tools lib bpf: Add bpf_object__pin()

Add a new API to pin a BPF object to the filesystem. The user can
specify the path within a BPF filesystem to pin the object.
Programs will be pinned under a subdirectory named the same as the
program, with each instance appearing as a numbered file under that
directory, and maps will be pinned under the path using the name of
the map as the file basename.

For example, with the directory '/sys/fs/bpf/foo' and a BPF object which
contains two instances of a program named 'bar', and a map named 'baz':

/sys/fs/bpf/foo/bar/0
/sys/fs/bpf/foo/bar/1
/sys/fs/bpf/foo/baz

Signed-off-by: Joe Stringer <joe@ovn.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20170126212001.14103-4-joe@ovn.org
[ Check snprintf >= for truncation, as snprintf(bf, size, ...) == size also means truncation ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6a8c8beeb291921dd79a4782a8c66c23d58c3efd..ac6eb863b2a40df00c4ead9f48c872ab67949c19 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1379,6 +1379,59 @@ int bpf_map__pin(struct bpf_map *map, const char *path)
        return 0;
 }
 
+int bpf_object__pin(struct bpf_object *obj, const char *path)
+{
+       struct bpf_program *prog;
+       struct bpf_map *map;
+       int err;
+
+       if (!obj)
+               return -ENOENT;
+
+       if (!obj->loaded) {
+               pr_warning("object not yet loaded; load it first\n");
+               return -ENOENT;
+       }
+
+       err = make_dir(path);
+       if (err)
+               return err;
+
+       bpf_map__for_each(map, obj) {
+               char buf[PATH_MAX];
+               int len;
+
+               len = snprintf(buf, PATH_MAX, "%s/%s", path,
+                              bpf_map__name(map));
+               if (len < 0)
+                       return -EINVAL;
+               else if (len >= PATH_MAX)
+                       return -ENAMETOOLONG;
+
+               err = bpf_map__pin(map, buf);
+               if (err)
+                       return err;
+       }
+
+       bpf_object__for_each_program(prog, obj) {
+               char buf[PATH_MAX];
+               int len;
+
+               len = snprintf(buf, PATH_MAX, "%s/%s", path,
+                              prog->section_name);
+               if (len < 0)
+                       return -EINVAL;
+               else if (len >= PATH_MAX)
+                       return -ENAMETOOLONG;
+
+               err = bpf_program__pin(prog, buf);
+               if (err)
+                       return err;
+       }
+
+       return 0;
+}
+
 void bpf_object__close(struct bpf_object *obj)
 {
        size_t i;

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 2addf9d5b13cdf6d039e2e3a7058a45a9d3a1a83..b30394f9947a35356af870223664a4409f8e5fd6 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -65,6 +65,7 @@ struct bpf_object *bpf_object__open(const char *path);
 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
                                           size_t obj_buf_sz,
                                           const char *name);
+int bpf_object__pin(struct bpf_object *object, const char *path);
 void bpf_object__close(struct bpf_object *object);
 
 /* Load/unload object into/from kernel */