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Message-ID: <CAEf4BzZBjVw4ptGZE8V9SM4htW_Nf_TjXkUKEHjF9bxgO43DQA@mail.gmail.com>
Date: Tue, 17 Nov 2020 18:52:29 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: "Daniel T. Lee" <danieltimlee@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
Andrii Nakryiko <andrii@...nel.org>, brakmo <brakmo@...com>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Lorenzo Bianconi <lorenzo@...nel.org>,
David Ahern <dsa@...ulusnetworks.com>,
Yonghong Song <yhs@...com>,
Toke Høiland-Jørgensen <toke@...hat.com>,
Ira Weiny <ira.weiny@...el.com>, Thomas Graf <tgraf@...g.ch>,
Jakub Kicinski <kuba@...nel.org>,
Martin KaFai Lau <kafai@...com>,
John Fastabend <john.fastabend@...il.com>,
bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
Xdp <xdp-newbies@...r.kernel.org>
Subject: Re: [PATCH bpf-next 5/9] samples: bpf: refactor ibumad program with libbpf
On Tue, Nov 17, 2020 at 6:57 AM Daniel T. Lee <danieltimlee@...il.com> wrote:
>
> This commit refactors the existing ibumad program with libbpf bpf
> loader. Attach/detach of Tracepoint bpf programs has been managed
> with the generic bpf_program__attach() and bpf_link__destroy() from
> the libbpf.
>
> Also, instead of using the previous BPF MAP definition, this commit
> refactors ibumad MAP definition with the new BTF-defined MAP format.
>
> To verify that this bpf program works without an infiniband device,
> try loading ib_umad kernel module and test the program as follows:
>
> # modprobe ib_umad
> # ./ibumad
>
> Moreover, TRACE_HELPERS has been removed from the Makefile since it is
> not used on this program.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
> ---
> samples/bpf/Makefile | 2 +-
> samples/bpf/ibumad_kern.c | 26 +++++++--------
> samples/bpf/ibumad_user.c | 66 ++++++++++++++++++++++++++++++---------
> 3 files changed, 65 insertions(+), 29 deletions(-)
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 36b261c7afc7..bfa595379493 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -109,7 +109,7 @@ xsk_fwd-objs := xsk_fwd.o
> xdp_fwd-objs := xdp_fwd_user.o
> task_fd_query-objs := task_fd_query_user.o $(TRACE_HELPERS)
> xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
> -ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
> +ibumad-objs := ibumad_user.o
> hbm-objs := hbm.o $(CGROUP_HELPERS) $(TRACE_HELPERS)
>
> # Tell kbuild to always build the programs
> diff --git a/samples/bpf/ibumad_kern.c b/samples/bpf/ibumad_kern.c
> index 3a91b4c1989a..26dcd4dde946 100644
> --- a/samples/bpf/ibumad_kern.c
> +++ b/samples/bpf/ibumad_kern.c
> @@ -16,19 +16,19 @@
> #include <bpf/bpf_helpers.h>
>
>
> -struct bpf_map_def SEC("maps") read_count = {
> - .type = BPF_MAP_TYPE_ARRAY,
> - .key_size = sizeof(u32), /* class; u32 required */
> - .value_size = sizeof(u64), /* count of mads read */
> - .max_entries = 256, /* Room for all Classes */
> -};
> -
> -struct bpf_map_def SEC("maps") write_count = {
> - .type = BPF_MAP_TYPE_ARRAY,
> - .key_size = sizeof(u32), /* class; u32 required */
> - .value_size = sizeof(u64), /* count of mads written */
> - .max_entries = 256, /* Room for all Classes */
> -};
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __type(key, u32); /* class; u32 required */
> + __type(value, u64); /* count of mads read */
> + __uint(max_entries, 256); /* Room for all Classes */
> +} read_count SEC(".maps");
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __type(key, u32); /* class; u32 required */
> + __type(value, u64); /* count of mads written */
> + __uint(max_entries, 256); /* Room for all Classes */
> +} write_count SEC(".maps");
>
> #undef DEBUG
> #ifndef DEBUG
> diff --git a/samples/bpf/ibumad_user.c b/samples/bpf/ibumad_user.c
> index fa06eef31a84..66a06272f242 100644
> --- a/samples/bpf/ibumad_user.c
> +++ b/samples/bpf/ibumad_user.c
> @@ -23,10 +23,15 @@
> #include <getopt.h>
> #include <net/if.h>
>
> -#include "bpf_load.h"
> +#include <bpf/bpf.h>
> #include "bpf_util.h"
> #include <bpf/libbpf.h>
>
> +struct bpf_link *tp_links[3] = {};
> +struct bpf_object *obj;
statics and you can drop = {} part.
