Aleksander Morgado <aleksande...@chromium.org> writes: > Hey Bjørn, > > I'm getting some strange reports of failures in the netlink > communication when adding new multiplexed links in a MBIM modem, using > cdc_mbim. I also have the kernel dmesg but it doesn't give any > reference to the error, the only valid thing I have is the MM debug > log. > > Any idea why this may fail? If I'm not mistaken, the actual > multiplexed net interface creation is a process done by the kernel > alone, without any interaction with the device, so not sure what could > be happening. > > 2024-01-15T06:52:20.192634Z NOTICE ModemManager[4658]: <msg> [modem6] > state changed (registered -> connecting) > 2024-01-15T06:52:20.192901Z DEBUG ModemManager[4658]: <dbg> > [modem6/bearer2] launching multiplexed connection with data port > (net/wwan0) > 2024-01-15T06:52:20.192912Z DEBUG ModemManager[4658]: <dbg> > [modem6/bearer2] setting up new multiplexed link... > 2024-01-15T06:52:20.193219Z DEBUG ModemManager[4658]: <dbg> Using > dynamic session ID 1 > 2024-01-15T06:52:20.193259Z DEBUG ModemManager[4658]: <dbg> Using > ifname 'mbimmux6.1' and vlan id 1 > 2024-01-15T06:52:20.193506Z WARNING ModemManager[4658]: <wrn> > [modem6/bearer2] connection attempt #1 failed: failed to create net > link for device: failed to add link for device: Could not allocate > link: Failed to add link with session id 1: Netlink message with > transaction 1 failed: Unknown error -1 > 2024-01-15T06:52:20.193634Z DEBUG ModemManager[4658]: <dbg> > [modem6/bearer2] cannot set unhandled domain error as connection > error: failed to create net link for device: failed to add link for > device: Could not allocate link: Failed to add link with session id 1: > Netlink message with transaction 1 failed: Unknown error -1 > 2024-01-15T06:52:20.193684Z NOTICE ModemManager[4658]: <msg> [modem6] > state changed (connecting -> registered) > 2024-01-15T06:52:20.193973Z NOTICE ModemManager[4658]: <msg> > [modem6/bearer2] connection #1 finished: duration 0s > 2024-01-15T06:52:20.193996Z WARNING ModemManager[4658]: <wrn> [modem6] > couldn't connect bearer: failed to create net link for device: failed > to add link for device: Could not allocate link: Failed to add link > with session id 1: Netlink message with transaction 1 failed: Unknown > error -1
Afraid I cant help much with this. I'm really no expert in this area. Looks like vlan_newlink() can fail in a number of ways: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/8021q/vlan_netlink.c#n140 And several of those return paths are silent, making it hard to guess why it failed. I guess that -1 is the result of some translation and not the real errno? If you can reproduce this somewhat reliably then you could try adding extra debugging to all the error paths. Otherwise I really don't know how to figure out exactly where this fails. Not much help there... Bjørn
