netdev - Re: [PATCH-v4-RESEND 1/4] vsock: track pkt owner vsock

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Date:   Fri, 3 Mar 2017 09:25:54 +0800
From:   Peng Tao <bergwolf@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Jorgen Hansen <jhansen@...are.com>
Subject: Re: [PATCH-v4-RESEND 1/4] vsock: track pkt owner vsock

On Fri, Mar 3, 2017 at 5:13 AM, David Miller <davem@...emloft.net> wrote:
> From: Peng Tao <bergwolf@...il.com>
> Date: Wed,  1 Mar 2017 11:56:24 +0800
>
>> So that we can cancel a queued pkt later if necessary.
>>
>> Reviewed-by: Stefan Hajnoczi <stefanha@...hat.com>
>> Signed-off-by: Peng Tao <bergwolf@...il.com>
>> ---
>>  include/linux/virtio_vsock.h            | 2 ++
>>  net/vmw_vsock/virtio_transport_common.c | 7 +++++++
>>  2 files changed, 9 insertions(+)
>>
>> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>> index 9638bfe..193ad3a 100644
>> --- a/include/linux/virtio_vsock.h
>> +++ b/include/linux/virtio_vsock.h
>> @@ -48,6 +48,7 @@ struct virtio_vsock_pkt {
>>       struct virtio_vsock_hdr hdr;
>>       struct work_struct work;
>>       struct list_head list;
>> +     void *cancel_token; /* only used for cancellation */
>
> The type here is fixed, you only store vhost_sock object pointers
> here, so don't use "void *" please.
It used to be "struct vhost_sock *" but no refcount is held. Stefan
suggested to use "void *cancel_token" to make the code harder to
misuse.

Quoting Stefan:
"This field is just an opaque token used for cancellation rather than
a struct vsock_sock pointer that we are allowed to dereference.  You
could change this field to void *cancel_token to make the code harder
to misuse."

Ref:
https://www.mail-archive.com/netdev@vger.kernel.org/msg142550.html

Cheers,
Tao