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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 6B4EDC433E0 for ; Tue, 23 Jun 2020 20:59:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4031420656 for ; Tue, 23 Jun 2020 20:59:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="m+WSj3bt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391041AbgFWU7n (ORCPT ); Tue, 23 Jun 2020 16:59:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390114AbgFWU7l (ORCPT ); Tue, 23 Jun 2020 16:59:41 -0400 Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECD95C061573 for ; Tue, 23 Jun 2020 13:59:40 -0700 (PDT) Received: by mail-lj1-x242.google.com with SMTP id 9so94300ljc.8 for ; Tue, 23 Jun 2020 13:59:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=TT2FZxgpjI3VkckydSkMTZ86IbhbF6gKg3r0vREiuvk=; b=m+WSj3btBtZQ/D6lseNcykWUPiFeFygNNYhSssoKxz+FopYF+OQrtacfrQKI7odjvK GvvCY2sAIPaL2PqhZBWLCdHEcWN0UxRSMRQ9GLAgKuNMgqflcjNgQNe4dXmz6LP2HOmG v0S/jglF4lP8Pp5PTd4K/PmrhQxhWF8yhGJy4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=TT2FZxgpjI3VkckydSkMTZ86IbhbF6gKg3r0vREiuvk=; b=MuKpl8GfqoybR194JC6Q1hnx9mT8Axn0FUhT1repTaivRvLWVhaaz4MGQaJazrG7Ba j7eJ9r1Wu3lzr9wGu3CVmy5+/pRA51UBXRK+nQRhPAfa2ndUlejAkAxAKBbYy+wVirvT 25BA6iYiqOsR5eilLcySKIZ0Fv8fgFs/0OBTiahtrPt76+5lzoUqTrryH3twLdI7kmrY Gm0lyNuOh9SvoepqVOpgWetC6fsbJFmcO4GvIEWrecYuQ62EWKXl8NtmnTxcRSYpWYk0 5huJ0pRxSukztrs+RQkW1m4hI/fc3CnwJIl6tvFpFciCpSoJgvh3GKSXAwfXQo/jlclc t9Eg== X-Gm-Message-State: AOAM533QUnOniLJpADBnnVJig8Y8n5OzfaFStzk4AtC0XDMUXaA7NASI V4SFpBhj2ReqBDoHmZaKPjBC3g== X-Google-Smtp-Source: ABdhPJzVM7jBvlMi/1dIDGHjpIwo7Vb0q67nlm85VQ9OwQDLnc5UYl+TRxakJLLS1YEM9e+jS1BCZg== X-Received: by 2002:a05:651c:544:: with SMTP id q4mr12640870ljp.310.1592945979425; Tue, 23 Jun 2020 13:59:39 -0700 (PDT) Received: from cloudflare.com ([2a02:a310:c262:aa00:b35e:8938:2c2a:ba8b]) by smtp.gmail.com with ESMTPSA id r15sm3518864ljm.31.2020.06.23.13.59.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jun 2020 13:59:38 -0700 (PDT) References: <20200623103459.697774-1-jakub@cloudflare.com> <20200623103459.697774-3-jakub@cloudflare.com> <20200623193352.4mdmfg4mfmgfeku4@kafai-mbp.dhcp.thefacebook.com> User-agent: mu4e 1.1.0; emacs 26.3 From: Jakub Sitnicki To: Martin KaFai Lau Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com, Andrii Nakryiko Subject: Re: [PATCH bpf-next v2 2/3] bpf, netns: Keep attached programs in bpf_prog_array In-reply-to: <20200623193352.4mdmfg4mfmgfeku4@kafai-mbp.dhcp.thefacebook.com> Date: Tue, 23 Jun 2020 22:59:37 +0200 Message-ID: <87sgelmrba.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Jun 23, 2020 at 09:33 PM CEST, Martin KaFai Lau wrote: > On Tue, Jun 23, 2020 at 12:34:58PM +0200, Jakub Sitnicki wrote: > > [ ... ] > >> @@ -93,8 +108,16 @@ static int bpf_netns_link_update_prog(struct bpf_link *link, >> goto out_unlock; >> } >> >> + run_array = rcu_dereference_protected(net->bpf.run_array[type], >> + lockdep_is_held(&netns_bpf_mutex)); >> + if (run_array) >> + ret = bpf_prog_array_replace_item(run_array, link->prog, new_prog); >> + else > When will this happen? This will never happen, unless there is a bug. As long as there is a link attached, run_array should never be detached (null). Because it can be handled gracefully, we fail the bpf(LINK_UPDATE) syscall. Your question makes me think that perhaps it should trigger a warning, with WARN_ON_ONCE, to signal clearly to the reader that this is an unexpected state. WDYT? > >> + ret = -ENOENT; >> + if (ret) >> + goto out_unlock; >> + >> old_prog = xchg(&link->prog, new_prog); >> - rcu_assign_pointer(net->bpf.progs[type], new_prog); >> bpf_prog_put(old_prog); >> >> out_unlock: >> @@ -142,14 +165,38 @@ static const struct bpf_link_ops bpf_netns_link_ops = { >> .show_fdinfo = bpf_netns_link_show_fdinfo, >> };