From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) (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 344ED3403E8; Tue, 22 Sep 2026 02:55:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790045730; cv=none; b=IuIVxt8LmXhmbwJQraLOYTWD/BD1etKQibSSjf9HSMGbQEWivPQ0ZlaNps8BMTl97LPnFB/4L6bARJ6D+mH6qvvxiAjbYcs02OendXc4D4NmFZr4mK4BlGlgrYETxx96P1NLbz8FMmSo9vVkswpfYcYwK+UUb0kus771wA4X4yg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790045730; c=relaxed/simple; bh=hK7dnz1fNm88X0+jYTY2ejo9vM/95ELnAQpFUBTeMt8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=a0zN5ZVnHtBQl9QBwrlatoBd9nprwCutJhgL6tf2dAogPUWCT/z29tGvvGxCSG90Ypq8v9u3NTJex6gs7eh6mUtZ/vZZxMeLkMimAXcaAKJexbcMCx6xtS5M5Pvhao/PXefMPhbWth/1goNrS1pWT8XLogSidf8GScEXJ4awPEM= 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=J4Aphnuh; arc=none smtp.client-ip=220.197.31.3 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="J4Aphnuh" 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=ec P5t7ttauiOdWWIApxVQOiSA4P1UHFyxmZ+YpcJYfc=; b=J4AphnuhfyBUSRdBLC ynguUWmRdK1MFqgGH5eEYYcKAFpDhh1c5gWGhSOL36uXJFHpHJjxrd+kCGsGkabf m4s65EGHSoIfOozGJoJia+6GPYEh3rlCFUt6aeaDY9GFtQElEoLj2qSL8uGk2RFR /B7SgK/EGj1MZtu1190g6k7Lg= Received: from localhost (unknown []) by gzsmtp5 (Coremail) with SMTP id QCgvCgB3DGn27bFqwKviAg--.7291S2; Tue, 22 Sep 2026 10:54:47 +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-next v3 3/3] bpftool: Add support for BPF_F_PREORDER cgroup attach flag Date: Tue, 22 Sep 2026 11:54:42 +0900 Message-ID: <20260922025442.3176057-4-sh_def@163.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260922025442.3176057-1-sh_def@163.com> References: <20260922025442.3176057-1-sh_def@163.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:QCgvCgB3DGn27bFqwKviAg--.7291S2 X-Coremail-Antispam: 1Uf129KBjvJXoW3Cw4kJr4DCw4DAryfKr13CFg_yoWkGw1DpF 4kXa4jk3W8W3sxWw48G3yYgrWrKrs7WF1UCF98Jry5uFW3Ww1vyrWSkFWrurn8XFWxAw40 vF4Yvr15WF1jvFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0pi5CzJUUUUU= X-CM-SenderInfo: xvkbvvri6rljoofrz/xtbCwhe-H2qx7feniAAA3b 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 or BPF_F_ALLOW_OVERRIDE | 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(41)" / "unknown(42)" when combined with BPF_F_ALLOW_OVERRIDE or 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 into a bitmask formatter that outputs comma-separated flag names for plain text while preserving unrecognized bits as "unknown(...)". Render attach flags as an array of flag names in JSON output. Accept "preorder" in do_attach(), update the cgroup documentation and synopsis to express valid flag combinations, and teach bash completion about them ("multi" or "override" optionally combined with "preorder"). Signed-off-by: Hui Su --- Notes (bpf-preorder-v3-20260922-check): Testing: - PASS: make -C tools/bpf/bpftool -j12 (fresh after rebase). - PASS: make -C tools/bpf/bpftool/Documentation -j12 (fresh after rebase). - PASS: bash -n tools/bpf/bpftool/bash-completion/bpftool (fresh after rebase). - PASS: bpftool cgroup plain-text and JSON runtime smoke (x86_64 QEMU/KVM); result reused after a content-equivalent rebase. - PASS: scripts/checkpatch.pl on the generated v3 patches. .../bpftool/Documentation/bpftool-cgroup.rst | 25 +++-- tools/bpf/bpftool/bash-completion/bpftool | 4 +- tools/bpf/bpftool/cgroup.c | 99 +++++++++++++------ 3 files changed, 89 insertions(+), 39 deletions(-) diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst index e8185596a759..d1b8193dc576 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 =========== @@ -75,20 +75,27 @@ 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 ancestor-to-descendant execution for this program, + before non-preorder programs, which execute descendants-to-ancestors + across the cgroup hierarchy. Note that **preorder** alone does not enable + multi-program attachment; specify **multi** together with **preorder** to + attach multiple programs. - 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 - program and attach the new one. + Only one program is allowed to be attached to a cgroup unless the + **multi** flag is specified. Without **multi**, attaching another program + replaces the existing program, provided the **override** setting matches. Multiple programs are allowed to be attached to a cgroup with **multi**. - They are executed in FIFO order (those that were attached first, run - first). + Programs marked with **preorder** are placed before non-preorder programs + in the effective program array. Within each ordering class at the same + cgroup level, attachment order is preserved. - Non-default *ATTACH_FLAGS* are supported by kernel version 4.14 and later. + **multi** and **override** are supported by kernel version 4.14 and later. + **preorder** was introduced upstream in Linux 6.15. *ATTACH_TYPE* can