sample: bpf: syscall_tp_user: Print result of verify_map

At the end of the test, we already print out
    prog <prog number>: map ids <...> <...>
Value is the number read from kernel through bpf map, further print out
    verify map:<map id> val:<...>
will help users to understand the program runs successfully.

Signed-off-by: Song Chen <chensong_2000@189.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1648889828-12417-1-git-send-email-chensong_2000@189.cn

diff --git a/samples/bpf/syscall_tp_user.c b/samples/bpf/syscall_tp_user.c
index a0ebf1833ed37c929e14d6cd6bac8af189a8039e..c55383068384ad20e5e076a216ea670d5d6955d1 100644 (file)
--- a/samples/bpf/syscall_tp_user.c
+++ b/samples/bpf/syscall_tp_user.c
@@ -36,6 +36,9 @@ static void verify_map(int map_id)
                fprintf(stderr, "failed: map #%d returns value 0\n", map_id);
                return;
        }
+
+       printf("verify map:%d val: %d\n", map_id, val);
+
        val = 0;
        if (bpf_map_update_elem(map_id, &key, &val, BPF_ANY) != 0) {
                fprintf(stderr, "map_update failed: %s\n", strerror(errno));