On Wed, Jul 13, 2022 at 2:43 PM Joe Burton <jevburton.kernel@xxxxxxxxx> wrote: > > From: Joe Burton <jevburton@xxxxxxxxxx> > > Add the capability to set a `struct bpf_map` name. > > bpf_map__reuse_fd(struct bpf_map *map, int fd) does the following: > > 1. get the bpf_map_info of the passed-in fd > 2. strdup the name from the bpf_map_info > 3. assign that name to the map > 4. and some other stuff > > While `map.name` may initially be arbitrarily long, this operation > truncates it after 15 characters. > > We have some infrastructure that uses bpf_map__reuse_fd() to preserve > maps across upgrades. Some of our users have long map names, and are > seeing their maps 'disappear' after an upgrade, due to the name > truncation. > > By invoking `bpf_map__set_name()` after `bpf_map__reuse_fd()`, we can > trivially work around the issue. Asked you internally, but not sure I follow. Can you share more on why the following won't fix it for us: https://lore.kernel.org/bpf/OSZP286MB1725CEA1C95C5CB8E7CCC53FB8869@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ ? The idea seems to be to get the supplied map name (from the obj) instead of using pin name? So why is it not enough? > Signed-off-by: Joe Burton <jevburton@xxxxxxxxxx> > --- > tools/lib/bpf/libbpf.c | 22 ++++++++++++++++++++++ > tools/lib/bpf/libbpf.h | 3 ++- > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 72548798126b..725baf508e6f 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -9089,6 +9089,28 @@ const char *bpf_map__name(const struct bpf_map *map) > return map->name; > } > > +int bpf_map__set_name(struct bpf_map *map, const char *name) > +{ > + char *new_name; > + > + if (!map) > + return libbpf_err(-EINVAL); > + > + new_name = strdup(name); > + if (!new_name) > + return libbpf_err(-ENOMEM); > + > + if (map_uses_real_name(map)) { > + free(map->real_name); > + map->real_name = new_name; > + } else { > + free(map->name); > + map->name = new_name; > + } > + > + return 0; > +} > + > enum bpf_map_type bpf_map__type(const struct bpf_map *map) > { > return map->def.type; > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index e4d5353f757b..e898c4cb514a 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -731,8 +731,9 @@ LIBBPF_API bool bpf_map__autocreate(const struct bpf_map *map); > */ > LIBBPF_API int bpf_map__fd(const struct bpf_map *map); > LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); > -/* get map name */ > +/* get/set map name */ > LIBBPF_API const char *bpf_map__name(const struct bpf_map *map); > +LIBBPF_API int bpf_map__set_name(struct bpf_map *map, const char *name); > /* get/set map type */ > LIBBPF_API enum bpf_map_type bpf_map__type(const struct bpf_map *map); > LIBBPF_API int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type); > -- > 2.37.0.144.g8ac04bfd2-goog >
