root/tools/testing/selftests/bpf/progs/htab_update.c
// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2022. Huawei Technologies Co., Ltd */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>

char _license[] SEC("license") = "GPL";

/* Map value type: has BTF-managed field (bpf_timer) */
struct val {
        struct bpf_timer t;
        __u64 payload;
};

struct {
        __uint(type, BPF_MAP_TYPE_HASH);
        __uint(max_entries, 1);
        __type(key, __u32);
        __type(value, struct val);
} htab SEC(".maps");

int pid = 0;
int update_err = 0;

SEC("?fentry/bpf_obj_cancel_fields")
int bpf_obj_cancel_fields(void *ctx)
{
        __u32 key = 0;
        struct val value = { .payload = 1 };

        if ((bpf_get_current_pid_tgid() >> 32) != pid)
                return 0;

        update_err = bpf_map_update_elem(&htab, &key, &value, BPF_ANY);
        return 0;
}