v3.8.5: "TCP: snd_cwnd is nul, please report this bug."

["Bjørn Mork" <bjorn@mork.no>]

Hello,

I just got this message running a Debian experimental
linux-image-3.8-trunk-amd64 kernel, currently based on v3.8.5.

Peeked briefly through the commit adding the message, but I couldn't
figure out what other info you'd need so please ask if there is anything
I can dig up.

I suspect the warning could be related to problems with the iwlwifi
driver and/or access point.  The message was immediately followed  by a
few messges from iwlwifi:


Apr  8 10:58:09 nemi kernel: [152701.980799] TCP: snd_cwnd is nul, please report this bug.
Apr  8 10:58:33 nemi kernel: [152725.176151] iwlwifi 0000:03:00.0: fail to flush all tx fifo queues
Apr  8 10:58:33 nemi kernel: [152725.185713] wlan0: authenticate with 00:22:90:f9:23:a0
Apr  8 10:58:33 nemi kernel: [152725.185738] wlan0: capabilities/regulatory prevented using AP HT/VHT configuration, downgraded
Apr  8 10:58:33 nemi kernel: [152725.190150] wlan0: send auth to 00:22:90:f9:23:a0 (try 1/3)
Apr  8 10:58:33 nemi kernel: [152725.199812] wlan0: authenticated
Apr  8 10:58:33 nemi kernel: [152725.200020] iwlwifi 0000:03:00.0 wlan0: disabling HT as WMM/QoS is not supported by the AP
Apr  8 10:58:33 nemi kernel: [152725.200027] iwlwifi 0000:03:00.0 wlan0: disabling VHT as WMM/QoS is not supported by the AP
Apr  8 10:58:33 nemi kernel: [152725.204033] wlan0: associate with 00:22:90:f9:23:a0 (try 1/3)
Apr  8 10:58:33 nemi kernel: [152725.207317] wlan0: RX AssocResp from 00:22:90:f9:23:a0 (capab=0x421 status=0 aid=12)
Apr  8 10:58:33 nemi kernel: [152725.210745] wlan0: associated



Bjørn