Binder(2)

1.binder_init

device_initcall(binder_init);

 static int __init binder_init(void)
{
	int ret;
	char *device_name, *device_names, *device_tmp;
	struct binder_device *device;
	struct hlist_node *tmp;

	ret = binder_alloc_shrinker_init();
	if (ret)
		return ret;

	atomic_set(&binder_transaction_log.cur, ~0U);
	atomic_set(&binder_transaction_log_failed.cur, ~0U);

	binder_debugfs_dir_entry_root = debugfs_create_dir("binder", NULL);
	if (binder_debugfs_dir_entry_root)
		binder_debugfs_dir_entry_proc = debugfs_create_dir("proc",
						 binder_debugfs_dir_entry_root);

	if (binder_debugfs_dir_entry_root) {
		debugfs_create_file("state",
				    0444,
				    binder_debugfs_dir_entry_root,
				    NULL,
				    &binder_state_fops);
		debugfs_create_file("stats",
				    0444,
				    binder_debugfs_dir_entry_root,
				    NULL,
				    &binder_stats_fops);
		debugfs_create_file("transactions",
				    0444,
				    binder_debugfs_dir_entry_root,
				    NULL,
				    &binder_transactions_fops);
		debugfs_create_file("transaction_log",
				    0444,
				    binder_debugfs_dir_entry_root,
				    &binder_transaction_log,
				    &binder_transaction_log_fops);
		debugfs_create_file("failed_transaction_log",
				    0444,
				    binder_debugfs_dir_entry_root,
				    &binder_transaction_log_failed,
				    &binder_transaction_log_fops);
	}

	/*
	 * Copy the module_parameter string, because we don't want to
	 * tokenize it in-place.
	 */
	device_names = kzalloc(strlen(binder_devices_param) + 1, GFP_KERNEL);
	if (!device_names) {
		ret = -ENOMEM;
		goto err_alloc_device_names_failed;
	}
	strcpy(device_names, binder_devices_param);

	device_tmp = device_names;
	while ((device_name = strsep(&device_tmp, ","))) {
		ret = init_binder_device(device_name);
		if (ret)
			goto err_init_binder_device_failed;
	}

#ifdef CONFIG_MILLET
	register_millet_hook(BINDER_TYPE, NULL,
			binder_sendmsg, binder_init_millet);
	register_millet_hook(BINDER_ST_TYPE, binder_recv_hook,
			binder_st_sendmsg, binder_st_init_millet);
#endif
	return ret;

err_init_binder_device_failed:
	hlist_for_each_entry_safe(device, tmp, &binder_devices, hlist) {
		misc_deregister(&device->miscdev);
		hlist_del(&device->hlist);
		kfree(device);
	}

	kfree(device_names);

err_alloc_device_names_failed:
	debugfs_remove_recursive(binder_debugfs_dir_entry_root);

	return ret;
}

binder_devices_param　＝　CONFIG_ANDROID_BINDER_DEVICES=“binder,hwbinder,vndbinder” 创建3个设备

	ret = init_binder_device(device_name);

static int __init init_binder_device(const char *name)
{
	int ret;
	struct binder_device *binder_device;

	binder_device = kzalloc(sizeof(*binder_device), GFP_KERNEL);
	if (!binder_device)
		return -ENOMEM;

	binder_device->miscdev.fops = &binder_fops;　　//一些操作函数
	binder_device->miscdev.minor = MISC_DYNAMIC_MINOR;
	binder_device->miscdev.name = name;

	binder_device->context.binder_context_mgr_uid = INVALID_UID;
	binder_device->context.name = name;
	mutex_init(&binder_device->context.context_mgr_node_lock);

	ret = misc_register(&binder_device->miscdev);
	if (ret < 0) {
		kfree(binder_device);
		return ret;
	}

	hlist_add_head(&binder_device->hlist, &binder_devices);

	return ret;
}

binder_device创建，然后注册misc设备
ret = misc_register(&binder_device->miscdev);
hlist_add_head(&binder_device->hlist, &binder_devices);

关注一下其中的结构体：

struct binder_device {
	struct hlist_node hlist;
	struct miscdevice miscdev;
	struct binder_context context;
};


struct miscdevice  {
	int minor;　　//次设备号
	const char *name;
	const struct file_operations *fops;
	struct list_head list;
	struct device *parent;
	struct device *this_device;
	const struct attribute_group **groups;
	const char *nodename;
	umode_t mode;
};

