On 12/13/19 10:13 AM, Johannes Berg wrote: > On Tue, 2019-12-03 at 19:06 +0100, Markus Theil wrote: >> The following warning is triggered every time an unestablished mesh peer >> gets dumped. This patch checks, if a peer link is established, when dum- >> ping the airtime link metric. >> >> [ 9563.022567] WARNING: CPU: 0 PID: 6287 at net/mac80211/mesh_hwmp.c:345 >> airtime_link_metric_get+0xa2/0xb0 [mac80211] >> [ 9563.022697] Hardware name: PC Engines apu2/apu2, BIOS v4.10.0.3 >> [ 9563.022756] RIP: 0010:airtime_link_metric_get+0xa2/0xb0 [mac80211] >> [ 9563.022838] Call Trace: >> [ 9563.022897] sta_set_sinfo+0x936/0xa10 [mac80211] >> [ 9563.022964] ieee80211_dump_station+0x6d/0x90 [mac80211] >> [ 9563.023062] nl80211_dump_station+0x154/0x2a0 [cfg80211] >> [ 9563.023120] netlink_dump+0x17b/0x370 >> [ 9563.023130] netlink_recvmsg+0x2a4/0x480 >> [ 9563.023140] ____sys_recvmsg+0xa6/0x160 >> [ 9563.023154] ___sys_recvmsg+0x93/0xe0 >> [ 9563.023169] __sys_recvmsg+0x7e/0xd0 >> [ 9563.023210] do_syscall_64+0x4e/0x140 >> [ 9563.023217] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > OK, I can see how this happens. > > However, > >> + if (sta->mesh->plink_state != NL80211_PLINK_ESTAB) >> + return MAX_METRIC; >> + > I'm not really sure this is the right way to fix it? > > I'm sure you observed this only when the link isn't established yet, but > it seems to me that even when a link is established it could still > happen? > > Or are the frames that are necessary for link establishment enough to > always set the metric? > > johannes The current mac80211 code initializes this moving average when setting the peer link to established in sta_apply_mesh_params. case NL80211_PLINK_ESTAB: ... ewma_mesh_tx_rate_avg_init(&sta->mesh->tx_rate_avg); /* init at low value */ ewma_mesh_tx_rate_avg_add(&sta->mesh->tx_rate_avg, 10); break; This ewma_mesh_tx_rate_avg_add is the only reference that I found in the code. It seems, that this avg is only initialized and never updated during the plink lifetime. -- Markus Theil Technische Universität Ilmenau, Fachgebiet Telematik/Rechnernetze Postfach 100565 98684 Ilmenau, Germany Phone: +49 3677 69-4582 Email: markus[dot]theil[at]tu-ilmenau[dot]de Web: http://www.tu-ilmenau.de/telematik
