netdev - Re: [PATCH 3/4] vsock: add pkt cancel capability

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Message-ID: <CA+a=Yy7cwuSG57bpzdV7zJBAbSH009OFaH9MP_+8-wkY53uVgg@mail.gmail.com>
Date:   Wed, 7 Dec 2016 22:46:40 +0800
From:   Peng Tao <bergwolf@...il.com>
To:     Stefan Hajnoczi <stefanha@...il.com>
Cc:     Stefan Hajnoczi <stefanha@...hat.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 3/4] vsock: add pkt cancel capability

On Wed, Dec 7, 2016 at 9:22 PM, Stefan Hajnoczi <stefanha@...il.com> wrote:
> On Wed, Dec 07, 2016 at 06:00:20PM +0800, Peng Tao wrote:
>> Signed-off-by: Peng Tao <bergwolf@...il.com>
>> ---
>>  net/vmw_vsock/virtio_transport.c | 36 ++++++++++++++++++++++++++++++++++++
>>  1 file changed, 36 insertions(+)
>>
>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>> index 936d7ee..f88b6ed 100644
>> --- a/net/vmw_vsock/virtio_transport.c
>> +++ b/net/vmw_vsock/virtio_transport.c
>> @@ -170,6 +170,41 @@ virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt)
>>       return len;
>>  }
>>
>> +static int
>> +virtio_transport_cancel_pkt(struct vsock_sock *vsk)
>> +{
>> +     struct virtio_vsock *vsock;
>> +     struct virtio_vsock_pkt *pkt, *n;
>> +     int cnt = 0;
>> +     LIST_HEAD(freeme);
>> +
>> +     vsock = virtio_vsock_get();
>> +     if (!vsock) {
>> +             return -ENODEV;
>> +     }
>> +
>> +     if (pkt->reply)
>
> pkt is uninitialized.  I guess this if statement should be deleted, you
> already take care of counting reply packets below.
>
ah, sorry! I forgot to delete it after handling cnt below...

>> +             cnt++;
>> +
>> +     spin_lock_bh(&vsock->send_pkt_list_lock);
>> +     list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
>> +             if (pkt->vsk != vsk)
>> +                     continue;
>> +             list_move(&pkt->list, &freeme);
>> +     }
>> +     spin_unlock_bh(&vsock->send_pkt_list_lock);
>> +
>> +     list_for_each_entry_safe(pkt, n, &freeme, list) {
>> +             if (pkt->reply)
>> +                     cnt++;
>> +             list_del(&pkt->list);
>> +             virtio_transport_free_pkt(pkt);
>> +     }
>> +     atomic_sub(cnt, &vsock->queued_replies);
>
> If we stopped rx because there were too many replies in flight then we
> might be able to resume rx now:
>
> /* Do we now have resources to resume rx processing? */
> if (old_val >= virtqueue_get_vring_size(rx_vq) &&
>     new_val < virtqueue_get_vring_size(rx_vq))
>         queue_work(virtio_vsock_workqueue, &vsock->rx_work);
Thanks! I totally missed the resume part... I'll send an updated version later.

Cheers,
Tao