2.binder_open()

open("/dev/hwbinder", O_RDWR | O_CLOEXEC);
通过name来找到设备，调用binder_open

servicemanager
processstate创建时，调用，
mDriverFD(open_driver()),然后调用binder_open

进程调用binder方式：

struct binder_state *binder_open(const char* driver, size_t mapsize)
{
    struct binder_state *bs;
    struct binder_version vers;

    bs = malloc(sizeof(*bs));
    if (!bs) {
        errno = ENOMEM;
        return NULL;
    }

    bs->fd = open(driver, O_RDWR | O_CLOEXEC);　　//打开/dev/binder调用binder_open
    if (bs->fd < 0) {
        fprintf(stderr,"binder: cannot open %s (%s)\n",
                driver, strerror(errno));
        goto fail_open;
    }

    if ((ioctl(bs->fd, BINDER_VERSION, &vers) == -1) ||　　 //获得版本信息
        (vers.protocol_version != BINDER_CURRENT_PROTOCOL_VERSION)) {
        fprintf(stderr,
                "binder: kernel driver version (%d) differs from user space version (%d)\n",
                vers.protocol_version, BINDER_CURRENT_PROTOCOL_VERSION);
        goto fail_open;
    }

    bs->mapsize = mapsize;
    bs->mapped = mmap(NULL, mapsize, PROT_READ, MAP_PRIVATE, bs->fd, 0);//申请128K内存空间，为servicemanager使用，binder服务进程映射的为1M-8K内存。
    if (bs->mapped == MAP_FAILED) {
        fprintf(stderr,"binder: cannot map device (%s)\n",
                strerror(errno));
        goto fail_map;
    }

    return bs;

fail_map:
    close(bs->fd);
fail_open:
    free(bs);
    return NULL;
}

binder_open

static int binder_open(struct inode *nodp, struct file *filp)
{
	struct binder_proc *proc;
	struct binder_device *binder_dev;

	binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d:%d\n", __func__,
		     current->group_leader->pid, current->pid);

	proc = kzalloc(sizeof(*proc), GFP_KERNEL);
	if (proc == NULL)
		return -ENOMEM;
	spin_lock_init(&proc->inner_lock);
	spin_lock_init(&proc->outer_lock);
	get_task_struct(current->group_leader);
	proc->tsk = current->group_leader;
	mutex_init(&proc->files_lock);
	INIT_LIST_HEAD(&proc->todo);
	if (binder_supported_policy(current->policy)) {
		proc->default_priority.sched_policy = current->policy;
		proc->default_priority.prio = current->normal_prio;
	} else {
		proc->default_priority.sched_policy = SCHED_NORMAL;
		proc->default_priority.prio = NICE_TO_PRIO(0);
	}

	
	 = container_of(filp->private_data, struct binder_device,
				  miscdev);
	proc->context = &binder_dev->context;
	binder_alloc_init(&proc->alloc);

	binder_stats_created(BINDER_STAT_PROC);
	proc->pid = current->group_leader->pid;
	INIT_LIST_HEAD(&proc->delivered_death);
	INIT_LIST_HEAD(&proc->waiting_threads);
	filp->private_data = proc;

	mutex_lock(&binder_procs_lock);
	hlist_add_head(&proc->proc_node, &binder_procs);
	mutex_unlock(&binder_procs_lock);

	if (binder_debugfs_dir_entry_proc) {
		char strbuf[11];

		snprintf(strbuf, sizeof(strbuf), "%u", proc->pid);
		/*
		 * proc debug entries are shared between contexts, so
		 * this will fail if the process tries to open the driver
		 * again with a different context. The priting code will
		 * anyway print all contexts that a given PID has, so this
		 * is not a problem.
		 */
		proc->debugfs_entry = debugfs_create_file(strbuf, 0444,
			binder_debugfs_dir_entry_proc,
			(void *)(unsigned long)proc->pid,
			&binder_proc_fops);
	}

	return 0;
}

创建binder_proc，放在filp->private_data = proc;插入链表
hlist_add_head(&proc->proc_node, &binder_procs);

其中，binder_proc 结构体：

struct binder_proc {
	struct hlist_node proc_node;　　//
	struct rb_root threads;   //红黑树，线程状态
	struct rb_root nodes;　　　//记录binder实体
	struct rb_root refs_by_desc;　//红黑树，用于快速查找，以handle为key
	struct rb_root refs_by_node; //红黑树，用于快速查找，以ptr为key
	struct list_head waiting_threads;
	int pid;
	struct task_struct *tsk;
	struct files_struct *files;
	struct mutex files_lock;
	struct hlist_node deferred_work_node;
	int deferred_work;
	bool is_dead;

	struct list_head todo;
	struct binder_stats stats;
	struct list_head delivered_death;
	int max_threads;
	int requested_threads;
	int requested_threads_started;
	int tmp_ref;
	struct binder_priority default_priority;
	struct dentry *debugfs_entry;
	struct binder_alloc alloc;
	struct binder_context *context;
	spinlock_t inner_lock;
	spinlock_t outer_lock;
};

本文地址：https://blog.csdn.net/zhangzhangru/article/details/107985665