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Re: [Qemu-stable] [PATCH] net: fix qemu_announce_self not emitting packe
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-stable] [PATCH] net: fix qemu_announce_self not emitting packets |
Date: |
Tue, 7 Jun 2016 10:23:09 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 |
On 07/06/2016 10:02, Peter Lieven wrote:
> Am 07.06.2016 um 09:55 schrieb Paolo Bonzini:
>>
>> On 07/06/2016 09:37, Peter Lieven wrote:
>>> commit fefe2a78 accidently dropped the code path for injecting
>>> raw packets. This feature is needed for sending gratuitous ARPs
>>> after an incoming migration has completed. The result is increased
>>> network downtime for vservers where the network card is not virtio-net
>>> with the VIRTIO_NET_F_GUEST_ANNOUNCE feature.
>>>
>>> Fixes: fefe2a78abde932e0f340b21bded2c86def1d242
>>> Cc: address@hidden
>>> Cc: address@hidden
>>> Signed-off-by: Peter Lieven <address@hidden>
>>> ---
>>> net/net.c | 6 +++++-
>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/net/net.c b/net/net.c
>>> index 5f3e5a9..d5834ea 100644
>>> --- a/net/net.c
>>> +++ b/net/net.c
>>> @@ -722,7 +722,11 @@ ssize_t qemu_deliver_packet_iov(NetClientState
>>> *sender,
>>> return 0;
>>> }
>>> - if (nc->info->receive_iov) {
>>> + if (flags & QEMU_NET_PACKET_FLAG_RAW && iovcnt == 1 &&
>>> + nc->info->receive_raw) {
>>> + /* this is required for qemu_announce_self() */
>>> + ret = nc->info->receive_raw(nc, iov[0].iov_base,
>>> iov[0].iov_len);
>> Possibly move "iovcnt == 1" from the if condition to an assertion
>> inside it?
>
> I do not know if there is any other user that emits raw packets than
> qemu_announce_self.
Currently all senders of raw packets go through qemu_send_packet_raw,
which has iovcnt == 1.
> The question is do you want to abort or just return -1 (which is the
> case without this patch).
I want to abort, since it's currently impossible to get into that
situation. If someone wants to introduce
qemu_sendv_packet_async_with_flags, they must also introduce
nc->info->receive_raw_iov or something like that.
Thanks,
Paolo