> +static int map_fd[2];
> +static int tp_cnt;
> +
> static void dump_counts(int fd)
> {
> __u32 key;
> @@ -53,6 +58,11 @@ static void dump_all_counts(void)
> static void dump_exit(int sig)
> {
> dump_all_counts();
> + /* Detach tracepoints */
> + while (tp_cnt)
> + bpf_link__destroy(tp_links[--tp_cnt]);
> +
> + bpf_object__close(obj);
> exit(0);
> }
>
> @@ -73,19 +83,11 @@ static void usage(char *cmd)
>
> int main(int argc, char **argv)
> {
> + struct bpf_program *prog;
> unsigned long delay = 5;
> + char filename[256];
> int longindex = 0;
> int opt;
> - char bpf_file[256];
> -
> - /* Create the eBPF kernel code path name.
> - * This follows the pattern of all of the other bpf samples
> - */
> - snprintf(bpf_file, sizeof(bpf_file), "%s_kern.o", argv[0]);
> -
> - /* Do one final dump when exiting */
> - signal(SIGINT, dump_exit);
> - signal(SIGTERM, dump_exit);
>
> while ((opt = getopt_long(argc, argv, "hd:rSw",
> long_options, &longindex)) != -1) {
> @@ -107,10 +109,38 @@ int main(int argc, char **argv)
> }
> }
>
> - if (load_bpf_file(bpf_file)) {
> - fprintf(stderr, "ERROR: failed to load eBPF from file : %s\n",
> - bpf_file);
> - return 1;
> + /* Do one final dump when exiting */
> + signal(SIGINT, dump_exit);
> + signal(SIGTERM, dump_exit);
> +
> + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
> + obj = bpf_object__open_file(filename, NULL);
> + if (libbpf_get_error(obj)) {
> + fprintf(stderr, "ERROR: opening BPF object file failed\n");
> + return 0;
not really a success, no?
> + }
> +
> + /* load BPF program */
> + if (bpf_object__load(obj)) {
> + fprintf(stderr, "ERROR: loading BPF object file failed\n");
> + goto cleanup;
> + }
> +
> + map_fd[0] = bpf_object__find_map_fd_by_name(obj, "read_count");
> + map_fd[1] = bpf_object__find_map_fd_by_name(obj, "write_count");
> + if (map_fd[0] < 0 || map_fd[1] < 0) {
> + fprintf(stderr, "ERROR: finding a map in obj file failed\n");
> + goto cleanup;
> + }
> +
> + bpf_object__for_each_program(prog, obj) {
> + tp_links[tp_cnt] = bpf_program__attach(prog);
> + if (libbpf_get_error(tp_links[tp_cnt])) {
> + fprintf(stderr, "ERROR: bpf_program__attach failed\n");
> + tp_links[tp_cnt] = NULL;
> + goto cleanup;
> + }
> + tp_cnt++;
> }
This cries for the BPF skeleton... But one step at a time :)
>
> while (1) {
> @@ -118,5 +148,11 @@ int main(int argc, char **argv)
> dump_all_counts();
> }
>
> +cleanup:
> + /* Detach tracepoints */
> + while (tp_cnt)
> + bpf_link__destroy(tp_links[--tp_cnt]);
> +
> + bpf_object__close(obj);
> return 0;
same, in a lot of cases it's not a success, probably need int err
variable somewhere.
> }
> --
> 2.25.1
>
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