From 7a77fbe36acf1d3ce2ce2361070061af1685a085 Mon Sep 17 00:00:00 2001
From: Matej Kafka <git@a-n.cc>
Date: Mon, 26 Apr 2021 05:33:40 +0200
Subject: [PATCH] #31 Rewrite cleanup_crash.sh to work more reliably and match
 new cgroup naming scheme

Sidenote: Wow, do people actually willingly write scripts in bash? Is that a case of Stockholm syndrome?

closes #31
---
 src/cleanup_crash.sh | 103 ++++++++++++++++++++++++++-----------------
 1 file changed, 62 insertions(+), 41 deletions(-)

diff --git a/src/cleanup_crash.sh b/src/cleanup_crash.sh
index 973b13f0..e221dbfa 100644
--- a/src/cleanup_crash.sh
+++ b/src/cleanup_crash.sh
@@ -1,53 +1,74 @@
-#!/bin/bash
-
-#if [ -z "$1" ] then
-#    CG_NAME="demos"
-#else
-#    CG_NAME="$1"
-#fi
-
-FREEZER="/sys/fs/cgroup/freezer/demos"
-CPUSET="/sys/fs/cgroup/cpuset/demos"
-UNIFIED="/sys/fs/cgroup/unified/user.slice/user-1000.slice/demos"
-
-# kill all procs in freezer
-procs_files=($(find "$FREEZER" -name *.procs))
-
-for i in "${procs_files[@]}"
-do
-    while read line
-    do
-        if [ $line != $$ ]
-        then
-            kill $line
-        fi
-    done < "$i"
-done
+#!/usr/bin/env bash
+set -Eeuo pipefail
+shopt -s extglob nullglob globstar
+
+# NOTE: hybrid cgroup mode is assumed here;
+#  after switch to unified cgroups, this will need to be updated
+
+if [[ $EUID > 0 ]]; then
+    >&2 echo "Please run this script as root"
+    exit 1
+fi
 
-# unfreeze all freezers
-freezers=($(find "$FREEZER" -name *freezer.state))
 
-for i in "${freezers[@]}"
-do
-    #echo "$i"
-    echo "THAWED" > "$i"
+# stop all running demos instances
+# found using the cgroup name, which includes scheduler PID
+freezer=(/sys/fs/cgroup/freezer/demos-+([0-9]))
+for pid in "${freezer[@]##*-}"; do
+    if [[ ! -d "/proc/$pid" ]]; then continue; fi
+    echo "Stopping demos instance: $pid"
+    kill -INT "$pid"
 done
+# give time to demos instances to exit; ideally, this should be a `wait` with timeout
+#  (in case the scheduler process is unresponsive)
+sleep 0.1
+
 
-# remove all cgroups
-d="/*"
-rmdir `ls -d $FREEZER$d$d/ 2>/dev/null ` 2>/dev/null
-rmdir `ls -d $FREEZER$d/ 2>/dev/null ` 2>/dev/null
-rmdir `ls -d $CPUSET$d$d/ 2>/dev/null ` 2>/dev/null
-rmdir `ls -d $CPUSET$d/ 2>/dev/null ` 2>/dev/null
-rmdir `ls -d $UNIFIED$d$d/ 2>/dev/null ` 2>/dev/null
-rmdir `ls -d $UNIFIED$d/ 2>/dev/null ` 2>/dev/null
+# find all demos cgroups (demos-<scheduler_pid>)
+freezer=(/sys/fs/cgroup/freezer/demos-+([0-9]))
+cpuset=(/sys/fs/cgroup/cpuset/demos-+([0-9]))
+unified=(
+    /sys/fs/cgroup/unified/demos-+([0-9])
+    /sys/fs/cgroup/unified/user.slice/user-+([0-9]).slice/*/demos-+([0-9])
+    /sys/fs/cgroup/unified/user.slice/user-+([0-9]).slice/*/run-*/demos-+([0-9])
+)
+echo "Found freezer:" "${freezer[@]}"
+echo "Found cpuset:" "${cpuset[@]}"
+echo "Found unified:" "${unified[@]}"
+
+if [[ ${#freezer[@]} -gt 0 ]]; then
+    # https://askubuntu.com/questions/343727/filenames-with-spaces-breaking-for-loop-find-command
+    # kill all processes in demos freezers
+    find "${freezer[@]}" -name 'cgroup.procs' -print0 | while IFS= read -r -d '' proc_file; do
+        while IFS= read -r line; do
+            echo "Killing process: $line"
+            kill $line
+        done <"$proc_file"
+    done
+
+    # unfreeze all demos freezers - this allows the processes to end
+    find "${freezer[@]}" -name 'freezer.state' -print0 | while IFS= read -r -d '' state_file; do
+        echo "THAWED" >"$state_file"
+    done
+fi
+
+# remove all demos cgroups
+for cgdir in "${freezer[@]}" "${cpuset[@]}" "${unified[@]}"; do
+    # first, delete grandchildren (proc cgroups), then delete children (partition cgroups), then whole cgroup
+    echo "Removing cgroup: $cgdir"
+    # `|| true`, because under systemd-run, cgroup root seems to be automatically deleted
+    #  with last child and `find` then cannot delete it and complains
+    find "$cgdir" -maxdepth 2 -type d -delete || true
+done
 
 
 # reset CPU frequency scaling state
 if [[ -f "/sys/devices/system/cpu/intel_pstate/status" ]]; then
     # for Intel, it is enough to reset driver to active mode
-    echo "active" > "/sys/devices/system/cpu/intel_pstate/status"
+    echo "Resetting intel_pstate driver to 'active' state"
+    echo "active" >"/sys/devices/system/cpu/intel_pstate/status"
 elif [[ -d "/sys/devices/system/cpu/cpufreq" ]]; then
+    echo "Resetting cpufreq governors to 'schedutil'"
     # for others, switch all policies to schedutil (and hope that was the default)
-    echo "schedutil" | tee /sys/devices/system/cpu/cpufreq/policy*/scaling_governor
+    echo "schedutil" | tee /sys/devices/system/cpu/cpufreq/policy*/scaling_governor >/dev/null
 fi