On 2019/8/22 14:07, Yang Yingliang wrote:
On 2019/8/22 10:13, Jason Wang wrote:
On 2019/8/20 上午10:28, Jason Wang wrote:
On 2019/8/20 上午9:25, David Miller wrote:
From: Yang Yingliang <yangyingli...@huawei.com>
Date: Mon, 19 Aug 2019 21:31:19 +0800
Call tun_attach() after register_netdevice() to make sure tfile->tun
is not published until the netdevice is registered. So the read/write
thread can not use the tun pointer that may freed by free_netdev().
(The tun and dev pointer are allocated by alloc_netdev_mqs(), they
can
be freed by netdev_freemem().)
register_netdevice() must always be the last operation in the order of
network device setup.
At the point register_netdevice() is called, the device is visible
globally
and therefore all of it's software state must be fully initialized and
ready for us.
You're going to have to find another solution to these problems.
The device is loosely coupled with sockets/queues. Each side is
allowed to be go away without caring the other side. So in this
case, there's a small window that network stack think the device has
one queue but actually not, the code can then safely drop them.
Maybe it's ok here with some comments?
Or if not, we can try to hold the device before tun_attach and drop
it after register_netdevice().
Hi Yang:
I think maybe we can try to hold refcnt instead of playing real num
queues here. Do you want to post a V4?
I think the refcnt can prevent freeing the memory in this case.
When register_netdevice() failed, free_netdev() will be called directly,
dev->pcpu_refcnt and dev are freed without checking refcnt of dev.
How about using patch-v1 that using a flag to check whether the device
registered successfully.
Thanks
Thanks
.
.
