通用内核扩展无法释放OsObject派生类

Generic kernel Extension Cannot release OSObject derived class

本文关键字：释放 OsObject 派生 内核 扩展      更新时间：2023-10-16

我有一个通用内核扩展名，该扩展是在开始和结束例程的C 示例中实现的，而所有其他逻辑都存储在从OSObject继承的专用类中。

它在模块启动例程上创建类，并在停止例程中释放它，如下所示：

： 
class com_my_driver : public OSObject { ... };
...
..
.
com_my_driver *gDriver = NULL;
extern "C" kern_return_t my_driver_start(kmod_info_t * ki, void *d)
{
    gDriver = new com_my_driver;
    gDriver->init();
    return KERN_SUCCESS;
}
extern "C" kern_return_t my_driver_stop(kmod_info_t *ki, void *d)
{
    gDriver->release();
    gDriver = nullptr;
    return KERN_SUCCESS;
}

但是，在尝试卸载服务时，由于仍在引用该类，因此无法达到停止例程（我认为它可以到达我发布此类的停止例程）。这是确切的日志消息：

(kernel) Can't unload kext com.my.driver; classes have instances:
(kernel)     Kext com.my.driver class com_my_driver has 1 instance.
Failed to unload com.my.driver - (libkern/kext) kext is in use or retained (cannot unload).

即使在参考检查之前我可以在停止例程之前释放我的班级？

谢谢

我最近遇到了同样的问题，然后我放弃了（在kext停止功能中发布我的课程）。
我认为，OsObject及其派生类并不适合这种用例。

必须在另一个地方完成创建和删除（释放）：

// do new in connect(), release in disconnect().
#include <sys/kern_control.h>
...
static kern_ctl_ref g_ctl_ref;
static kern_ctl_reg g_ctl;
...
static errno_t setup() {
    g_ctl.ctl_id = 0;
    g_ctl.ctl_flags = CTL_FLAG_REG_ID_UNIT /*| CTL_FLAG_REG_SOCK_STREAM */;
    g_ctl.ctl_connect = connect_handler;
    g_ctl.ctl_send = send_handler;
    g_ctl.ctl_disconnect = disconnect_handler;
    g_ctl.ctl_getopt = getopt_handler;
    g_ctl.ctl_setopt = setopt_handler;
    strcpy(g_ctl.ctl_name, "kext_control_name");
    g_ctl.ctl_unit = 0;
    return ctl_register(&g_ctl, &g_ctl_ref);
}
static errno_t connect_handler(kern_ctl_ref ctlref, struct sockaddr_ctl *sac, void **unitinfo)
{
    gDriver = new com_my_driver;
    gDriver->init();
    // just my pattern, if your driver class has connect method..
    return gDriver->connect(ctlref, sac, unitinfo);
}
static errno_t disconnect_handler(kern_ctl_ref ctlref, unsigned int unit, void *unitinfo)
{
    // just my patter, if your class has disconnect method.
    gDriver->disconnect(ctlref, unit, unitinfo);
    gDriver->release();
    return 0;
}
...
// other handlers...
extern "C" kern_return_t com_my_driver_start(kmod_info_t * ki, void *d)
{
    setup();
}
//

内核控件的官方描述是：https://developer.apple.com/library/archive/documentation/darwin/conceptual/nkeconpeptual/control/control/control.html

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