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SubjectRe: [PATCH 5/8] tools lib bpf: add missing functions
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On 2016/10/17 5:18, Eric Leblond wrote:
> Some functions were missing in the library to be able to use it
> in the case where the userspace is handling the maps in kernel.
>
> The patch also renames functions to have a homogeneous naming
> convention.
>
> Signed-off-by: Eric Leblond <eric@regit.org>
> ---
> tools/lib/bpf/bpf.c | 35 ++++++++++++++++++++++++++++++++++-
> tools/lib/bpf/bpf.h | 2 --
> tools/lib/bpf/libbpf.h | 5 +++++
> 3 files changed, 39 insertions(+), 3 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 4212ed6..c0e07bd 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -25,6 +25,7 @@
> #include <asm/unistd.h>
> #include <linux/bpf.h>
> #include "bpf.h"
> +#include "libbpf.h"
>
> /*
> * When building perf, unistd.h is overrided. __NR_bpf is
> @@ -97,7 +98,7 @@ int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
> return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
> }
>
> -int bpf_map_update_elem(int fd, void *key, void *value,
> +int bpf_map__update_elem(int fd, void *key, void *value,
> u64 flags)

Please don't use '__' style API here. It is easily be confused with
bpf_map__*() in libbpf.h. They are APIs at different level.

bpf_map__*() are APIs for 'struct bpf_map's, they are object introduced
by libbpf, defined in libbpf.h. bpf_map_*() APIs operate on fd, they are
objects defined by kernel. bpf_map_*() APIs are declared in bpf.h.

In libbpf, bpf.h directly operates on kernel objects (fd), APIs in it
are named bpf_map_*(); libbpf.h operates on 'struct bpf_map' object,
APIs in it are named using bpf_map__*(). libbpf.h and bpf.h are independent
with each other.

> {
> union bpf_attr attr;
> @@ -110,3 +111,35 @@ int bpf_map_update_elem(int fd, void *key, void *value,
>
> return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
> }
> +
> +int bpf_map__lookup_elem(int fd, void *key, void *value)
> +{
> + union bpf_attr attr = {
> + .map_fd = fd,
> + .key = ptr_to_u64(key),
> + .value = ptr_to_u64(value),
> + };
> +
> + return sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
> +}
> +
> +int bpf_map__delete_elem(int fd, void *key)
> +{
> + union bpf_attr attr = {
> + .map_fd = fd,
> + .key = ptr_to_u64(key),
> + };
> +
> + return sys_bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
> +}
> +
> +int bpf_map__get_next_key(int fd, void *key, void *next_key)
> +{
> + union bpf_attr attr = {
> + .map_fd = fd,
> + .key = ptr_to_u64(key),
> + .next_key = ptr_to_u64(next_key),
> + };
> +
> + return sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
> +}
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index e8ba540..5ca834a 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -33,6 +33,4 @@ int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
> u32 kern_version, char *log_buf,
> size_t log_buf_sz);
>
> -int bpf_map_update_elem(int fd, void *key, void *value,
> - u64 flags);
> #endif
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index a18783b..dfb46d0 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -207,6 +207,11 @@ bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
> int bpf_map__fd(struct bpf_map *map);
> const struct bpf_map_def *bpf_map__def(struct bpf_map *map);
> const char *bpf_map__name(struct bpf_map *map);
> +int bpf_map__update_elem(int fd, void *key, void *value,
> + uint64_t flags);
> +int bpf_map__lookup_elem(int fd, void *key, void *value);
> +int bpf_map__delete_elem(int fd, void *key);
> +int bpf_map__get_next_key(int fd, void *key, void *next_key);

As what we have discussed, the newly introduced functions should be added
in bpf.h.

Thank you.

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