be one of: diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool index c9e8761e4ef2..9d9ced270685 100644 --- a/tools/bpf/bpftool/bash-completion/bpftool +++ b/tools/bpf/bpftool/bash-completion/bpftool @@ -1064,7 +1064,6 @@ _bpftool() attach|detach) local BPFTOOL_CGROUP_ATTACH_TYPES="$(bpftool feature list_builtins attach_types 2>/dev/null | \ grep '^cgroup_')" - local ATTACH_FLAGS='multi override' # Check for $prev = $command first if [ $prev = $command ]; then _filedir @@ -1094,7 +1093,8 @@ _bpftool() # "id|pinned|tag|name" (we already checked for # that). This should only leave the case when # we need attach flags for "attach" commamnd. - _bpftool_one_of_list "$ATTACH_FLAGS" + _bpftool_one_of_list 'multi override' + _bpftool_once_attr 'preorder' fi return 0 ;; diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index ce69d1e5468e..fee1a260f6d1 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" \ @@ -138,11 +138,69 @@ static void guess_vmlinux_btf_id(__u32 attach_btf_obj_id) close(fd); } +static const struct { + __u32 flag; + const char *name; +} attach_flag_names[] = { + { BPF_F_ALLOW_MULTI, "multi" }, + { BPF_F_ALLOW_OVERRIDE, "override" }, + { BPF_F_PREORDER, "preorder" }, +}; + +static const char *format_attach_flags(__u32 flags, char *buf, size_t sz) +{ + size_t len = 0; + size_t i; + int n; + + buf[0] = '\0'; + for (i = 0; i < ARRAY_SIZE(attach_flag_names); i++) { + if (flags & attach_flag_names[i].flag) { + n = snprintf(buf + len, sz - len, "%s%s", + len ? "," : "", attach_flag_names[i].name); + if (n < 0 || (size_t)n >= sz - len) + return buf; + len += n; + flags &= ~attach_flag_names[i].flag; + } + } + + if (flags) + snprintf(buf + len, sz - len, "%sunknown(%x)", + len ? "," : "", flags); + + return buf; +} + +static void show_attach_flags_json(__u32 flags) +{ + char buf[32]; + size_t i; + + jsonw_name(json_wtr, "attach_flags"); + jsonw_start_array(json_wtr); + + for (i = 0; i < ARRAY_SIZE(attach_flag_names); i++) { + if (!(flags & attach_flag_names[i].flag)) + continue; + + jsonw_string(json_wtr, attach_flag_names[i].name); + flags &= ~attach_flag_names[i].flag; + } + + if (flags) { + snprintf(buf, sizeof(buf), "unknown(%x)", flags); + jsonw_string(json_wtr, buf); + } + + jsonw_end_array(json_wtr); +} + static int show_bpf_prog(int id, enum bpf_attach_type attach_type, - const char *attach_flags_str, - int level) + __u32 attach_flags, int level) { char prog_name[MAX_PROG_FULL_NAME]; + char attach_flags_str[64]; const char *attach_btf_name = NULL; struct bpf_prog_info info = {}; const char *attach_type_str; @@ -182,7 +240,7 @@ static int show_bpf_prog(int id, enum bpf_attach_type attach_type, else jsonw_uint_field(json_wtr, "attach_type", attach_type); if (!(query_flags & BPF_F_QUERY_EFFECTIVE)) - jsonw_string_field(json_wtr, "attach_flags", attach_flags_str); + show_attach_flags_json(attach_flags); jsonw_string_field(json_wtr, "name", prog_name); if (attach_btf_name) jsonw_string_field(json_wtr, "attach_btf_name", attach_btf_name); @@ -198,7 +256,9 @@ static int show_bpf_prog(int id, enum bpf_attach_type attach_type, if (query_flags & BPF_F_QUERY_EFFECTIVE) printf(" %-15s", prog_name); else - printf(" %-15s %-15s", attach_flags_str, prog_name); + printf(" %-17s %-15s", + format_attach_flags(attach_flags, attach_flags_str, + sizeof(attach_flags_str)), prog_name); if (attach_btf_name) printf(" %-15s", attach_btf_name); else if (info.attach_btf_id) @@ -264,7 +324,7 @@ static int show_effective_bpf_progs(int cgroup_fd, enum bpf_attach_type type, return 0; for (iter = 0; iter < p.prog_cnt; iter++) - show_bpf_prog(prog_ids[iter], type, NULL, level); + show_bpf_prog(prog_ids[iter], type, 0, level); return 0; } @@ -274,9 +334,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, { LIBBPF_OPTS(bpf_prog_query_opts, p); __u32 prog_attach_flags[1024] = {0}; - const char *attach_flags_str; __u32 prog_ids[1024] = {0}; - char buf[32]; __u32 iter; int ret; @@ -296,24 +354,7 @@ 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; - } - - show_bpf_prog(prog_ids[iter], type, - attach_flags_str, level); + show_bpf_prog(prog_ids[iter], type, attach_flags, level); } return 0; @@ -377,7 +418,7 @@ static int do_show(int argc, char **argv) else if (query_flags & BPF_F_QUERY_EFFECTIVE) printf("%-8s %-15s %-15s\n", "ID", "AttachType", "Name"); else - printf("%-8s %-15s %-15s %-15s\n", "ID", "AttachType", + printf("%-8s %-15s %-17s %-15s\n", "ID", "AttachType", "AttachFlags", "Name"); btf_vmlinux = libbpf_find_kernel_btf(); @@ -531,7 +572,7 @@ static int do_show_tree(int argc, char **argv) "ID", "AttachType", "Name"); else printf("%s\n" - "%-8s %-15s %-15s %-15s\n", + "%-8s %-15s %-17s %-15s\n", "CgroupPath", "ID", "AttachType", "AttachFlags", "Name"); @@ -593,6 +634,8 @@ 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