linux-kernel - Re: [PATCH 0/4] Fix probe failed when modprobe modules

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Date:   Mon, 19 Dec 2022 05:15:09 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     Li Zetao <lizetao1@...wei.com>, pbonzini@...hat.com,
        stefanha@...hat.com, axboe@...nel.dk, kraxel@...hat.com,
        david@...hat.com, ericvh@...il.com, lucho@...kov.net,
        asmadeus@...ewreck.org, linux_oss@...debyte.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, rusty@...tcorp.com.au,
        virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        v9fs-developer@...ts.sourceforge.net, netdev@...r.kernel.org
Subject: Re: [PATCH 0/4] Fix probe failed when modprobe modules

On Tue, Nov 29, 2022 at 11:37:09AM +0800, Jason Wang wrote:
> >
> >
> > Quite a lot of core work here. Jason are you still looking into
> > hardening?
> 
> Yes, last time we've discussed a solution that depends on the first
> kick to enable the interrupt handler. But after some thought, it seems
> risky since there's no guarantee that the device work in this way.
> 
> One example is the current vhost_net, it doesn't wait for the kick to
> process the rx packets. Any more thought on this?
> 
> Thanks

Specifically virtio net is careful to call virtio_device_ready
under rtnl lock so buffers are only added after DRIVER_OK.

However we do not need to tie this to kick, this is what I wrote:

> BTW Jason, I had the idea to disable callbacks until driver uses the
> virtio core for the first time (e.g. by calling virtqueue_add* family of
> APIs). Less aggressive than your ideas but I feel it will add security
> to the init path at least.

So not necessarily kick, we can make adding buffers allow the
interrupt.



-- 
MST