Linux内核开发环境

echo 'file svcsock.c line 1603 +p' > control # 控制打印行
echo 'func get_resources +p' > control       # 控制函数
echo "file drivers/usb/* +p" > control       # 正则表达式控制
cat batch-file > control                     # 批量控制

command ::= match-spec* flags-spec

filename:lineno [module]function flags format

awk '$3 != "=_"' control

int kobject_uevent_env(struct kobject *kobj,
                       enum kobject_action action,
                       char *envp_ext[])
{
    struct kobj_uevent_env *env =
        kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
    // 利用字符串数组将enum转换为字符串
    const char *action_string = kobject_actions[action];
    struct kobject *top_kobj = ...;             // 必须找到kset
    struct kset *kset = top_kobj->kset;
    const struct kset_uevent_ops *uevent_ops = kset->uevent_ops;
    const char *subsystem;

    if (kobj->uevent_suppress)                  // 禁止发出
        return 0;
    if (uevent_ops && uevent_ops->filter)
        if (!uevent_ops->filter(kset, kobj))    // 被过滤
            return 0;

    if (uevent_ops && uevent_ops->name)
        subsystem = uevent_ops->name(kset, kobj);
    else
        subsystem = kobject_name(&kset->kobj);
    if (!subsystem)                             // 必须有子系统
        return 0;

    const char *devpath = kobject_get_path(kobj, GFP_KERNEL);
    add_uevent_var(env, "ACTION=%s", action_string);
    add_uevent_var(env, "DEVPATH=%s", devpath);
    add_uevent_var(env, "SUBSYSTEM=%s", subsystem);
    for (int i = 0; envp_ext && envp_ext[i]; i++) // 额外环境变量
        add_uevent_var(env, "%s", envp_ext[i]);
    if (uevent_ops && uevent_ops->uevent)       // kset操作
        uevent_ops->uevent(kset, kobj, env);

    if (action == KOBJ_ADD)
        kobj->state_add_uevent_sent = 1;
    else if (action == KOBJ_REMOVE)
        kobj->state_remove_uevent_sent = 1;

    mutex_lock(&uevent_sock_mutex);
    add_uevent_var(env, "SEQNUM=%llu",          // 序列号
                   (unsigned long long)++uevent_seqnum);

#ifdef CONFIG_NET
    struct uevent_sock *ue_sk;
    list_for_each_entry(ue_sk, &uevent_sock_list, list) {
        struct sock *uevent_sock = ue_sk->sk;
        struct sk_buff *skb;
        char *scratch;
        size_t len;

        if (!netlink_has_listeners(uevent_sock, 1))
            continue;

        len = strlen(action_string) + strlen(devpath) + 2;
        skb = alloc_skb(len + env->buflen, GFP_KERNEL);

        scratch = skb_put(skb, len);
        sprintf(scratch, "%s@%s", action_string, devpath);

        for (i = 0; i < env->envp_idx; i++) {
            len = strlen(env->envp[i]) + 1;
            scratch = skb_put(skb, len);
            strcpy(scratch, env->envp[i]);
        }

        NETLINK_CB(skb).dst_group = 1;
        netlink_broadcast_filtered(uevent_sock, skb, 0, 1, GFP_KERNEL,
                                   kobj_bcast_filter, kobj);
    }
#endif
    mutex_unlock(&uevent_sock_mutex);

#ifdef CONFIG_UEVENT_HELPER
    if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
        struct subprocess_info *info;
        const char *path = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"
            add_uevent_var(env, "HOME=/");
        add_uevent_var(env, path);
        init_uevent_argv(env, subsystem);
        info = call_usermodehelper_setup(env->argv[0], env->argv,
                                         env->envp, GFP_KERNEL, NULL,
                                         cleanup_uevent_env, env);
        call_usermodehelper_exec(info, UMH_NO_WAIT);
        env = NULL;     /* freed by cleanup_uevent_env */
    }
#endif

exit:
    kfree(devpath);
    kfree(env);
    return 0;
}