Linux内核学习中---有关#define LIST_HEAD_INIT(name) { &(name), &(name) }的问题

在深入学习Linux内核的过程中,遇到了#define LIST_HEAD_INIT(name) { &(name), &(name) }的定义。这段代码是用于初始化一个链表头的技巧,通过指针自指实现空链表。对于理解内核中的数据结构和编程方式至关重要。" 105284795,9397848,SQL查询技巧:SELECT运算符与条件过滤,"['SQL查询', '数据库', '数据筛选']

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最近在接触内核方面的东西,遇见如下一段代码:

struct list_head {
        struct list_head *next, *prev;        //双向链表
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }  

#define LIST_HEAD(name) \
        struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { \
        (ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)



在网上看了很多前人工作,在这里自己做下总结。

 

来看数据结构体:

struct list_head {         struct list_head *next, *prev; }; 
//宏定义如下:
#define LIST_HEAD_INIT(name) { &(name), &(name) } 
#define LIST_HEAD(name) struct list_
/* * Copyright (C) 2011-2014 MediaTek Inc. * * This program is free software: you can redistribute it and/or modify it under the terms of the * GNU General Public License version 2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along with this program. * If not, see <http://www.gnu.org/licenses/>. */ #include <linux/module.h> #include <linux/list.h> #include <linux/spinlock.h> #include "SCP_power_monitor.h" #include "scp_helper.h" static LIST_HEAD(power_monitor_list); static DEFINE_SPINLOCK(pm_lock); static atomic_t power_status = ATOMIC_INIT(SENSOR_POWER_DOWN); void scp_power_monitor_notify(uint8_t action, void *data) { struct scp_power_monitor *c; unsigned long flags; spin_lock_irqsave(&pm_lock, flags); list_for_each_entry(c, &power_monitor_list, list) { WARN_ON(c->notifier_call == NULL); c->notifier_call(action, data); pr_debug("scp_power_monitor_notify, module name:%s notify\n", c->name); } switch (action) { case SENSOR_POWER_DOWN: atomic_set(&power_status, SENSOR_POWER_DOWN); break; case SENSOR_POWER_UP: atomic_set(&power_status, SENSOR_POWER_UP); break; } spin_unlock_irqrestore(&pm_lock, flags); } int scp_power_monitor_register(struct scp_power_monitor *monitor) { int err = 0; struct scp_power_monitor *c; WARN_ON(monitor->name == NULL || monitor->notifier_call == NULL); spin_lock_irq(&pm_lock); list_for_each_entry(c, &power_monitor_list, list) { if (!strcmp(c->name, monitor->name)) { err = -1; goto out; } } list_add(&monitor->list, &power_monitor_list); if (atomic_read(&power_status) == SENSOR_POWER_UP) { pr_debug("scp_power_monitor_notify, module name:%s notify\n", monitor->name); monitor->notifier_call(SENSOR_POWER_UP, NULL); } spin_unlock_irq(&pm_lock); return err; out: pr_err("%s scp_power_monitor_register fail\n", monitor->name); spin_unlock_irq(&pm_lock); return err; } int scp_power_monitor_deregister(struct scp_power_monitor *monitor) { if (WARN_ON(list_empty(&monitor->list))) return -1; spin_lock_irq(&pm_lock); list_del(&monitor->list); spin_unlock_irq(&pm_lock); return 0; }分析代码
06-08
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