#!/bin/bash
#
# reset-trace - reset state of tracing, disabling all tracing.
# Written for Linux.
#
# If a bcc tool crashed and you suspect tracing is partially enabled, you
# can use this tool to reset the state of tracing, disabling anything still
# enabled. Only use this tool in the case of error, and, consider filing a
# bcc ticket so we can fix the error.
#
# bcc-used tracing facilities are reset. Other tracing facilities (ftrace) are
# checked, and if not in an expected state, a note is printed. All tracing
# files can be reset with -F for force, but this will interfere with any other
# running tracing sessions (eg, ftrace).
#
# USAGE: ./reset-trace [-Fhqv]
#
# REQUIREMENTS: debugfs mounted on /sys/kernel/debug
#
# COPYRIGHT: Copyright (c) 2016 Brendan Gregg.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 20-Jul-2014 Brendan Gregg Created this.
# 18-Oct-2016 " " Updated for bcc use.
tracing=/sys/kernel/debug/tracing
opt_force=0; opt_verbose=0; opt_quiet=0
function usage {
cat <<-END >&2
USAGE: reset-trace [-Fhqv]
-F # force: reset all tracing files
-v # verbose: print details while working
-h # this usage message
-q # quiet: no output
eg,
reset-trace # disable semi-enabled tracing
END
exit
}
function die {
echo >&2 "$@"
exit 1
}
function vecho {
(( ! opt_verbose )) && return
echo "$@"
}
function writefile {
file=$1
write=$2
if [[ ! -w $file ]]; then
echo >&2 "WARNING: file $file not writable/exists. Skipping."
return
fi
vecho "Checking $PWD/$file"
contents=$(grep -v '^#' $file)
if [[ "$contents" != "$expected" ]]; then
(( ! opt_quiet )) && echo "Needed to reset $PWD/$file"
vecho "$file, before (line enumerated):"
(( opt_verbose )) && cat -nv $file
cmd="echo $write > $file"
if ! eval "$cmd"; then
echo >&2 "WARNING: command failed \"$cmd\"." \
"bcc still running? Continuing."
fi
vecho "$file, after (line enumerated):"
(( opt_verbose )) && cat -nv $file
vecho
fi
}
# only write when force is used
function checkfile {
file=$1
write=$2
expected=$3
if [[ ! -e $file ]]; then
echo >&2 "WARNING: file $file doesn't exist. Skipping."
return
fi
if (( opt_force )); then
writefile $file $write
return
fi
(( opt_quiet )) && return
vecho "Checking $PWD/$file"
contents=$(grep -v '^#' $file)
if [[ "$contents" != "$expected" ]]; then
echo "Noticed unrelated tracing file $PWD/$file isn't set as" \
"expected. Not resetting (-F to force, -v for verbose)."
vecho "Contents of $file is (line enumerated):"
(( opt_verbose )) && cat -nv $file
vecho "Expected \"$expected\"."
fi
}
### process options
while getopts Fhqv opt
do
case $opt in
F) opt_force=1 ;;
q) opt_quiet=1 ;;
v) opt_verbose=1 ;;
h|?) usage ;;
esac
done
shift $(( $OPTIND - 1 ))
### reset tracing state
vecho "Resetting tracing state..."
vecho
cd $tracing || die "ERROR: accessing tracing. Root user? /sys/kernel/debug?"
# files bcc uses
writefile kprobe_events "" ""
writefile uprobe_events "" ""
writefile trace "" "" # clears trace_pipe
# non-bcc files
checkfile current_tracer nop nop
checkfile set_ftrace_filter "" ""
checkfile set_graph_function "" ""
checkfile set_ftrace_pid "" "no pid"
checkfile events/enable 0 0
checkfile tracing_thresh 0 0
checkfile tracing_on 1 1
vecho
vecho "Done."
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