From patchwork Tue Apr 11 04:16:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13207024 X-Patchwork-Delegate: bpf@iogearbox.net 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 127E0C77B70 for ; Tue, 11 Apr 2023 04:16:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230034AbjDKEQm (ORCPT ); Tue, 11 Apr 2023 00:16:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229889AbjDKEQl (ORCPT ); Tue, 11 Apr 2023 00:16:41 -0400 Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE10EE74; Mon, 10 Apr 2023 21:16:40 -0700 (PDT) Received: by mail-qt1-f169.google.com with SMTP id ge18so3761643qtb.0; Mon, 10 Apr 2023 21:16:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681186600; x=1683778600; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=f8r9n+ovWuQwy53nYZcyLOjkE/UdHOnvkJQHdAE1iAk=; b=JZY+S84zh2AgwldcJGTKW7KuYjVH6MS8xoNv9hBAfPnYRWbDjVJYpGx3AChTmRVwg2 GuuGta+B9rAb5hjXpdLYMb3a/VeRGB1wL0fhFENnqI50cE65QJidDOmoE/1FPA7XI7Np sOVMvwCw1MMM7e/HZvpYaKhCFPhauOsGvuw5VS4IcwI377b2RktPA9w7NNna9UbipUGD hk7Lzuubg+5dIyAg7O4pkkJsV30W1IR2ks9PzlysFJiOAIm4nKy7mVyccPWXXVTaHST7 NjF5hPqKm5YTnpal7JLO5C8pHHmYbMiLHQffnBznNG9+FtJlaFh8vB7Fr0zjeg7/ewP3 ve5g== X-Gm-Message-State: AAQBX9doZCAP12EHOqtA1DI8U1eLT+55Th/iBWikPbJeW9qWhbcdvnZw DWH5lZ+KiqtKTHQyxMOfTBDz1lYsVhzFtacf X-Google-Smtp-Source: AKy350btqlac7ZrP9R2ICxEcCNBoBLYonnNWTvqR/JvPs0K5+sO1mKnH6AegPBQJDMcAPZ4FPrTNvw== X-Received: by 2002:a05:622a:130f:b0:3e6:720f:bad7 with SMTP id v15-20020a05622a130f00b003e6720fbad7mr19864719qtk.54.1681186599543; Mon, 10 Apr 2023 21:16:39 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:8681]) by smtp.gmail.com with ESMTPSA id o76-20020a37414f000000b007486052d731sm3738297qka.10.2023.04.10.21.16.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Apr 2023 21:16:39 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: [PATCH bpf-next 3/3] bpf,docs: Remove references to bpf_cgroup_kptr_get() Date: Mon, 10 Apr 2023 23:16:33 -0500 Message-Id: <20230411041633.179404-3-void@manifault.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230411041633.179404-1-void@manifault.com> References: <20230411041633.179404-1-void@manifault.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The bpf_cgroup_kptr_get() kfunc has been removed, and bpf_cgroup_acquire() / bpf_cgroup_release() now have the same semantics as bpf_task_acquire() / bpf_task_release(). This patch updates the BPF documentation to reflect this. Signed-off-by: David Vernet --- Documentation/bpf/kfuncs.rst | 68 ------------------------------------ 1 file changed, 68 deletions(-) diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index d8a16c4bef7f..3b42cfe12437 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -572,74 +572,6 @@ bpf_task_release() respectively, so we won't provide examples for them. ---- -You may also acquire a reference to a ``struct cgroup`` kptr that's already -stored in a map using bpf_cgroup_kptr_get(): - -.. kernel-doc:: kernel/bpf/helpers.c - :identifiers: bpf_cgroup_kptr_get - -Here's an example of how it can be used: - -.. code-block:: c - - /* struct containing the struct task_struct kptr which is actually stored in the map. */ - struct __cgroups_kfunc_map_value { - struct cgroup __kptr * cgroup; - }; - - /* The map containing struct __cgroups_kfunc_map_value entries. */ - struct { - __uint(type, BPF_MAP_TYPE_HASH); - __type(key, int); - __type(value, struct __cgroups_kfunc_map_value); - __uint(max_entries, 1); - } __cgroups_kfunc_map SEC(".maps"); - - /* ... */ - - /** - * A simple example tracepoint program showing how a - * struct cgroup kptr that is stored in a map can - * be acquired using the bpf_cgroup_kptr_get() kfunc. - */ - SEC("tp_btf/cgroup_mkdir") - int BPF_PROG(cgroup_kptr_get_example, struct cgroup *cgrp, const char *path) - { - struct cgroup *kptr; - struct __cgroups_kfunc_map_value *v; - s32 id = cgrp->self.id; - - /* Assume a cgroup kptr was previously stored in the map. */ - v = bpf_map_lookup_elem(&__cgroups_kfunc_map, &id); - if (!v) - return -ENOENT; - - /* Acquire a reference to the cgroup kptr that's already stored in the map. */ - kptr = bpf_cgroup_kptr_get(&v->cgroup); - if (!kptr) - /* If no cgroup was present in the map, it's because - * we're racing with another CPU that removed it with - * bpf_kptr_xchg() between the bpf_map_lookup_elem() - * above, and our call to bpf_cgroup_kptr_get(). - * bpf_cgroup_kptr_get() internally safely handles this - * race, and will return NULL if the task is no longer - * present in the map by the time we invoke the kfunc. - */ - return -EBUSY; - - /* Free the reference we just took above. Note that the - * original struct cgroup kptr is still in the map. It will - * be freed either at a later time if another context deletes - * it from the map, or automatically by the BPF subsystem if - * it's still present when the map is destroyed. - */ - bpf_cgroup_release(kptr); - - return 0; - } - ----- - Other kfuncs available for interacting with ``struct cgroup *`` objects are bpf_cgroup_ancestor() and bpf_cgroup_from_id(), allowing callers to access the ancestor of a cgroup and find a cgroup by its ID, respectively. Both