| Message ID | 1605291013-22575-3-git-send-email-alan.maguire@oracle.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | bpf: support module BTF in btf display helpers | expand |
On Fri, Nov 13, 2020 at 10:11 AM Alan Maguire <alan.maguire@oracle.com> wrote: > > When operating on split BTF, btf__find_by_name[_kind] will not > iterate over all types since they use btf->nr_types to show > the number of types to iterate over. For split BTF this is > the number of types _on top of base BTF_, so it will > underestimate the number of types to iterate over, especially > for vmlinux + module BTF, where the latter is much smaller. > > Use btf__get_nr_types() instead. > > Signed-off-by: Alan Maguire <alan.maguire@oracle.com> > --- Good catch. I'm amazed I didn't fix it up when I implemented split BTF support, I distinctly remember looking at these two APIs... Can you please add Fixes tag and post this as a separate patch? There is no need to wait on all the other changes. Fixes: ba451366bf44 ("libbpf: Implement basic split BTF support") > tools/lib/bpf/btf.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c > index 2d0d064..0fccf4b 100644 > --- a/tools/lib/bpf/btf.c > +++ b/tools/lib/bpf/btf.c > @@ -679,7 +679,7 @@ __s32 btf__find_by_name(const struct btf *btf, const char *type_name) > if (!strcmp(type_name, "void")) > return 0; > > - for (i = 1; i <= btf->nr_types; i++) { > + for (i = 1; i <= btf__get_nr_types(btf); i++) { I think it's worthwhile to cache the result of btf__get_nr_types(btf) in a local variable instead of re-calculating it thousands of times. > const struct btf_type *t = btf__type_by_id(btf, i); > const char *name = btf__name_by_offset(btf, t->name_off); > > @@ -698,7 +698,7 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name, > if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void")) > return 0; > > - for (i = 1; i <= btf->nr_types; i++) { > + for (i = 1; i <= btf__get_nr_types(btf); i++) { same as above > const struct btf_type *t = btf__type_by_id(btf, i); > const char *name; > > -- > 1.8.3.1 >
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 2d0d064..0fccf4b 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -679,7 +679,7 @@ __s32 btf__find_by_name(const struct btf *btf, const char *type_name) if (!strcmp(type_name, "void")) return 0; - for (i = 1; i <= btf->nr_types; i++) { + for (i = 1; i <= btf__get_nr_types(btf); i++) { const struct btf_type *t = btf__type_by_id(btf, i); const char *name = btf__name_by_offset(btf, t->name_off); @@ -698,7 +698,7 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name, if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void")) return 0; - for (i = 1; i <= btf->nr_types; i++) { + for (i = 1; i <= btf__get_nr_types(btf); i++) { const struct btf_type *t = btf__type_by_id(btf, i); const char *name;
When operating on split BTF, btf__find_by_name[_kind] will not iterate over all types since they use btf->nr_types to show the number of types to iterate over. For split BTF this is the number of types _on top of base BTF_, so it will underestimate the number of types to iterate over, especially for vmlinux + module BTF, where the latter is much smaller. Use btf__get_nr_types() instead. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> --- tools/lib/bpf/btf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)