[RFC bpf-next 3/5] libbpf: Pass prog_ifindex via bpf_object_open_opts

[Stanislav Fomichev <sdf@google.com>]

Allow passing prog_ifindex to BPF_PROG_LOAD. This patch is
not XDP metadata specific but it's here because we (ab)use
prog_ifindex as "target metadata" device during loading.
We can figure out proper UAPI story if we decide to go forward
with the kfunc approach.

Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/lib/bpf/libbpf.c | 1 +
 tools/lib/bpf/libbpf.h | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 5d7819edf074..61bc37006fe4 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -7190,6 +7190,7 @@ static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object
 
 		prog->type = prog->sec_def->prog_type;
 		prog->expected_attach_type = prog->sec_def->expected_attach_type;
+		prog->prog_ifindex = opts->prog_ifindex;
 
 		/* sec_def can have custom callback which should be called
 		 * after bpf_program is initialized to adjust its properties
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index eee883f007f9..4a40b7623099 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -170,9 +170,13 @@ struct bpf_object_open_opts {
 	 */
 	__u32 kernel_log_level;
 
+	/* Optional ifindex of netdev for offload purposes.
+	 */
+	int prog_ifindex;
+
 	size_t :0;
 };
-#define bpf_object_open_opts__last_field kernel_log_level
+#define bpf_object_open_opts__last_field prog_ifindex
 
 LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
 
-- 
2.38.1.273.g43a17bfeac-goog