openwrt / openwrt/mt76

mt76x2u: multicast stops working in IBSS

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Dominant language
C
Stars
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Forks
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Description

Hello,
I'm putting "mt76x2u" in the title because this was where I saw the behaviour, not sure if happens in more places.
I'm using an Netgear A6210 (0846:9053) and setting it in IBSS mode and adding a default route for multicast traffic to the device.
Then I start sending multicast traffic with iperf (v2):

iperf -u -c 224.224.2.5 -b 37M -t 3500 -i 1
Confirm it is working by running monitor mode in another interface and checking the packets getting received.

After a few minutes later (sometimes in the first 20 seconds, sometimes almost a minute later) of continues multicast traffic the transmission stops on the iperf, only resuming if I send a ping to the same multicast address.

Other wireless interfaces don't have the issue (tested with an ath9k).

This was tested with kernel 5.4.0-52-generic, but also in an raspberry pi with kernel 5.9.1-v7+ the same test causes a crash in mt76x02_mac_work (dmesg attached).
dmesg_crash.log

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the IBSS multicast test with iperf and the mt76x2u device, then review the attached dmesg_crash.log and the mt76x02_mac_work path mentioned in the report. Done means multicast transmission continues without requiring a ping and the Raspberry Pi scenario no longer crashes.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, linux
Domain
networking, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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