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net: fix qemu_can_send_packet logic 

If any of the clients is not ready to receive (ie it has a can_receive
callback and can_receive() returns false), we don't want to start
sending, else this client may miss/discard the packet.

I got this behaviour with the following setup :
the emulated machine is using an USB-ethernet adapter, it is connected
to the network using SLIRP and I'm dumping the traffic in a .pcap file.
As per the following command line :
-net nic,model=usb,vlan=1 -net user,vlan=1 -net dump,vlan=1,file=/tmp/pkt.pcap
Every time that two packets are coming in a row from the host, the
usb-net code will receive the first one, then returns 0 to can_receive
call since it has a 1 packet long queue. But as the dump code is always
ready to receive, qemu_can_send_packet will return true and the next
packet will discard the previous one in the usb-net code.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Vincent Palatin 2011-03-02 17:25:02 -05:00 committed by Blue Swirl
parent 24ac3a7d4e
commit 60c07d933c
1 changed files with 3 additions and 3 deletions
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6
net.c
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@ -411,11 +411,11 @@ int qemu_can_send_packet(VLANClientState *sender)
}
/* no can_receive() handler, they can always receive */
if (!vc->info->can_receive || vc->info->can_receive(vc)) {
return 1;
if (vc->info->can_receive && !vc->info->can_receive(vc)) {
return 0;
}
}
return 0;
return 1;
}
static ssize_t qemu_deliver_packet(VLANClientState *sender,