Linux内核中的设计模式之全面理解与示例代码

#include <linux/sched.h>

struct task_struct *current;

void init_task_struct_singleton(void) {
    if (!current) {
        current = kmalloc(sizeof(struct task_struct), GFP_KERNEL);
        // 初始化 task_struct 的各个字段
    }
}

#include <linux/slab.h>

struct kmem_cache *my_cache;

void init_cache(void) {
    my_cache = kmem_cache_create("my_object_cache",
                                sizeof(struct my_object),
                                0, SLAB_HWCACHE_ALIGN, NULL);
}

struct my_object *create_object(void) {
    return kmem_cache_alloc(my_cache, GFP_KERNEL);
}

void destroy_object(struct my_object *obj) {
    kmem_cache_free(my_cache, obj);
}

#include <linux/notifier.h>

struct my_notifier_block {
    struct notifier_block nb;
    // 其他字段
};

int my_event_handler(struct notifier_block *nb, unsigned long val, void *data) {
    // 处理事件通知
    return NOTIFY_OK;
}

struct my_notifier_block my_notifier = {
    .nb.notifier_call = my_event_handler,
    // 初始化其他字段
};

void register_my_notifier(void) {
    register_my_notifier(&my_notifier);
}

void unregister_my_notifier(void) {
    unregister_my_notifier(&my_notifier);
}

#include <linux/sched.h>

void set_scheduler_policy(int policy) {
    struct task_struct *task = current;
    task->policy = policy;
    // 其他设置
}

#include <linux/blkdev.h>

void add_io_request(struct request_queue *q, struct request *rq) {
    blk_add_request(q, rq);
}

#include <linux/tcp.h>

struct tcp_sock {
    // 其他字段
    struct tcp_state_ops *state_ops;
};

struct tcp_state_ops {
    void (*transmit)(struct tcp_sock *sk);
    void (*receive)(struct tcp_sock *sk);
    // 其他状态相关操作
};

void tcp_transmit(struct tcp_sock *sk) {
    sk->state_ops->transmit(sk);
}

void tcp_receive(struct tcp_sock *sk) {
    sk->state_ops->receive(sk);
}

#include <linux/fs.h>

struct file_operations my_fops = {
    .open = my_driver_open,
    .read = my_driver_read,
    .write = my_driver_write,
    .release = my_driver_release,
    // 其他操作函数
};

#include <linux/fs.h>

struct dentry *my_create_file(const char *name, mode_t mode, struct dentry *parent) {
    return vfs_create_file(parent, name, &my_file_fops, NULL, mode);
}

struct dentry *my_create_directory(const char *name, struct dentry *parent) {
    return vfs_mkdir(parent->d_inode, name, 0);
}

#include <linux/sched.h>

void save_process_state(struct task_struct *task, struct task_state *state) {
    // 保存进程状态到 state 结构中
}

void restore_process_state(struct task_struct *task, struct task_state *state) {
    // 从 state 结构恢复进程状态
}

#include <linux/fs.h>

struct file_operations my_fops = {
    .read = my_driver_read,
    .write = my_driver_write,
    // 其他操作函数
};

struct file_operations another_fops = {
    .read = another_driver_read,
    .write = another_driver_write,
    // 其他操作函数
};