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Date: Wed, 2 Sep 2015 09:49:18 +0800
From: Yang Hongyang <yanghy@cn.fujitsu.com>
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Subject: Re: [Qemu-devel] [PATCH v9 05/10] move out net queue structs define
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: thuth@redhat.com, zhang.zhanghailiang@huawei.com, lizhijian@cn.fujitsu.com, jasowang@redhat.com, qemu-devel@nongnu.org, mrhines@linux.vnet.ibm.com, armbru@redhat.com

On 09/01/2015 10:43 PM, Stefan Hajnoczi wrote:
> On Tue, Sep 01, 2015 at 05:06:18PM +0800, Yang Hongyang wrote:
>> This will be used by the next patch in this series.
>>
>> Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
>> Reviewed-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   include/net/queue.h | 19 +++++++++++++++++++
>>   net/queue.c         | 19 -------------------
>>   2 files changed, 19 insertions(+), 19 deletions(-)
>>
>> diff --git a/include/net/queue.h b/include/net/queue.h
>> index fc02b33..1d65e47 100644
>> --- a/include/net/queue.h
>> +++ b/include/net/queue.h
>> @@ -31,6 +31,25 @@ typedef struct NetQueue NetQueue;
>>
>>   typedef void (NetPacketSent) (NetClientState *sender, ssize_t ret);
>>
>> +struct NetPacket {
>> +    QTAILQ_ENTRY(NetPacket) entry;
>> +    NetClientState *sender;
>> +    unsigned flags;
>> +    int size;
>> +    NetPacketSent *sent_cb;
>> +    uint8_t data[0];
>> +};
>> +
>> +struct NetQueue {
>> +    void *opaque;
>> +    uint32_t nq_maxlen;
>> +    uint32_t nq_count;
>> +
>> +    QTAILQ_HEAD(packets, NetPacket) packets;
>> +
>> +    unsigned delivering:1;
>> +};
>> +
>
> Why is it necessary to expose both structs?

In next patch, we add a API to pass the packet to next filter:
ssize_t qemu_netfilter_pass_to_next(NetFilterState *nf, NetPacket *packet);
which will access the internals of NetPacket.

and in buffer filter, we need the NetQueue to Queue packets, and also to
access queue->packets(pass this packets to next filter).

>
> Normally functions would be added to maintain the abstraction.  Instead,
> you have chosen to access the fields directly - this is probably a bad
> idea.
> .
>

-- 
Thanks,
Yang.