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 79607C678D5 for ; Wed, 8 Mar 2023 22:33:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229708AbjCHWdH (ORCPT ); Wed, 8 Mar 2023 17:33:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229572AbjCHWdF (ORCPT ); Wed, 8 Mar 2023 17:33:05 -0500 Received: from out-32.mta1.migadu.com (out-32.mta1.migadu.com [IPv6:2001:41d0:203:375::20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6320D196A8 for ; Wed, 8 Mar 2023 14:33:00 -0800 (PST) Message-ID: <1a6c3d38-b55c-bde8-3b99-e52a5ac028b9@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1678314778; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RB/Cc3Bm4bnm5R1V9f7gpJvvsl3w9tyqhJ4LKIWoRz4=; b=R07ylwJR69DAhWG+OM0vt5MhUod3tUXhR880mkQhenR5Pcj7bH0TdSC4+0diHHTF8Qdt5W MF9a1IRmf4xU/AKg3JJmkFRd0zppHE1YoG3gM3jJ+tVPvXjps9Igmm2SrqGTbIJ+8O4P1j ByXE8J/4ocE5uV95+0UphdBmsp0Z7BI= Date: Wed, 8 Mar 2023 14:32:55 -0800 MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v5 6/8] libbpf: Update a bpf_link with another struct_ops. Content-Language: en-US To: Kui-Feng Lee References: <20230308005050.255859-1-kuifeng@meta.com> <20230308005050.255859-7-kuifeng@meta.com> Cc: bpf@vger.kernel.org, ast@kernel.org, song@kernel.org, kernel-team@meta.com, andrii@kernel.org, sdf@google.com X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: <20230308005050.255859-7-kuifeng@meta.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 3/7/23 4:50 PM, Kui-Feng Lee wrote: > Introduce bpf_link__update_struct_ops(), which will allow you to > effortlessly transition the struct_ops map of any given bpf_link into > an alternative. > > Signed-off-by: Kui-Feng Lee > --- > tools/lib/bpf/libbpf.c | 36 ++++++++++++++++++++++++++++++++++++ > tools/lib/bpf/libbpf.h | 1 + > tools/lib/bpf/libbpf.map | 1 + > 3 files changed, 38 insertions(+) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index f70b55c0f40e..0406d0e00e1f 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -11657,6 +11657,42 @@ 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, fd; > + > + if (!bpf_map__is_struct_ops(map) || map->fd == -1) > + 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); > + if (err && errno != EBUSY) { > + err = -errno; > + free(link); hmm... this looks wrong to free here. > + return err; > + } > + > + fd = bpf_link_update(link->fd, map->fd, NULL); > + if (fd < 0) { > + err = -errno; > + free(link); same here. > + 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..cc05be376257 100644 > --- a/tools/lib/bpf/libbpf.map > +++ b/tools/lib/bpf/libbpf.map > @@ -387,6 +387,7 @@ LIBBPF_1.2.0 { > global: > bpf_btf_get_info_by_fd; > bpf_link_get_info_by_fd; > + bpf_link__update_map; > bpf_map_get_info_by_fd; > bpf_prog_get_info_by_fd; > } LIBBPF_1.1.0;