Re: [RFC PATCH v3 21/37] bpf tools: Create eBPF maps defined in an object file

Alexei Starovoitov
2015-05-18T18:49:02Z

On 5/17/15 3:56 AM, Wang Nan wrote:
> This patch creates maps based on 'map' section in object file using
> bpf_create_map(), and store the fds into an array in
> 'struct bpf_object'. Since the byte order of the object may differ
> from the host, swap map definition before processing.
>
> This is the first patch in 'loading' phase. Previous patches parse ELF
> object file and create needed data structure, but doesnnt play with
> kernel. They belong to 'opening' phase.
>
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
...
> + for (j = 0; j < i; j++) {
> + close(obj->maps_fds[j]);
> + obj->maps_fds[j] = -1;

this line is unnecessary, since you're freeing the whole array
at the line below:

> + }
> + free(obj->maps_fds);
> + obj->maps_fds = NULL;

...

> void bpf_close_object(struct bpf_object *obj)
> {
> if (!obj)
> return;
>
> bpf_obj_clear_elf(obj);
> + bpf_unload_object(obj);

just realized that this API keeps elf file open for the whole
life time. I think that should be split up.
bpf_open_object() can do elf parsing, creation of maps and
bpf loading.
bpf_close_object() can unload programs, maps. That's fine,
but closing of elf file and freeing memory associated
with parsing sections should be a separate call.