| Message ID | 20181119224901.21214-1-sdf@google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf-next,v2] bpf: libbpf: retry map creation without the name | expand |
On 11/19/2018 11:49 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. > > v2 changes: > * check for errno == EINVAL as suggested by Daniel Borkmann > > Signed-off-by: Stanislav Fomichev <sdf@google.com> Applied to bpf-next, thanks!
On 11/20, Daniel Borkmann wrote: > On 11/19/2018 11:49 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. > > > > v2 changes: > > * check for errno == EINVAL as suggested by Daniel Borkmann > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > Applied to bpf-next, thanks! Great, thanks! It looks like there might be the same problem with the program's name. I'll probably follow up with another patch soon.
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 03f9bcc4ef50..961e1b9fc592 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 && errno == EINVAL && create_attr->name) { + /* 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,
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. v2 changes: * check for errno == EINVAL as suggested by Daniel Borkmann Signed-off-by: Stanislav Fomichev <sdf@google.com> --- tools/lib/bpf/bpf.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)