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SubjectRe: [PATCH 06/39] bpf tools: Create eBPF maps defined in an object file


On 2015/7/14 3:54, Arnaldo Carvalho de Melo wrote:
> Em Thu, Jul 09, 2015 at 12:35:09PM +0000, Wang Nan escreveu:
>
> <SNIP>
>
>> +static int
>> +bpf_object__create_maps(struct bpf_object *obj)
>> +{
>> + unsigned int i;
>> + size_t nr_maps;
>> + int *pfd;
>> +
>> + nr_maps = obj->maps_buf_sz / sizeof(struct bpf_map_def);
>> + if (!obj->maps_buf || !nr_maps) {
>> + pr_debug("don't need create maps for %s\n",
>> + obj->path);
>> + return 0;
>> + }
>> +
>> + obj->map_fds = malloc(sizeof(int) * nr_maps);
>> + if (!obj->map_fds) {
>> + pr_warning("realloc perf_bpf_map_fds failed\n");
>> + return -ENOMEM;
>> + }
>> + obj->nr_map_fds = nr_maps;
>> +
>> + /* fill all fd with -1 */
>> + memset(obj->map_fds, 0xff, sizeof(int) * nr_maps);
> Huh? Each entry is an int... If you want to set it all to -1, why don't
> you do it as:
>
> memset(obj->map_fds, -1, sizeof(int) * nr_maps);
>
> That way we can even remove that comment :) Doing it, please let me know
> if this has some magic twist that makes it be right as-is, if so, please
> provide a better comment.

Yes, it should be better.

Thank you,

> - Arnaldo
>
>> +
>> + pfd = obj->map_fds;
>> + for (i = 0; i < nr_maps; i++) {
>> + struct bpf_map_def def;
>> +
>> + def = *(struct bpf_map_def *)(obj->maps_buf +
>> + i * sizeof(struct bpf_map_def));
>> +
>> + *pfd = bpf_create_map(def.type,
>> + def.key_size,
>> + def.value_size,
>> + def.max_entries);
>> + if (*pfd < 0) {
>> + size_t j;
>> + int err = *pfd;
>> +
>> + pr_warning("failed to create map: %s\n",
>> + strerror(errno));
>> + for (j = 0; j < i; j++)
>> + zclose(obj->map_fds[j]);
>> + obj->nr_map_fds = 0;
>> + zfree(&obj->map_fds);
>> + return err;
>> + }
>> + pr_debug("create map: fd=%d\n", *pfd);
>> + pfd++;
>> + }
>> +
>> + zfree(&obj->maps_buf);
>> + obj->maps_buf_sz = 0;
>> + return 0;
>> +}
>> +
>> static int bpf_object__collect_reloc(struct bpf_object *obj)
>> {
>> int i, err;
>> @@ -671,6 +736,42 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf,
>> return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz);
>> }
>>
>> +int bpf_object__unload(struct bpf_object *obj)
>> +{
>> + size_t i;
>> +
>> + if (!obj)
>> + return -EINVAL;
>> +
>> + for (i = 0; i < obj->nr_map_fds; i++)
>> + zclose(obj->map_fds[i]);
>> + zfree(&obj->map_fds);
>> + obj->nr_map_fds = 0;
>> +
>> + return 0;
>> +}
>> +
>> +int bpf_object__load(struct bpf_object *obj)
>> +{
>> + if (!obj)
>> + return -EINVAL;
>> +
>> + if (obj->loaded) {
>> + pr_warning("object should not be loaded twice\n");
>> + return -EINVAL;
>> + }
>> +
>> + obj->loaded = true;
>> + if (bpf_object__create_maps(obj))
>> + goto out;
>> +
>> + return 0;
>> +out:
>> + bpf_object__unload(obj);
>> + pr_warning("failed to load object '%s'\n", obj->path);
>> + return -EINVAL;
>> +}
>> +
>> void bpf_object__close(struct bpf_object *obj)
>> {
>> size_t i;
>> @@ -679,6 +780,7 @@ void bpf_object__close(struct bpf_object *obj)
>> return;
>>
>> bpf_object__elf_finish(obj);
>> + bpf_object__unload(obj);
>>
>> zfree(&obj->maps_buf);
>>
>> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
>> index 6e75acd..3e69600 100644
>> --- a/tools/lib/bpf/libbpf.h
>> +++ b/tools/lib/bpf/libbpf.h
>> @@ -30,6 +30,10 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf,
>> size_t obj_buf_sz);
>> void bpf_object__close(struct bpf_object *object);
>>
>> +/* Load/unload object into/from kernel */
>> +int bpf_object__load(struct bpf_object *obj);
>> +int bpf_object__unload(struct bpf_object *obj);
>> +
>> /*
>> * We don't need __attribute__((packed)) now since it is
>> * unnecessary for 'bpf_map_def' because they are all aligned.
>> --
>> 1.8.3.4




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