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Diffstat (limited to 'tools/bpf/bpftool/Documentation/bpftool-link.rst')
| -rw-r--r-- | tools/bpf/bpftool/Documentation/bpftool-link.rst | 108 |
1 files changed, 47 insertions, 61 deletions
diff --git a/tools/bpf/bpftool/Documentation/bpftool-link.rst b/tools/bpf/bpftool/Documentation/bpftool-link.rst index 0e43d7b06c11..6f09d4405ed8 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-link.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-link.rst @@ -1,3 +1,5 @@ +.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) + ================ bpftool-link ================ @@ -7,72 +9,67 @@ tool for inspection and simple manipulation of eBPF links :Manual section: 8 +.. include:: substitutions.rst + SYNOPSIS ======== - **bpftool** [*OPTIONS*] **link** *COMMAND* +**bpftool** [*OPTIONS*] **link** *COMMAND* - *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } } +*OPTIONS* := { |COMMON_OPTIONS| | { **-f** | **--bpffs** } | { **-n** | **--nomount** } } - *COMMANDS* := { **show** | **list** | **pin** | **help** } +*COMMANDS* := { **show** | **list** | **pin** | **help** } LINK COMMANDS ============= -| **bpftool** **link { show | list }** [*LINK*] -| **bpftool** **link pin** *LINK* *FILE* -| **bpftool** **link help** +| **bpftool** **link { show | list }** [*LINK*] +| **bpftool** **link pin** *LINK* *FILE* +| **bpftool** **link detach** *LINK* +| **bpftool** **link help** | -| *LINK* := { **id** *LINK_ID* | **pinned** *FILE* } +| *LINK* := { **id** *LINK_ID* | **pinned** *FILE* } DESCRIPTION =========== - **bpftool link { show | list }** [*LINK*] - Show information about active links. If *LINK* is - specified show information only about given link, - otherwise list all links currently active on the system. - - Output will start with link ID followed by link type and - zero or more named attributes, some of which depend on type - of link. +bpftool link { show | list } [*LINK*] + Show information about active links. If *LINK* is specified show + information only about given link, otherwise list all links currently + active on the system. - **bpftool link pin** *LINK* *FILE* - Pin link *LINK* as *FILE*. + Output will start with link ID followed by link type and zero or more named + attributes, some of which depend on type of link. - Note: *FILE* must be located in *bpffs* mount. It must not - contain a dot character ('.'), which is reserved for future - extensions of *bpffs*. + Since Linux 5.8 bpftool is able to discover information about processes + that hold open file descriptors (FDs) against BPF links. On such kernels + bpftool will automatically emit this information as well. - **bpftool link help** - Print short help message. - -OPTIONS -======= - -h, --help - Print short generic help message (similar to **bpftool help**). +bpftool link pin *LINK* *FILE* + Pin link *LINK* as *FILE*. - -V, --version - Print version number (similar to **bpftool version**). + Note: *FILE* must be located in *bpffs* mount. It must not contain a dot + character ('.'), which is reserved for future extensions of *bpffs*. - -j, --json - Generate JSON output. For commands that cannot produce JSON, this - option has no effect. +bpftool link detach *LINK* + Force-detach link *LINK*. BPF link and its underlying BPF program will stay + valid, but they will be detached from the respective BPF hook and BPF link + will transition into a defunct state until last open file descriptor for + that link is closed. - -p, --pretty - Generate human-readable JSON output. Implies **-j**. +bpftool link help + Print short help message. - -f, --bpffs - When showing BPF links, show file names of pinned - links. +OPTIONS +======= + .. include:: common_options.rst - -n, --nomount - Do not automatically attempt to mount any virtual file system - (such as tracefs or BPF virtual file system) when necessary. + -f, --bpffs + When showing BPF links, show file names of pinned links. - -d, --debug - Print all logs available, even debug-level information. This - includes logs from libbpf. + -n, --nomount + Do not automatically attempt to mount any virtual file system (such as + tracefs or BPF virtual file system) when necessary. EXAMPLES ======== @@ -82,6 +79,7 @@ EXAMPLES 10: cgroup prog 25 cgroup_id 614 attach_type egress + pids test_progs(223) **# bpftool --json --pretty link show** @@ -91,7 +89,12 @@ EXAMPLES "type": "cgroup", "prog_id": 25, "cgroup_id": 614, - "attach_type": "egress" + "attach_type": "egress", + "pids": [{ + "pid": 223, + "comm": "test_progs" + } + ] } ] @@ -102,20 +105,3 @@ EXAMPLES :: -rw------- 1 root root 0 Apr 23 21:39 link - - -SEE ALSO -======== - **bpf**\ (2), - **bpf-helpers**\ (7), - **bpftool**\ (8), - **bpftool-btf**\ (8), - **bpftool-cgroup**\ (8), - **bpftool-feature**\ (8), - **bpftool-gen**\ (8), - **bpftool-iter**\ (8), - **bpftool-map**\ (8), - **bpftool-net**\ (8), - **bpftool-perf**\ (8), - **bpftool-prog**\ (8), - **bpftool-struct_ops**\ (8) |