On 7/27/21 6:49 AM, Andrii Nakryiko wrote: > On Fri, Jul 23, 2021 at 10:13 PM Hengqi Chen <hengqi.chen@xxxxxxxxx> wrote: >> >> Add libbpf_load_vmlinux_btf/libbpf_load_module_btf APIs. >> This is part of the libbpf v1.0. [1] >> >> [1] https://github.com/libbpf/libbpf/issues/280 > > Saying it's part of libbpf 1.0 effort and given a link to Github PR is > not really a sufficient commit message. Please expand on what you are > doing in the patch and why. > Will do. >> >> Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx> >> --- >> tools/lib/bpf/btf.c | 24 +++++++++++++++++++++++- >> tools/lib/bpf/btf.h | 2 ++ >> tools/lib/bpf/libbpf.c | 8 ++++---- >> tools/lib/bpf/libbpf.map | 2 ++ >> 4 files changed, 31 insertions(+), 5 deletions(-) >> >> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c >> index b46760b93bb4..414e1c5635ef 100644 >> --- a/tools/lib/bpf/btf.c >> +++ b/tools/lib/bpf/btf.c >> @@ -4021,7 +4021,7 @@ static void btf_dedup_merge_hypot_map(struct btf_dedup *d) >> */ >> if (d->hypot_adjust_canon) >> continue; >> - >> + >> if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD) >> d->map[t_id] = c_id; >> >> @@ -4395,6 +4395,11 @@ static int btf_dedup_remap_types(struct btf_dedup *d) >> * data out of it to use for target BTF. >> */ >> struct btf *libbpf_find_kernel_btf(void) >> +{ >> + return libbpf_load_vmlinux_btf(); >> +} >> + >> +struct btf *libbpf_load_vmlinux_btf(void) >> { >> struct { >> const char *path_fmt; >> @@ -4440,6 +4445,23 @@ struct btf *libbpf_find_kernel_btf(void) >> return libbpf_err_ptr(-ESRCH); >> } >> >> +struct btf *libbpf_load_module_btf(const char *mod) > > So we probably need to allow user to pre-load and re-use vmlinux BTF > for efficiency, especially if they have some use-case to load a lot of > BTFs. > Should the API change to this ? struct btf *libbpf_load_module_btf(struct btf *base, const char *mod) It seems better for the use-case you mentioned. >> +{ >> + char path[80]; >> + struct btf *base; >> + int err; >> + >> + base = libbpf_load_vmlinux_btf(); >> + err = libbpf_get_error(base); >> + if (err) { >> + pr_warn("Error loading vmlinux BTF: %d\n", err); >> + return base; > > libbpf_err_ptr() needs to be used here, pr_warn() could have destroyed > errno already > OK. >> + } >> + >> + snprintf(path, sizeof(path), "/sys/kernel/btf/%s", mod); >> + return btf__parse_split(path, base); > > so who's freeing base BTF in this case? > Sorry, missed that. But if we change the signature, then leave this to user. >> +} >> + >> int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx) >> { >> int i, n, err; > > [...] >
