Re: [PATCH net-next] libbpf: use map_flags when creating maps

From: Craig Gallek <redacted>

This extends struct bpf_map_def to include a flags field.  Note that
this has the potential to break the validation logic in
bpf_object__validate_maps and bpf_object__init_maps as they use
sizeof(struct bpf_map_def) as a minimal allowable size of a map section.
Any bpf program compiled with a smaller struct bpf_map_def will fail this
check.

I don't believe this will be an issue in practice as both compile-time
definitions of struct bpf_map_def (in samples/bpf/bpf_load.h and
tools/testing/selftests/bpf/bpf_helpers.h) have always been larger
than this newly updated version in libbpf.h.

Signed-off-by: Craig Gallek <redacted>
---
 tools/lib/bpf/libbpf.c | 2 +-
 tools/lib/bpf/libbpf.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 35f6dfcdc565..6bea85f260a3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c

@@ -874,7 +874,7 @@ bpf_object__create_maps(struct bpf_object *obj)
 				      def->key_size,
 				      def->value_size,
 				      def->max_entries,
-				      0);
+				      def->map_flags);
 		if (*pfd < 0) {
 			size_t j;
 			int err = *pfd;

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 7959086eb9c9..6e20003109e0 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h

@@ -207,6 +207,7 @@ struct bpf_map_def {
 	unsigned int key_size;
 	unsigned int value_size;
 	unsigned int max_entries;
+	unsigned int map_flags;
 };