Re: [PATCH bpf-next] libbpf: export bpf_object__reuse_map() to libbpf api
From: Andrii Nakryiko <hidden>
Date: 2020-09-29 03:30:55
Also in:
bpf
On Mon, Sep 28, 2020 at 8:20 PM Hangbin Liu [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Besides bpf_map__reuse_fd(), which could let us reuse existing map fd. bpf_object__reuse_map() could let us reuse existing pinned maps, which is helpful. This functions could also be used when we add iproute2 libbpf support, so we don't need to re-use or re-implement new functions like bpf_obj_get()/bpf_map_selfcheck_pinned() in iproute2. Signed-off-by: Hangbin Liu <redacted> --- tools/lib/bpf/libbpf.c | 3 +-- tools/lib/bpf/libbpf.h | 1 + 2 files changed, 2 insertions(+), 2 deletions(-)diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 32dc444224d8..e835d7a3437f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c@@ -4033,8 +4033,7 @@ static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd) map_info.map_flags == map->def.map_flags); } -static int -bpf_object__reuse_map(struct bpf_map *map) +int bpf_object__reuse_map(struct bpf_map *map) { char *cp, errmsg[STRERR_BUFSIZE]; int err, pin_fd;diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index a750f67a23f6..4b9e615eb393 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h@@ -431,6 +431,7 @@ bpf_map__prev(const struct bpf_map *map, const struct bpf_object *obj); /* get/set map FD */ LIBBPF_API int bpf_map__fd(const struct bpf_map *map); LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); +LIBBPF_API int bpf_object__reuse_map(struct bpf_map *map);
It's internal function, which doesn't check that map->pin_path is set, for one thing. It shouldn't be exposed. libbpf exposes bpf_map__set_pin_path() to set pin_path for any map, and then during load time libbpf with "reuse map", if pin_path is not NULL. Doesn't that work for you?
/* get map definition */ LIBBPF_API const struct bpf_map_def *bpf_map__def(const struct bpf_map *map); /* get map name */ -- 2.25.4