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SubjectRe: [bpf-next 1/2] libbpf: Add make_path_and_pin() helper for bpf_xxx__pin()
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On 09/09, Wang Yufen wrote:
> Move make path, check path and pin to the common helper
> make_path_and_pin() to make
> the code simpler.

Idk, I guess I'll defer to Andrii here; I won't really call it simpler.
The code just looks different and looses some observability (see below).

> Signed-off-by: Wang Yufen <wangyufen@huawei.com>
> ---
> tools/lib/bpf/libbpf.c | 56
> ++++++++++++++++++++++----------------------------
> 1 file changed, 24 insertions(+), 32 deletions(-)

> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 3ad1392..5854b92 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -7755,16 +7755,11 @@ static int check_path(const char *path)
> return err;
> }

> -int bpf_program__pin(struct bpf_program *prog, const char *path)
> +static int make_path_and_pin(int fd, const char *path)
> {
> char *cp, errmsg[STRERR_BUFSIZE];
> int err;

> - if (prog->fd < 0) {
> - pr_warn("prog '%s': can't pin program that wasn't loaded\n",
> prog->name);
> - return libbpf_err(-EINVAL);
> - }
> -
> err = make_parent_dir(path);
> if (err)
> return libbpf_err(err);
> @@ -7773,12 +7768,27 @@ int bpf_program__pin(struct bpf_program *prog,
> const char *path)
> if (err)
> return libbpf_err(err);

> - if (bpf_obj_pin(prog->fd, path)) {
> + if (bpf_obj_pin(fd, path)) {
> err = -errno;
> cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
> - pr_warn("prog '%s': failed to pin at '%s': %s\n", prog->name, path,
> cp);
> + pr_warn("failed to pin at '%s': %s\n", path, cp);

This seems to be making logging worse?
We went from "can't pin 'program name' to 'path': ENOENT" to "can't pin
to 'path': ENOENT". You can deduce the program name from the path, but
why not keep the proper log message?

> return libbpf_err(err);
> }
> + return 0;
> +}
> +
> +int bpf_program__pin(struct bpf_program *prog, const char *path)
> +{
> + int err;
> +
> + if (prog->fd < 0) {
> + pr_warn("prog '%s': can't pin program that wasn't loaded\n",
> prog->name);
> + return libbpf_err(-EINVAL);
> + }
> +
> + err = make_path_and_pin(prog->fd, path);
> + if (err)
> + return libbpf_err(err);

> pr_debug("prog '%s': pinned at '%s'\n", prog->name, path);
> return 0;
> @@ -7838,32 +7848,20 @@ int bpf_map__pin(struct bpf_map *map, const char
> *path)
> map->pin_path = strdup(path);
> if (!map->pin_path) {
> err = -errno;
> - goto out_err;
> + cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
> + pr_warn("failed to pin map: %s\n", cp);
> + return libbpf_err(err);
> }
> }

> - err = make_parent_dir(map->pin_path);
> - if (err)
> - return libbpf_err(err);
> -
> - err = check_path(map->pin_path);
> + err = make_path_and_pin(map->fd, map->pin_path);
> if (err)
> return libbpf_err(err);

> - if (bpf_obj_pin(map->fd, map->pin_path)) {
> - err = -errno;
> - goto out_err;
> - }
> -
> map->pinned = true;
> pr_debug("pinned map '%s'\n", map->pin_path);

> return 0;
> -
> -out_err:
> - cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
> - pr_warn("failed to pin map: %s\n", cp);
> - return libbpf_err(err);
> }

> int bpf_map__unpin(struct bpf_map *map, const char *path)
> @@ -9611,19 +9609,13 @@ int bpf_link__pin(struct bpf_link *link, const
> char *path)

> if (link->pin_path)
> return libbpf_err(-EBUSY);
> - err = make_parent_dir(path);
> - if (err)
> - return libbpf_err(err);
> - err = check_path(path);
> - if (err)
> - return libbpf_err(err);

> link->pin_path = strdup(path);
> if (!link->pin_path)
> return libbpf_err(-ENOMEM);

> - if (bpf_obj_pin(link->fd, link->pin_path)) {
> - err = -errno;
> + err = make_path_and_pin(link->fd, path);
> + if (err) {
> zfree(&link->pin_path);
> return libbpf_err(err);
> }
> --
> 1.8.3.1

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