From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5DD151A14E; Fri, 18 Sep 2026 17:24:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789752300; cv=none; b=ffbx0DWUStPkMvxPG/JeYIppocjWB4TMQCr7dEU+y2Qdmtw530QG/jdd9uX49yjmEglrgYsRTkNZMivM0lYYCG+93okbMM8TjF5g5VnTuk0Rdw/GbpgbkdP7QedJYth/MWfyc6jQnXuMwiELjWyOr+Deb4W4eqzhfK3Ph4lBUSY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789752300; c=relaxed/simple; bh=vUh7k6/sgzYvC1EwkqVYUJP2zwwUD/OVrEJJTTCiv6w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Sgdl27HDSZ7R3biAepuY9iOeNCBUTOfm8jyd2yVlMN/664nl+ZtOLHizUfiJJtiVsPHkr385rzQPwJCy/49Qyal0n5EFTQGSdTrTgK1m/awiVdz+iWCiMCRDZBG8WPj1nVhj+1ZoToyu22v5sXEoupnPMsT7ts1vmBt6SW/lSIk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=CCxLPu7K; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="CCxLPu7K" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=w5 fWPWYIbg6KghdEbDIe/kAKt5hevm4hGcALmYK1xKI=; b=CCxLPu7KgvBIuMgU1t 2ojYib9vk5rrQGqFSA2juOyQSQvQuTnO2SZ7d99IxSa2leH/E+QFXbV6AKBY4Fz+ U/WHg7amkEUx9ODaHlYwWhnpqU80hebvK4g5DgB95beeWSvng9G7o35VJyuGmTpv QJ0Q5Xjq7XY+zLZcBC98i9cQI= Received: from localhost (unknown []) by gzsmtp4 (Coremail) with SMTP id PygvCgAXUUq7c61qHvN9AA--.16484S2; Sat, 19 Sep 2026 01:24:12 +0800 (CST) From: Hui Su To: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi Cc: Yonghong Song , Quentin Monnet , Martin KaFai Lau , Song Liu , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hui Su Subject: [PATCH bpf 3/3] bpftool: Add support for BPF_F_PREORDER cgroup attach flag Date: Sat, 19 Sep 2026 02:24:07 +0900 Message-ID: <20260918172407.3459188-4-sh_def@163.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260918172407.3459188-1-sh_def@163.com> References: <20260918172407.3459188-1-sh_def@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:PygvCgAXUUq7c61qHvN9AA--.16484S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxKr17Cr1DGry7XF1kCw47twb_yoWxWr4rpF 4kXFyUK3WrW3sxXa1xC390gFWFgrs7WFWUCFy5Jw1Y9FW3Gw1vkrWfKFWF9rn8XFW3Aw40 vrWYvr45WF1jvFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0pi5CzJUUUUU= X-CM-SenderInfo: xvkbvvri6rljoofrz/xtbC6hwScWqtc7yeHAAA3f Commit 4b82b181a26c ("bpf: Allow pre-ordering for bpf cgroup progs") introduced BPF_F_PREORDER to request pre-order execution across the cgroup hierarchy. Furthermore, attachments legitimately use combinations such as BPF_F_ALLOW_MULTI | BPF_F_PREORDER. With BPF_PROG_QUERY reporting the per-program BPF_F_PREORDER attribute, bpftool's exact-match formatter falls back to "unknown(40)" when BPF_F_PREORDER is present alone, or "unknown(42)" when combined with BPF_F_ALLOW_MULTI. Additionally, do_attach() only accepts "multi" and "override", rejecting "preorder" with "unknown option". Before: $ bpftool cgroup show 1234 cgroup_inet_ingress unknown(42) test_prog $ bpftool cgroup attach cgroup_inet_ingress id 5678 multi preorder Error: unknown option: preorder After: $ bpftool cgroup show 1234 cgroup_inet_ingress multi,preorder test_prog $ bpftool cgroup attach cgroup_inet_ingress id 5678 multi preorder (attaches successfully) Refactor the attach flags formatter to use a bitmask formatter that outputs comma-separated flag names while preserving unrecognized bits as "unknown(...)". Also accept "preorder" in do_attach(), and update bpftool-cgroup.rst, usage help, and bash completion. Signed-off-by: Hui Su --- .../bpftool/Documentation/bpftool-cgroup.rst | 9 ++- tools/bpf/bpftool/bash-completion/bpftool | 2 +- tools/bpf/bpftool/cgroup.c | 55 +++++++++++++------ 3 files changed, 45 insertions(+), 21 deletions(-) diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst index e8185596a759..8ec2546c0b8e 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst @@ -45,7 +45,7 @@ CGROUP COMMANDS | **cgroup_unix_recvmsg** | **cgroup_sysctl** | | **cgroup_getsockopt** | **cgroup_setsockopt** | | **cgroup_inet_sock_release** } -| *ATTACH_FLAGS* := { **multi** | **override** } +| *ATTACH_FLAGS* := { **multi** | **override** | **preorder** } DESCRIPTION =========== @@ -75,10 +75,13 @@ bpftool cgroup attach *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*] Attach program *PROG* to the cgroup *CGROUP* with attach type *ATTACH_TYPE* and optional *ATTACH_FLAGS*. - *ATTACH_FLAGS* can be one of: **override** if a sub-cgroup installs some + *ATTACH_FLAGS* can include: **override** if a sub-cgroup installs some bpf program, the program in this cgroup yields to sub-cgroup program; **multi** if a sub-cgroup installs some bpf program, that cgroup program - gets run in addition to the program in this cgroup. + gets run in addition to the program in this cgroup; + **preorder** requests that this program executes before programs attached + further down the cgroup hierarchy during evaluation. **preorder** can be + combined with **multi**. Only one program is allowed to be attached to a cgroup with no attach flags or the **override** flag. Attaching another program will release old diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool index 75cbcb512eba..819757d7a360 100644 --- a/tools/bpf/bpftool/bash-completion/bpftool +++ b/tools/bpf/bpftool/bash-completion/bpftool @@ -1057,7 +1057,7 @@ _bpftool() attach|detach) local BPFTOOL_CGROUP_ATTACH_TYPES="$(bpftool feature list_builtins attach_types 2>/dev/null | \ grep '^cgroup_')" - local ATTACH_FLAGS='multi override' + local ATTACH_FLAGS='multi override preorder' # Check for $prev = $command first if [ $prev = $command ]; then _filedir diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index ce69d1e5468e..aec1281c95d8 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -56,7 +56,7 @@ static const int cgroup_attach_types[] = { }; #define HELP_SPEC_ATTACH_FLAGS \ - "ATTACH_FLAGS := { multi | override }" + "ATTACH_FLAGS := { multi | override | preorder }" #define HELP_SPEC_ATTACH_TYPES \ " ATTACH_TYPE := { cgroup_inet_ingress | cgroup_inet_egress |\n" \ @@ -269,6 +269,39 @@ static int show_effective_bpf_progs(int cgroup_fd, enum bpf_attach_type type, return 0; } +static const char *format_attach_flags(__u32 attach_flags, char *buf, size_t sz) +{ + static const struct { + __u32 flag; + const char *name; + } flags[] = { + { BPF_F_ALLOW_MULTI, "multi" }, + { BPF_F_ALLOW_OVERRIDE, "override" }, + { BPF_F_PREORDER, "preorder" }, + }; + size_t len = 0; + size_t i; + int n; + + buf[0] = '\0'; + for (i = 0; i < ARRAY_SIZE(flags); i++) { + if (attach_flags & flags[i].flag) { + n = snprintf(buf + len, sz - len, "%s%s", + len ? "," : "", flags[i].name); + if (n < 0 || (size_t)n >= sz - len) + return buf; + len += n; + attach_flags &= ~flags[i].flag; + } + } + + if (attach_flags) + snprintf(buf + len, sz - len, "%sunknown(%x)", + len ? "," : "", attach_flags); + + return buf; +} + static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, int level) { @@ -276,7 +309,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, __u32 prog_attach_flags[1024] = {0}; const char *attach_flags_str; __u32 prog_ids[1024] = {0}; - char buf[32]; + char buf[64]; __u32 iter; int ret; @@ -296,21 +329,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, __u32 attach_flags; attach_flags = prog_attach_flags[iter] ?: p.attach_flags; - - switch (attach_flags) { - case BPF_F_ALLOW_MULTI: - attach_flags_str = "multi"; - break; - case BPF_F_ALLOW_OVERRIDE: - attach_flags_str = "override"; - break; - case 0: - attach_flags_str = ""; - break; - default: - snprintf(buf, sizeof(buf), "unknown(%x)", attach_flags); - attach_flags_str = buf; - } + attach_flags_str = format_attach_flags(attach_flags, buf, sizeof(buf)); show_bpf_prog(prog_ids[iter], type, attach_flags_str, level); @@ -593,6 +612,8 @@ static int do_attach(int argc, char **argv) attach_flags |= BPF_F_ALLOW_MULTI; } else if (is_prefix(argv[i], "override")) { attach_flags |= BPF_F_ALLOW_OVERRIDE; + } else if (is_prefix(argv[i], "preorder")) { + attach_flags |= BPF_F_PREORDER; } else { p_err("unknown option: %s", argv[i]); goto exit_cgroup; -- 2.55.0