Systemd Suspend Hook to Fix WiFi Arch Linux

Jun 28, 2017

archlinux, linux, hacks, systemd

My macbook running Arch Linux is currently having problems with the WiFi after resume from suspend.

Systemd provides a mechanism to run executable files before and after suspend or hibernation. /usr/lib/systemd/system-sleep

This mechanism relies on the system service systemd-suspend.service, this service will run all executable files in /usr/lib/systemd/system-sleep/.

Two arguments are going to be passed to the script, before suspend the execution will look to something like:

/usr/lib/systemd/system-sleep/wifi-hook.sh "pre" "suspend"

After suspend, the execution will be:

/usr/lib/systemd/system-sleep/wifi-hook.sh "post" "suspend"

Is up to you the implementation details, I just wrote a quick hackish bash script:

  #!/bin/sh

  _log () {
      echo "[$0] $1" | systemd-cat
  }

  _stop_wifi () {
    if nmcli networking off; then
        _log "Network stoped via nmcli"
    else
        _log "Error stopping network via nmcli"
    fi

    if modprobe -r wl; then
        _log "Kernel module [wl] removed"
    else
        _log "Error removing kernel module [wl]"
    fi
  }

  _start_wifi () {
      if modprobe wl; then
          _log "Kernel module [wl] loaded"
      else
          _log "Error loading Kernel module [wl]"
      fi

      if nmcli networking on; then
          _log "Network set to ON via nmcli"
      else
          _log "Error while setting Network to ON via nmcli"
      fi
  }

  _pre () {
      _stop_wifi
  }

  _post () {
      _start_wifi
  }

  main () {
      if [[ "$2" == "suspend" ]];
         case "$1" in
             pre)
                 _pre
                 ;;
             post)
                 _post
                 ;;
         esac
      fi
  }

  main "$@"

This scripts are intented for local use and hacks, if you want to react to system suspend/hibernation and resume from applications you should use Inhibitor Interface