re: [PATCH bpf-next] bpf: abstract away entire bpf_link clean up procedure To: Andrii Nakryiko , bpf@vger.kernel.org, netdev@vger.kernel.org, ast@fb.com Cc: andrii.nakryiko@gmail.com, kernel-team@fb.com References: <20200312203914.1195762-1-andriin@fb.com> From: Daniel Borkmann Message-ID: <2d6ae192-fe22-0239-54c7-142ec21b7794@iogearbox.net> Date: Fri, 13 Mar 2020 00:22:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20200312203914.1195762-1-andriin@fb.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.2/25749/Thu Mar 12 14:09:06 2020) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 3/12/20 9:39 PM, Andrii Nakryiko wrote: > Instead of requiring users to do three steps for cleaning up bpf_link, its > anon_inode file, and unused fd, abstract that away into bpf_link_cleanup() > helper. bpf_link_defunct() is removed, as it shouldn't be needed as an > individual operation anymore. > > Signed-off-by: Andrii Nakryiko > --- > include/linux/bpf.h | 3 ++- > kernel/bpf/syscall.c | 18 +++++++++++------- > 2 files changed, 13 insertions(+), 8 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 4fd91b7c95ea..358f3eb07c01 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -1075,7 +1075,8 @@ struct bpf_link_ops { > > void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops, > struct bpf_prog *prog); > -void bpf_link_defunct(struct bpf_link *link); > +void bpf_link_cleanup(struct bpf_link *link, struct file *link_file, > + int link_fd); > void bpf_link_inc(struct bpf_link *link); > void bpf_link_put(struct bpf_link *link); > int bpf_link_new_fd(struct bpf_link *link); > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index b2f73ecacced..d2f49ae225b0 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -2188,9 +2188,17 @@ void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops, > link->prog = prog; > } > > -void bpf_link_defunct(struct bpf_link *link) > +/* Clean up bpf_link and corresponding anon_inode file and FD. After > + * anon_inode is created, bpf_link can't be just kfree()'d due to deferred > + * anon_inode's release() call. This helper manages marking bpf_link as > + * defunct, releases anon_inode file and puts reserved FD. > + */ > +void bpf_link_cleanup(struct bpf_link *link, struct file *link_file, > + int link_fd) Looks good, but given it is only used here this should be static instead. > { > link->prog = NULL; > + fput(link_file); > + put_unused_fd(link_fd); > } > > void bpf_link_inc(struct bpf_link *link) > @@ -2383,9 +2391,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog) > > err = bpf_trampoline_link_prog(prog); > if (err) { > - bpf_link_defunct(&link->link); > - fput(link_file); > - put_unused_fd(link_fd); > + bpf_link_cleanup(&link->link, link_file, link_fd); > goto out_put_prog; > } > > @@ -2498,9 +2504,7 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr) > > err = bpf_probe_register(link->btp, prog); > if (err) { > - bpf_link_defunct(&link->link); > - fput(link_file); > - put_unused_fd(link_fd); > + bpf_link_cleanup(&link->link, link_file, link_fd); > goto out_put_btp; > } > >