On 11/19/2018 10:35 PM, Stanislav Fomichev wrote:
> Since commit 88cda1c9da02 ("bpf: libbpf: Provide basic API support
> to specify BPF obj name"), libbpf unconditionally sets bpf_attr->name
> for maps. Pre v4.14 kernels don't know about map names and return an
> error about unexpected non-zero data. Retry sys_bpf without a map
> name to cover older kernels.Looks good, small nit below: > Signed-off-by: Stanislav Fomichev <[email protected]> > --- > tools/lib/bpf/bpf.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c > index 03f9bcc4ef50..673175bc06ee 100644 > --- a/tools/lib/bpf/bpf.c > +++ b/tools/lib/bpf/bpf.c > @@ -69,6 +69,7 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr > *create_attr) > { > __u32 name_len = create_attr->name ? strlen(create_attr->name) : 0; > union bpf_attr attr; > + int ret; > > memset(&attr, '\0', sizeof(attr)); > > @@ -86,7 +87,15 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr > *create_attr) > attr.map_ifindex = create_attr->map_ifindex; > attr.inner_map_fd = create_attr->inner_map_fd; > > - return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); > + ret = sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); > + if (ret < 0 && create_attr->name) { Could you also check errno being EINVAL here so that we do not try to confuse it with an error coming from insufficient memlock which is EPERM in that case. > + /* Retry the same syscall, but without the name. > + * Pre v4.14 kernels don't support map names. > + */ > + memset(attr.map_name, 0, sizeof(attr.map_name)); > + return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); > + } > + return ret; > } > > int bpf_create_map_node(enum bpf_map_type map_type, const char *name, >
