[FS#4122] Enabling WiFi hangs the whole system (both RPi4 and NanoPi R1)

OpenWrt Bugs openwrt-bugs at lists.openwrt.org
Thu Nov 4 09:13:15 PDT 2021


A new Flyspray task has been opened.  Details are below. 

User who did this - Piotr Jurkiewicz (piotrjurkiewicz) 

Attached to Project - OpenWrt/LEDE Project
Summary - Enabling WiFi hangs the whole system (both RPi4 and NanoPi R1)
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Critical
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Enabling WiFi with `wifi up` blocks all Netlink communication with kernel, effectively hanging the whole system.

After issuing `wifi up` command, netifd calls mac80211.sh script, which in turn call `iw phy phy0 set distance 0`.

812     1 root     S     1804   0%   0% /sbin/netifd
 1650   812 root     S     1972   0%   0% /bin/sh ./mac80211.sh mac80211 setup radio0 {"config":{"path":"platform/soc/fe300000.mmcnr/mmc_hos
  1676  1650 root     D     1068   0%   0% iw phy phy0 set distance 0

The `iw phy phy0 set distance 0` command gets stuck on disk (kernel) write, the wchan is:


Any event or command happening afterwards (like DHCP association or `ip link` command) also get stuck on Netlink read/write, effectively hanging the whole system:

1695  1679 root     D     1236   0%   0% ip link

I observe the problem on both my machines, RaspberryPi 4 and sunxi friendlyarm_nanopi-r1. The problem is independent from the kernel version used (5.4 or 5.10), because it also happens with sunxi target compiled with KERNEL_PATCHVER:=5.4. I already used 5.10 on RPi4 without the problem around 43f0e386d4e79e9014e926d1d9b5e2ff8f1379cb, so it was introduced after that commit.

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