On 12/14/19 11:13 AM, Markus Theil wrote: > 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. I've overlooked that ieee80211s_update_metric updates the rate avg.
