Re: [PATCH 1/2] net: forbid the reentrant RX

[Jason Wang <jasowang@redhat.com>]

On 2020/9/2 下午11:56, Alexander Bulekov wrote:
> On 200728 1200, Jason Wang wrote:
>> On 2020/7/22 下午4:57, Jason Wang wrote:
>>> The memory API allows DMA into NIC's MMIO area. This means the NIC's
>>> RX routine must be reentrant. Instead of auditing all the NIC, we can
>>> simply detect the reentrancy and return early. The queue->delivering
>>> is set and cleared by qemu_net_queue_deliver() for other queue helpers
>>> to know whether the delivering in on going (NIC's receive is being
>>> called). We can check it and return early in qemu_net_queue_flush() to
>>> forbid reentrant RX.
>>>
>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>> ---
>>>    net/queue.c | 3 +++
>>>    1 file changed, 3 insertions(+)
>>>
>>> diff --git a/net/queue.c b/net/queue.c
>>> index 0164727e39..19e32c80fd 100644
>>> --- a/net/queue.c
>>> +++ b/net/queue.c
>>> @@ -250,6 +250,9 @@ void qemu_net_queue_purge(NetQueue *queue, NetClientState *from)
>>>    bool qemu_net_queue_flush(NetQueue *queue)
>>>    {
>>> +    if (queue->delivering)
>>> +        return false;
>>> +
>>>        while (!QTAILQ_EMPTY(&queue->packets)) {
>>>            NetPacket *packet;
>>>            int ret;
>>
>> Queued for rc2.
>>
>> Thanks
>>
> Hi Jason,
> I don't think this ever made it in. Are there any remaining problems?
> Thanks
> -Alex


Hi Alex:

It should have been merged:

https://git.qemu.org/?p=qemu.git;a=commit;h=22dc8663d9fc7baa22100544c600b6285a63c7a3

Thanks


>