On Mon, 2017-11-20 at 17:34 +0100, Peter Große wrote: > Hi everyone. > > The iw tool allows to set TX power settings on network interfaces. > > If I try to set the TX power level on a _monitor_ interface, I get > a kernel warning: > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 2193 at net/mac80211/driver-ops.h:167 > ieee80211_bss_info_change_notify+0x111/0x190 Modules linked in: uvcvideo > videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_core > rndis_host cdc_ether usbnet mii tp_smapi(O) thinkpad_ec(O) ohci_hcd vboxpci(O) > vboxnetadp(O) vboxnetflt(O) v boxdrv(O) x86_pkg_temp_thermal kvm_intel kvm > irqbypass iwldvm iwlwifi ehci_pci ehci_hcd tpm_tis tpm_tis_core tpm CPU: 0 > PID: 2193 Comm: iw Tainted: G O 4.12.12-gentoo #2 task: > ffff880186fd5cc0 task.stack: ffffc90001b54000 RIP: > 0010:ieee80211_bss_info_change_notify+0x111/0x190 RSP: 0018:ffffc90001b57a10 > EFLAGS: 00010246 RAX: 0000000000000006 RBX: ffff8801052ce840 RCX: > 0000000000000064 RDX: 00000000fffffffc RSI: 0000000000040000 RDI: > ffff8801052ce840 RBP: ffffc90001b57a38 R08: 0000000000000062 R09: > 0000000000000000 R10: ffff8802144b5000 R11: ffff880049dc4614 R12: > 0000000000040000 R13: 0000000000000064 R14: ffff8802105f0760 R15: > ffffc90001b57b48 FS: 00007f92644b4580(0000) GS:ffff88021e200000(0000) > knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f9263c109f0 CR3: 00000001df850000 CR4: 00000000000406f0 > Call Trace: > ieee80211_recalc_txpower+0x33/0x40 > ieee80211_set_tx_power+0x40/0x180 > nl80211_set_wiphy+0x32e/0x950 > > Steps to reproduce: > > iw dev wlan0 interface add mon0 type monitor > ip link set dev mon0 up > iw dev mon0 set txpower fixed 100 > > Is that a bug to be fixed? Yeah, it's a bug. > What would be the correct way of fixing it? Maybe I can provide a patch. That's a really good question :-) I think if the driver has WANT_MONITOR_VIF, then we can pass that through and let the driver sort it out. But if not, we probably just have to reject the configuration? johannes
