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b623181520
test_bpftool_synctypes.py helps detecting inconsistencies in bpftool
between the different list of types and options scattered in the
sources, the documentation, and the bash completion. For options that
apply to all bpftool commands, the script had a hardcoded list of
values, and would use them to check whether the man pages are
up-to-date. When writing the script, it felt acceptable to have this
list in order to avoid to open and parse bpftool's main.h every time,
and because the list of global options in bpftool doesn't change so
often.
However, this is prone to omissions, and we recently added a new
-l|--legacy option which was described in common_options.rst, but not
listed in the options summary of each manual page. The script did not
complain, because it keeps comparing the hardcoded list to the (now)
outdated list in the header file.
To address the issue, this commit brings the following changes:
- Options that are common to all bpftool commands (--json, --pretty, and
--debug) are moved to a dedicated file, and used in the definition of
a RST substitution. This substitution is used in the sources of all
the man pages.
- This list of common options is updated, with the addition of the new
-l|--legacy option.
- The script test_bpftool_synctypes.py is updated to compare:
- Options specific to a command, found in C files, for the
interactive help messages, with the same specific options from the
relevant man page for that command.
- Common options, checked just once: the list in main.h is
compared with the new list in substitutions.rst.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211115225844.33943-3-quentin@isovalent.com
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.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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================
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bpftool-link
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================
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-------------------------------------------------------------------------------
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tool for inspection and simple manipulation of eBPF links
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-------------------------------------------------------------------------------
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:Manual section: 8
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.. include:: substitutions.rst
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SYNOPSIS
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========
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**bpftool** [*OPTIONS*] **link** *COMMAND*
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*OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } }
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*COMMANDS* := { **show** | **list** | **pin** | **help** }
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LINK COMMANDS
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=============
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| **bpftool** **link { show | list }** [*LINK*]
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| **bpftool** **link pin** *LINK* *FILE*
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| **bpftool** **link detach** *LINK*
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| **bpftool** **link help**
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| *LINK* := { **id** *LINK_ID* | **pinned** *FILE* }
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DESCRIPTION
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===========
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**bpftool link { show | list }** [*LINK*]
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Show information about active links. If *LINK* is
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specified show information only about given link,
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otherwise list all links currently active on the system.
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Output will start with link ID followed by link type and
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zero or more named attributes, some of which depend on type
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of link.
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Since Linux 5.8 bpftool is able to discover information about
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processes that hold open file descriptors (FDs) against BPF
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links. On such kernels bpftool will automatically emit this
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information as well.
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**bpftool link pin** *LINK* *FILE*
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Pin link *LINK* as *FILE*.
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Note: *FILE* must be located in *bpffs* mount. It must not
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contain a dot character ('.'), which is reserved for future
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extensions of *bpffs*.
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**bpftool link detach** *LINK*
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Force-detach link *LINK*. BPF link and its underlying BPF
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program will stay valid, but they will be detached from the
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respective BPF hook and BPF link will transition into
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a defunct state until last open file descriptor for that
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link is closed.
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**bpftool link help**
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Print short help message.
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OPTIONS
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=======
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.. include:: common_options.rst
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-f, --bpffs
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When showing BPF links, show file names of pinned
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links.
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-n, --nomount
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Do not automatically attempt to mount any virtual file system
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(such as tracefs or BPF virtual file system) when necessary.
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EXAMPLES
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========
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**# bpftool link show**
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::
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10: cgroup prog 25
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cgroup_id 614 attach_type egress
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pids test_progs(223)
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**# bpftool --json --pretty link show**
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::
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[{
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"type": "cgroup",
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"prog_id": 25,
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"cgroup_id": 614,
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"attach_type": "egress",
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"pids": [{
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"pid": 223,
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"comm": "test_progs"
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}
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]
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}
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]
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| **# bpftool link pin id 10 /sys/fs/bpf/link**
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| **# ls -l /sys/fs/bpf/**
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::
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-rw------- 1 root root 0 Apr 23 21:39 link
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