WiFi Reset Script (for Intel Wireless on Linux)

reset_wifi.sh

#!/bin/bash
# reset_wifi - WiFi Reset Script
# Copyright (C) 2014 Albert Huang.
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
# =====================================================================
# NOTES:
# This is designed for resetting iwlwifi, but it can be easily modified
# to reset other WiFi cards/drivers as well.
# 
# Tested on Linux Mint 17 x64. This should probably work for many other
# Linux distros as well.
# ---------------------------------------------------------------------
# DEVELOPER NOTES:
# This was developed in an attempt to fix iwlwifi issues.
# 
# I concluded that after everything was reset and done, you just have
# to kill wpa_supplicant one more time at the very end to make things
# work. Once that's done, the system may not reconnect for you, but if
# you reconnect yourself, this should work!
# 
# I don't have enough time to test, but another possibility is that
# after waking up, simply killing wpa_supplicant should be enough to
# make things work (without going through the process of unloading
# and reloading iwlwifi). If someone could test this, I would
# appreciate it!
#   Steps to test:
#     (1) Use your laptop normally, suspend and resume when necessary.
#     (2) When the WiFi fails to reconnect RIGHT AFTER RESUME, run:
#           killall -9 wpa_supplicant
#     (3) Try reconnecting manually.
#     (4) If it works, yay! Report it to me and provide the following
#         info:
#           (a) Your Linux distro
#           (b) Architecture (not that it matters, but...)
#           (c) Type of Wifi network you tried to connect to.
#               BE SPECIFIC. If WPA2, is it WPA2-Personal? Or
#               WPA2-Enterprise? (Personal: simple Wifi password.
#               Enterprise: username and password for Wifi.)
#               Other options include WEP, etc. (specify length of
#               password... but don't give me the password!)
#  Thanks!
# 

# chkmod: check if kernel module is loaded or not!
# Usage: chkmod mod_name
# Returns: 0 if found, 1 if not
# Example: chkmod iwlwifi
chkmod() {
	mod_list=`lsmod | cut -f1 -d' '`
	found=`printf "$mod_list" | grep "$1"`
	if [ "$found" = "" ];then
		return 1
	fi
	return 0
}

# chkproc: check if process is running or not!
# Usage: chkproc proc_name
# Returns: 0 if running, 1 if not
# Example: chkproc wpa_supplicant
chkproc() {
	proc_list=`ps -A | tr -s ' ' | cut -f4 -d' '`
	found=`printf "$proc_list" | grep "$1"`
	if [ "$found" = "" ];then
		return 1
	fi
	return 0
}

# showexec: display command to be executed!
# Usage: showexec command...
# Returns: nothing. Just prints "  >> EXEC: command..."
# Example: showexec modprobe iwlwifi
#          Prints:
#            >> EXEC: modprobe iwlwifi
showexec() {
	echo "  >> EXEC: $@"
}

# Check to make sure we have root!
if [ ! "`whoami`" = "root" ];then
	echo " * You need root to proceed. Launching as root via sudo..."
	showexec sudo $0 $@
	sudo $0 $@
	exit $?
else
	echo " * You're root! Proceeding to reset wifi..."
fi

# Remove necessary modules...
MODS="iwldvm iwlwifi mac80211 cfg80211"
for MOD in $MODS; do
	chkmod $MOD
	
	if [ ! "$?" = "0" ];then
		echo " * Skipping kernel module $MOD, since it's not loaded."
		continue
	fi
	
	echo " * Removing kernel module $MOD..."
	showexec rmmod $MOD
	rmmod $MOD
	
	if [ ! "$?" = "0" ];then
		echo "Failed to remove kernel module $MOD. See above for details."
		exit 1
	fi
done

# Pause to let things settle down!
echo " * Waiting 3 seconds for interface to shut off..."
showexec sleep 3s
sleep 3s

# Kill wpa_supplicant daemon...
echo " * Killing wpa_supplicant..."
showexec killall -9 wpa_supplicant
killall -9 wpa_supplicant

chkproc wpa_supplicant
if [ "$?" = "0" ];then
	echo " * ERROR: Unable to kill wpa_supplicant."
	exit 1
fi

# Reload necessary modules!
REL_MODS="iwlwifi"

echo " * Press ENTER now (within 5 seconds) to enter custom"
echo "   module loading options."
read -t 5

if [ "$?" = "0" ];then
	while :; do
		read -p "Enter a module and its options (empty to finish): " mod_opts
		if [[ -z "$mod_opts" ]]; then
			echo " * Exiting custom module loading."
			break
		fi
		showexec modprobe $mod_opts
		modprobe $mod_opts

		if [ ! "$?" = "0" ];then
			echo "Failed to custom load kernel module [$mod_opts]. See above for details."
			echo "To exit, press CTRL-C."
		fi
	done
else
	for MOD in $REL_MODS; do
		echo " * Reloading module: $MOD"
		showexec modprobe $MOD
		
		modprobe $MOD
		
		if [ ! "$?" = "0" ];then
			echo "Failed to load kernel module $MOD. See above for details."
			exit 1
		fi
	done
fi

# Pause to let things settle down!
echo " * Waiting 3 seconds for interface to start working..."
showexec sleep 3s
sleep 3s

# Bring down and bring back up the interface!
INTERFACE="wlan0"

echo " * Bringing network interface $INTERFACE down..."
showexec ifconfig $INTERFACE down
ifconfig $INTERFACE down

echo " * Bringing network interface $INTERFACE up..."
showexec ifconfig $INTERFACE up
ifconfig $INTERFACE up

# Pause to let things settle down!
echo " * Waiting 15 seconds for interface to go up..."
showexec sleep 15s
sleep 15s

# Kill wpa_supplicant daemon...
# NOTE: This final kill seems to be the key to fixing the issue on iwlwifi
echo " * Killing wpa_supplicant..."
showexec killall -9 wpa_supplicant
killall -9 wpa_supplicant

chkproc wpa_supplicant
if [ "$?" = "0" ];then
	echo " * ERROR: Unable to kill wpa_supplicant."
	exit 1
fi

# Yay! Done!
echo ' * All done!'