From patchwork Tue Mar 21 23:28:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kui-Feng Lee X-Patchwork-Id: 13183380 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 8B781C76195 for ; Tue, 21 Mar 2023 23:28:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229626AbjCUX2f (ORCPT ); Tue, 21 Mar 2023 19:28:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229726AbjCUX2e (ORCPT ); Tue, 21 Mar 2023 19:28:34 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF8B3AD3D for ; Tue, 21 Mar 2023 16:28:33 -0700 (PDT) Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 32LNGM4v023353 for ; Tue, 21 Mar 2023 16:28:33 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=s2048-2021-q4; bh=6wXgogHTMYW+4Nt4YJrx7N257U8fBF1xjVX2322Po08=; b=bcAVK2HvAzQCX4CQyMNd5vaDpBcymYJkV0Av9Sk5QbXrCVI9Zf4MgCjPSnzIQ1I5dsrI VVn+kHGS2i+2qdtRrW+xg2bF0fGkhVgE8A/JW87713lAgFVKEKy4e1aJOLrrNAaaq6hN w4MISBf2t97mfpeHQ8MJ4xot/Lg9X8WG70r/urn4PVf40L1zItr7HnyEMbF4bYOH6J1O yb2aQuUEb4AA2+kXDGAwGpIhw7Mawyoceb5q2/m+fXBeADimMSF49n3C/CRJb48ib9cQ P12u28251ZD0W0GmNj4C5Y+xIvyPul/yAJjAR8T1SdXOxTzxrQa8T6HAtZn8gVxSOx8k aQ== Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3pf07cyqcf-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 21 Mar 2023 16:28:32 -0700 Received: from twshared34471.14.frc2.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Tue, 21 Mar 2023 16:28:30 -0700 Received: by devbig931.frc1.facebook.com (Postfix, from userid 460691) id 862657EEB564; Tue, 21 Mar 2023 16:28:15 -0700 (PDT) From: Kui-Feng Lee To: , , , , , , CC: Kui-Feng Lee Subject: [PATCH bpf-next v10 6/8] libbpf: Update a bpf_link with another struct_ops. Date: Tue, 21 Mar 2023 16:28:11 -0700 Message-ID: <20230321232813.3376064-7-kuifeng@meta.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230321232813.3376064-1-kuifeng@meta.com> References: <20230321232813.3376064-1-kuifeng@meta.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: rVnfs6iL1HdTbf9m-NDZ72AqMf3O436U X-Proofpoint-GUID: rVnfs6iL1HdTbf9m-NDZ72AqMf3O436U X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-21_11,2023-03-21_01,2023-02-09_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Introduce bpf_link__update_map(), which allows to atomically update underlying struct_ops implementation for given struct_ops BPF link Signed-off-by: Kui-Feng Lee --- tools/lib/bpf/bpf.h | 5 ++++- tools/lib/bpf/libbpf.c | 35 +++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 1 + tools/lib/bpf/libbpf.map | 1 + 4 files changed, 41 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index f0f786373238..4fae4e698a8e 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -335,7 +335,10 @@ LIBBPF_API int bpf_link_detach(int link_fd); struct bpf_link_update_opts { size_t sz; /* size of this struct for forward/backward compatibility */ __u32 flags; /* extra flags */ - __u32 old_prog_fd; /* expected old program FD */ + union { + __u32 old_prog_fd; /* expected old program FD */ + __u32 old_map_fd; /* expected old map FD */ + }; }; #define bpf_link_update_opts__last_field old_prog_fd diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 3b257d5170cb..935a7da501d7 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -11670,6 +11670,41 @@ struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) return &link->link; } +/* + * Swap the back struct_ops of a link with a new struct_ops map. + */ +int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map) +{ + struct bpf_link_struct_ops *st_ops_link; + __u32 zero = 0; + int err; + + if (!bpf_map__is_struct_ops(map) || map->fd < 0) + return -EINVAL; + + st_ops_link = container_of(link, struct bpf_link_struct_ops, link); + /* Ensure the type of a link is correct */ + if (st_ops_link->map_fd < 0) + return -EINVAL; + + err = bpf_map_update_elem(map->fd, &zero, map->st_ops->kern_vdata, 0); + /* It can be EBUSY if the map has been used to create or + * update a link before. We don't allow updating the value of + * a struct_ops once it is set. That ensures that the value + * never changed. So, it is safe to skip EBUSY. + */ + if (err && err != -EBUSY) + return err; + + err = bpf_link_update(link->fd, map->fd, NULL); + if (err < 0) + return err; + + st_ops_link->map_fd = map->fd; + + return 0; +} + typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr, void *private_data); diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index db4992a036f8..1615e55e2e79 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -719,6 +719,7 @@ bpf_program__attach_freplace(const struct bpf_program *prog, struct bpf_map; LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map); +LIBBPF_API int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map); struct bpf_iter_attach_opts { size_t sz; /* size of this struct for forward/backward compatibility */ diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 50dde1f6521e..a5aa3a383d69 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -386,6 +386,7 @@ LIBBPF_1.1.0 { LIBBPF_1.2.0 { global: bpf_btf_get_info_by_fd; + bpf_link__update_map; bpf_link_get_info_by_fd; bpf_map_get_info_by_fd; bpf_prog_get_info_by_fd;