linux-kernel - Re: [PATCH 0/4] vsock/virtio: several fixes in the .probe() and .remove()

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Message-ID: <20190610130945.GL14257@stefanha-x1.localdomain>
Date:   Mon, 10 Jun 2019 14:09:45 +0100
From:   Stefan Hajnoczi <stefanha@...il.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     netdev@...r.kernel.org, kvm@...r.kernel.org,
        "Michael S . Tsirkin" <mst@...hat.com>,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH 0/4] vsock/virtio: several fixes in the .probe() and
 .remove()

On Tue, May 28, 2019 at 12:56:19PM +0200, Stefano Garzarella wrote:
> During the review of "[PATCH] vsock/virtio: Initialize core virtio vsock
> before registering the driver", Stefan pointed out some possible issues
> in the .probe() and .remove() callbacks of the virtio-vsock driver.
> 
> This series tries to solve these issues:
> - Patch 1 postpones the 'the_virtio_vsock' assignment at the end of the
>   .probe() to avoid that some sockets queue works when the initialization
>   is not finished.
> - Patches 2 and 3 stop workers before to call vdev->config->reset(vdev) to
>   be sure that no one is accessing the device, and adds another flush at the
>   end of the .remove() to avoid use after free.
> - Patch 4 free also used buffers in the virtqueues during the .remove().
> 
> Stefano Garzarella (4):
>   vsock/virtio: fix locking around 'the_virtio_vsock'
>   vsock/virtio: stop workers during the .remove()
>   vsock/virtio: fix flush of works during the .remove()
>   vsock/virtio: free used buffers during the .remove()
> 
>  net/vmw_vsock/virtio_transport.c | 105 ++++++++++++++++++++++++++-----
>  1 file changed, 90 insertions(+), 15 deletions(-)

Looking forward to v2.  I took a look at the discussion and I'll review
v2 from scratch.  Just keep in mind that the mutex is used more for
mutual exclusion of the init/exit code than to protect the_virtio_vsock,
so we'll still need protection of init/exit code even with RCU.

Stefan

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