Re: [PATCH bpf-next v2 1/8] libbpf: Add a helper for retrieving a map fd for a given name
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2019-01-23 10:54:47
On 01/21/2019 10:10 AM, Maciej Fijalkowski wrote:
quoted hunk ↗ jump to hunk
XDP samples are mostly cooperating with eBPF maps through their file descriptors. In case of a eBPF program that contains multiple maps it might be tiresome to iterate through them and call bpf_map__fd for each one. Add a helper mostly based on bpf_object__find_map_by_name, but instead of returning the struct bpf_map pointer, return map fd. Bump libbpf ABI version to 0.0.2. Suggested-by: Jakub Kicinski <redacted> Signed-off-by: Maciej Fijalkowski <redacted> Reviewed-by: Jakub Kicinski <redacted> --- tools/lib/bpf/libbpf.c | 12 ++++++++++++ tools/lib/bpf/libbpf.h | 3 +++ tools/lib/bpf/libbpf.map | 4 ++++ 3 files changed, 19 insertions(+)diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 169e347c76f6..dc838bea403f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c@@ -2840,6 +2840,18 @@ bpf_object__find_map_by_name(struct bpf_object *obj, const char *name) return NULL; }
Application could just do: bpf_map__fd(bpf_object__find_map_by_name(...)) or bpf_object__find_map_by_name(...)->fd as both are exposed via library, though I guess it may be okay to have a helper for it as it feels this might be needed in many cases.
+int
+bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
+{
+ struct bpf_map *pos;
+
+ bpf_map__for_each(pos, obj) {
+ if (pos->name && !strcmp(pos->name, name))
+ return bpf_map__fd(pos);
+ }
+ return -ENOENT;
Can we instead just do:
int
bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
{
return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
}
quoted hunk ↗ jump to hunk
+} + struct bpf_map * bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset) {diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5f68d7b75215..7f10d36abdde 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h@@ -264,6 +264,9 @@ struct bpf_map; LIBBPF_API struct bpf_map * bpf_object__find_map_by_name(struct bpf_object *obj, const char *name); +LIBBPF_API int +bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name); + /* * Get bpf_map through the offset of corresponding struct bpf_map_def * in the BPF object file.diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index cd02cd4e2cc3..7c59e4f64082 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map@@ -124,3 +124,7 @@ LIBBPF_0.0.1 { local: *; }; +LIBBPF_0.0.2 { + global: + bpf_object__find_map_fd_by_name; +} LIBBPF_0.0.1;