Re: [Qemu-devel] [PATCH v2 8/9] netfilter: add a netbuffer filter

[Jason Wang <jasowang@redhat.com>]

On 07/31/2015 04:30 PM, Yang Hongyang wrote:
> On 07/31/2015 02:08 PM, Jason Wang wrote:
>>
>>
>> On 07/31/2015 12:13 PM, Yang Hongyang wrote:
>>> This filter is to buffer/release packets, this feature can be used
>>> when using MicroCheckpointing, or other Remus like VM FT solutions, you
>>> can also use it to simulate the network delay.
>>> It has an interval option, if supplied, this filter will release
>>> packets by interval.
>>>
>>> Usage:
>>>   -netdev tap,id=bn0
>>>   -netfilter buffer,id=f0,netdev=bn0,chain=in,interval=1000
>>>
>>> NOTE:
>>>   the scale of interval is microsecond.
>>>
>>> Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
>>> ---
>>>   net/Makefile.objs   |   1 +
>>>   net/filter-buffer.c | 160
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>   net/filter.c        |   2 +
>>>   net/filters.h       |  17 ++++++
>>>   qapi-schema.json    |  18 +++++-
>>>   5 files changed, 197 insertions(+), 1 deletion(-)
>>>   create mode 100644 net/filter-buffer.c
>>>   create mode 100644 net/filters.h
>>>
>>> diff --git a/net/Makefile.objs b/net/Makefile.objs
>>> index 914aec0..5fa2f97 100644
>>> --- a/net/Makefile.objs
>>> +++ b/net/Makefile.objs
>>> @@ -14,3 +14,4 @@ common-obj-$(CONFIG_SLIRP) += slirp.o
>>>   common-obj-$(CONFIG_VDE) += vde.o
>>>   common-obj-$(CONFIG_NETMAP) += netmap.o
>>>   common-obj-y += filter.o
>>> +common-obj-y += filter-buffer.o
>>> diff --git a/net/filter-buffer.c b/net/filter-buffer.c
>>> new file mode 100644
>>> index 0000000..7f2b050
>>> --- /dev/null
>>> +++ b/net/filter-buffer.c
>>> @@ -0,0 +1,160 @@
>>> +/*
>>> + * Copyright (c) 2015 FUJITSU LIMITED
>>> + * Author: Yang Hongyang <yanghy@cn.fujitsu.com>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>> + * later.  See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "net/filter.h"
>>> +#include "net/queue.h"
>>> +#include "filters.h"
>>> +#include "qemu-common.h"
>>> +#include "qemu/error-report.h"
>>> +#include "qemu/main-loop.h"
>>> +#include "qemu/timer.h"
>>> +#include "qemu/iov.h"
>>> +
>>> +typedef struct FILTERBUFFERState {
>>> +    NetFilterState nf;
>>> +    NetQueue *incoming_queue;
>>> +    NetQueue *inflight_queue;
>>> +    QEMUBH *flush_bh;
>>> +    int64_t interval;
>>> +    QEMUTimer release_timer;
>>> +} FILTERBUFFERState;
>>> +
>>> +static void packet_send_completed(NetClientState *nc, ssize_t len)
>>> +{
>>> +    return;
>>> +}
>>> +
>>> +static void filter_buffer_flush(NetFilterState *nf)
>>> +{
>>> +    FILTERBUFFERState *s = DO_UPCAST(FILTERBUFFERState, nf, nf);
>>> +    NetQueue *queue = s->inflight_queue;
>>> +    NetPacket *packet;
>>> +
>>> +    while (queue && !QTAILQ_EMPTY(&queue->packets)) {
>>> +        packet = QTAILQ_FIRST(&queue->packets);
>>> +        QTAILQ_REMOVE(&queue->packets, packet, entry);
>>> +        queue->nq_count--;
>>> +
>>> +        qemu_net_queue_send(packet->sender->peer->incoming_queue,
>>> +                            packet->sender,
>>> +                            packet->flags,
>>> +                            packet->data,
>>> +                            packet->size,
>>> +                            packet->sent_cb);
>>
>> Need to check peer since it may be NULL e.g after it was deleted. And we
>> probably need to queue the packet into next filter.
>
> Yes, if the peer is NULL, we can just free the packet and continue.
> we might need to check the sender too, because the sender might be
> deleted
> too...
>
> I was thinking when we remove the netdev, we also remove/free the filters
> attached to it automatically, do you think it is reasonable? because
> if the
> netdev is removed, the filters which attached to it is useless.

Yes, please do this.