Kernel panic with 64bit Snow Leopard and sendAsyncNotification

25 Dec 2008

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Thread-index: AclmznNcsBPNqTjSTaSfJPWbJNhn9w==
Thread-topic: Kernel panic with 64bit Snow Leopard and sendAsyncNotification

I'm trying to bring to work the kextension + application(32bit, compiled on SDK10.4) on 64 bit Snow Leopard and have permanent Kernel Panic when my kextension does sendAsyncNotification to application. The panic (it seems so) occurs in ipc_object_copyin_from_kernel -> ip_lock(port) -> mutex_lock(...)

The code looks usual (in the end of the mail).. Anyway, my thoughts that user mode application should not be able to send the kernel to panic, so the mach_port should be checked somewhere in kernel, so it seems to be a problem somewhere in 10.6, doesn't it? Or may be it is I that missing something..

I know, that recent sources do the callbacks using the IOConnectCallAsyncMethod, but I don't see the reason why this code causes panics.

Could someone please point me to directions to look for? (32-bit 10.6 works ok)

Thanks in advance!

---
Dmitry Skorodumov

PS: Below goes the application and extension

---

Application:

io_connect_t conn; // initialized somewhere
IONotificationPortRef nport; // nport = IONotificationPortCreate(kIOMasterPortDefault)
typedef void (*notify_func)(void *ref, IOReturn r);

int
init()
{
	notify_func func; // initialized to point to my callback
	// ...
	mach_port_t port = IONotificationPortGetMachPort(nport)

	if ( IOConnectSetNotificationPort(conn, 0/*type*/, port, some_ctx) != KERN_SUCCESS)
		return -1;

	if ( IOConnectMethodScalarIScalarO(conn, kMethodSetCallback, 1, 0, func) != KERN_SUCCESS )
		return -1;

	return 0;
}

---

Extension:

static struct notification_s {
	mach_port_t port;
	unsigned conn;
	notify_func callback;
	OSAsyncReference async;
} notify; // is zeroed somewhere

IOReturn
Xxx_UserClient::registerNotificationPort(
	mach_port_t port, UInt32 type, UInt32 conn)
{
         notify.port = port;
         notify.conn = conn;
}

IOReturn
XXX_PrlnetUserClient::iomsetcb(
	notify_func callback)
{
	if (!this->notify.port || !callback)
		return kIOReturnError;

	setAsyncReference(
		notify.async, notify.port,
		(void *)callback, (void *) notify.conn);
}

And to fire the callback,

XXX_PrlnetUserClient::Xxx_Fire()
{
	if (!notify.port )
		return;

	this->sendAsyncResult( notify.async, kIOReturnSuccess, NULL/*args*/, 0/*nargs*/);
}

---
The end
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