On 4/19/23 16:40, Quentin Monnet wrote:
On Wed, 19 Apr 2023 at 03:56, Kui-Feng Lee <thinker.li@xxxxxxxxx> wrote:You can include an optional path after specifying the object name for the 'struct_ops register' subcommand. Since the commit 226bc6ae6405 ("Merge branch 'Transit between BPF TCP congestion controls.'") has been accepted, it is now possible to create a link for a struct_ops. This can be done by defining a struct_ops in SEC(".struct_ops.link") to make libbpf returns a real link. If we don't pin the links before leaving bpftool, they will disappear. To instruct bpftool to pin the links in a directory with the names of the maps, we need to provide the path of that directory. Signed-off-by: Kui-Feng Lee <kuifeng@xxxxxxxx>Right I'd forgotten we could register several struct_ops at once with the command. OK then, makes sense to pass a directory and pin with the existing names in that case. This patch looks all good, apart from a few indent nitpicks.--- tools/bpf/bpftool/common.c | 14 +++++++ tools/bpf/bpftool/main.h | 3 ++ tools/bpf/bpftool/prog.c | 13 ------ tools/bpf/bpftool/struct_ops.c | 76 ++++++++++++++++++++++++++++------ 4 files changed, 80 insertions(+), 26 deletions(-) diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c index 5a73ccf14332..1360c82ae732 100644 --- a/tools/bpf/bpftool/common.c +++ b/tools/bpf/bpftool/common.c @@ -1091,3 +1091,17 @@ const char *bpf_attach_type_input_str(enum bpf_attach_type t) default: return libbpf_bpf_attach_type_str(t); } } + +int pathname_concat(char *buf, int buf_sz, const char *path, + const char *name) +{ + int len; + + len = snprintf(buf, buf_sz, "%s/%s", path, name); + if (len < 0) + return -EINVAL; + if (len >= buf_sz) + return -ENAMETOOLONG; + + return 0; +} diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h index 0ef373cef4c7..f09853f24422 100644 --- a/tools/bpf/bpftool/main.h +++ b/tools/bpf/bpftool/main.h @@ -262,4 +262,7 @@ static inline bool hashmap__empty(struct hashmap *map) return map ? hashmap__size(map) == 0 : true; } +int pathname_concat(char *buf, int buf_sz, const char *path, + const char *name); + #endif diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index afbe3ec342c8..6024b7316875 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -1472,19 +1472,6 @@ auto_attach_program(struct bpf_program *prog, const char *path) return err; } -static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name) -{ - int len; - - len = snprintf(buf, buf_sz, "%s/%s", path, name); - if (len < 0) - return -EINVAL; - if ((size_t)len >= buf_sz) - return -ENAMETOOLONG; - - return 0; -} - static int auto_attach_programs(struct bpf_object *obj, const char *path) { diff --git a/tools/bpf/bpftool/struct_ops.c b/tools/bpf/bpftool/struct_ops.c index b389f4830e11..41643756e400 100644 --- a/tools/bpf/bpftool/struct_ops.c +++ b/tools/bpf/bpftool/struct_ops.c @@ -475,21 +475,48 @@ static int do_unregister(int argc, char **argv) return cmd_retval(&res, true); } +static int pin_link(struct bpf_link *link, const char *pindir, + const char *name) +{ + char pinfile[PATH_MAX]; + int err; + + err = pathname_concat(pinfile, sizeof(pinfile), pindir, name); + if (err) + return -1; + + err = bpf_link__pin(link, pinfile); + if (err) + return -1;"return bpf_link__pin(link, pinfile);" would work as well. But I don't mind much.
I will change to this.
+ + return 0; +} + static int do_register(int argc, char **argv) { LIBBPF_OPTS(bpf_object_open_opts, open_opts); + __u32 link_info_len = sizeof(struct bpf_link_info); + struct bpf_link_info link_info = {}; struct bpf_map_info info = {}; __u32 info_len = sizeof(info); int nr_errs = 0, nr_maps = 0; + const char *linkdir = NULL; struct bpf_object *obj; struct bpf_link *link; struct bpf_map *map; const char *file; - if (argc != 1) + if (argc != 1 && argc != 2) usage(); file = GET_ARG(); + if (argc == 1) + linkdir = GET_ARG(); + + if (linkdir && mount_bpffs_for_pin(linkdir)) { + p_err("can't mount bpffs for pinning"); + return -1; + } if (verifier_logs) /* log_level1 + log_level2 + stats, but not stable UAPI */ @@ -519,21 +546,44 @@ static int do_register(int argc, char **argv) } nr_maps++; - bpf_link__disconnect(link); - bpf_link__destroy(link); - - if (!bpf_map_get_info_by_fd(bpf_map__fd(map), &info, - &info_len)) - p_info("Registered %s %s id %u", - get_kern_struct_ops_name(&info), - bpf_map__name(map), - info.id); - else + if (bpf_map_get_info_by_fd(bpf_map__fd(map), &info, + &info_len)) { /* Not p_err. The struct_ops was attached * successfully. */ p_info("Registered %s but can't find id: %s", - bpf_map__name(map), strerror(errno)); + bpf_map__name(map), strerror(errno));I think the indent was correct and this change results from your previous version with "p_err()"?
Yes, it is my bad!
+ goto clean_link; + } + if (!(bpf_map__map_flags(map) & BPF_F_LINK)) { + p_info("Registered %s %s id %u", + get_kern_struct_ops_name(&info), + info.name, + info.id); + goto clean_link; + } + if (bpf_link_get_info_by_fd(bpf_link__fd(link), + &link_info,Please fix the indent.
Sure
+ &link_info_len)) { + p_err("Registered %s but can't find link id: %s", + bpf_map__name(map), strerror(errno)); + nr_errs++; + goto clean_link; + } + if (linkdir && pin_link(link, linkdir, info.name)) { + p_err("can't pin link %u for %s: %s", + link_info.id, info.name, + strerror(errno)); + nr_errs++; + goto clean_link; + } + p_info("Registered %s %s map id %u link id %u", + get_kern_struct_ops_name(&info), + info.name, info.id, link_info.id); + +clean_link: + bpf_link__disconnect(link); + bpf_link__destroy(link); } bpf_object__close(obj); @@ -562,7 +612,7 @@ static int do_help(int argc, char **argv) fprintf(stderr, "Usage: %1$s %2$s { show | list } [STRUCT_OPS_MAP]\n" " %1$s %2$s dump [STRUCT_OPS_MAP]\n" - " %1$s %2$s register OBJ\n" + " %1$s %2$s register OBJ [LINK_DIR]\n" " %1$s %2$s unregister STRUCT_OPS_MAP\n" " %1$s %2$s help\n" "\n" -- 2.34.1
