On 08/06/2015 04:19 PM, Yang Hongyang wrote:
>
>
> On 08/06/2015 03:21 PM, Jason Wang wrote:
>>
>>
>> On 08/04/2015 04:30 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 <yan...@cn.fujitsu.com>
>>> ---
>>> v4: remove bh
>>> pass the packet to next filter instead of receiver
>>> v3: check packet's sender and sender->peer when flush it
>>> ---
>>> net/Makefile.objs | 1 +
>>> net/filter-buffer.c | 120
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> net/filter.c | 2 +
>>> net/filters.h | 17 ++++++++
>>> qapi-schema.json | 18 +++++++-
>>> 5 files changed, 157 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..fd467db
>>> --- /dev/null
>>> +++ b/net/filter-buffer.c
>>> @@ -0,0 +1,120 @@
>>> +/*
>>> + * Copyright (c) 2015 FUJITSU LIMITED
>>> + * Author: Yang Hongyang <yan...@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/timer.h"
>>> +#include "qemu/iov.h"
>>> +
>>> +typedef struct FILTERBUFFERState {
>>> + NetFilterState nf;
>>> + NetQueue *incoming_queue;
>>> + int64_t interval;
>>
>> Can interval be negative?
>
> No.
>
>> If not please uint. And not sure you really
>> need a 64 bit integer, if not, please use uint32_t.
>
> Ok, will use uint32_t instead.
>
>>
>>> + QEMUTimer release_timer;
>>> +} FILTERBUFFERState;
>>
>> Filter buffer is not abbreviation. So better name it as
>> FilterBufferState.
>
> Ok, thanks.
>
>>
>>> +
>>> +static void packet_send_completed(NetClientState *nc, ssize_t len)
>>> +{
>>> + return;
>>> +}
>>
>> Why need a dummy sent cb?
>
> Need to work around with queue_append, if there's no sent_cb,
> queue_append
> will simply drop the packet...Even we provide a sent_cb param to
> receive_iov,
> this dummy might still be needed because sent_cb might be null.
Dropping happens only when the number of queued packet exceeds queue
limitation and no sent_cb. Isn't this just what we want? And like we've
discussed, we need track packet->sent_cb so it was not a problem?
>
>>
>>> +
>>> +static void filter_buffer_flush(NetFilterState *nf)
>>> +{
>>> + FILTERBUFFERState *s = DO_UPCAST(FILTERBUFFERState, nf, nf);
>>> + NetQueue *queue = s->incoming_queue;
>>> + NetPacket *packet;
>>> +
>>> + while (queue && !QTAILQ_EMPTY(&queue->packets)) {
>>> + packet = QTAILQ_FIRST(&queue->packets);
>>> + QTAILQ_REMOVE(&queue->packets, packet, entry);
>>> + queue->nq_count--;
>>> +
>>> + if (packet->sender && packet->sender->peer) {
>>> + qemu_netfilter_pass_to_next(nf, packet->sender,
>>> packet->flags,
>>> + packet->data, packet->size);
>>> + }
>>> +
>>> + /*
>>> + * now that we pass the packet to next filter, we don't
>>> care the
>>> + * reture value here, because the filter layer or other filter
>>> + * will take care of this packet
>>> + */
>>> + g_free(packet);
>>
>> This seems wrong, since packet could be queued into incoming queue.
>> Doing this may cause use after free.
>
> The incoming queue will make a copy of packet data when queued a packet.
> So I think it's ok to free this packet here...because this packet is
> alloced by this filter when calling qemu_net_queue_append_iov.
>
You're right. I see.
>>
>>> + }
>>> +}
>>> +
>>> +static void filter_buffer_release_timer(void *opaque)
>>> +{
>>> + FILTERBUFFERState *s = opaque;
>>> + filter_buffer_flush(&s->nf);
>>> + timer_mod(&s->release_timer,
>>> + qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) + s->interval);
>>> +}
>>> +
>>> +/* filter APIs */
>>> +static ssize_t filter_buffer_receive_iov(NetFilterState *nf,
>>> + NetClientState *sender,
>>> + unsigned flags,
>>> + const struct iovec *iov,
>>> + int iovcnt)
>>> +{
>>> + FILTERBUFFERState *s = DO_UPCAST(FILTERBUFFERState, nf, nf);
>>> + NetQueue *queue = s->incoming_queue;
>>> +
>>> + qemu_net_queue_append_iov(queue, sender, flags, iov, iovcnt,
>>> + packet_send_completed);
>>> + return iov_size(iov, iovcnt);
>>
>> So if interval is zero, packet will be blocked forever and memory will
>> be exhausted.
>
> Yes, but this supposed to be used by FT solutions, so it will
> be released periodically. Currently only used with interval makes sense.
>
Then you need terminate the initialization when interval is zero.
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