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

[Alexander Bulekov]

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