Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 769 insertions, 0 deletions

diff --git a/tools/testing/ktest/config-bisect.pl b/tools/testing/ktest/config-bisect.pl
new file mode 100755
index 000000000..bee7cb34a
--- /dev/null
+++ b/tools/testing/ktest/config-bisect.pl
@@ -0,0 +1,769 @@
+#!/usr/bin/perl -w
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright 2015 - Steven Rostedt, Red Hat Inc.
+# Copyright 2017 - Steven Rostedt, VMware, Inc.
+#
+
+# usage:
+#  config-bisect.pl [options] good-config bad-config [good|bad]
+#
+
+# Compares a good config to a bad config, then takes half of the diffs
+# and produces a config that is somewhere between the good config and
+# the bad config. That is, the resulting config will start with the
+# good config and will try to make half of the differences of between
+# the good and bad configs match the bad config. It tries because of
+# dependencies between the two configs it may not be able to change
+# exactly half of the configs that are different between the two config
+# files.
+
+# Here's a normal way to use it:
+#
+#  $ cd /path/to/linux/kernel
+#  $ config-bisect.pl /path/to/good/config /path/to/bad/config
+
+# This will now pull in good config (blowing away .config in that directory
+# so do not make that be one of the good or bad configs), and then
+# build the config with "make oldconfig" to make sure it matches the
+# current kernel. It will then store the configs in that result for
+# the good config. It does the same for the bad config as well.
+# The algorithm will run, merging half of the differences between
+# the two configs and building them with "make oldconfig" to make sure
+# the result changes (dependencies may reset changes the tool had made).
+# It then copies the result of its good config to /path/to/good/config.tmp
+# and the bad config to /path/to/bad/config.tmp (just appends ".tmp" to the
+# files passed in). And the ".config" that you should test will be in
+# directory
+
+# After the first run, determine if the result is good or bad then
+# run the same command appending the result
+
+# For good results:
+#  $ config-bisect.pl /path/to/good/config /path/to/bad/config good
+
+# For bad results:
+#  $ config-bisect.pl /path/to/good/config /path/to/bad/config bad
+
+# Do not change the good-config or bad-config, config-bisect.pl will
+# copy the good-config to a temp file with the same name as good-config
+# but with a ".tmp" after it. It will do the same with the bad-config.
+
+# If "good" or "bad" is not stated at the end, it will copy the good and
+# bad configs to the .tmp versions. If a .tmp version already exists, it will
+# warn before writing over them (-r will not warn, and just write over them).
+# If the last config is labeled "good", then it will copy it to the good .tmp
+# version. If the last config is labeled "bad", it will copy it to the bad
+# .tmp version. It will continue this until it can not merge the two any more
+# without the result being equal to either the good or bad .tmp configs.
+
+my $start = 0;
+my $val = "";
+
+my $pwd = `pwd`;
+chomp $pwd;
+my $tree = $pwd;
+my $build;
+
+my $output_config;
+my $reset_bisect;
+
+sub usage {
+    print << "EOF"
+
+usage: config-bisect.pl [-l linux-tree][-b build-dir] good-config bad-config [good|bad]
+  -l [optional] define location of linux-tree (default is current directory)
+  -b [optional] define location to build (O=build-dir) (default is linux-tree)
+  good-config the config that is considered good
+  bad-config the config that does not work
+  "good" add this if the last run produced a good config
+  "bad" add this if the last run produced a bad config
+  If "good" or "bad" is not specified, then it is the start of a new bisect
+
+  Note, each run will create copy of good and bad configs with ".tmp" appended.
+
+EOF
+;
+
+    exit(-1);
+}
+
+sub doprint {
+    print @_;
+}
+
+sub dodie {
+    doprint "CRITICAL FAILURE... ", @_, "\n";
+
+    die @_, "\n";
+}
+
+sub expand_path {
+    my ($file) = @_;
+
+    if ($file =~ m,^/,) {
+	return $file;
+    }
+    return "$pwd/$file";
+}
+
+sub read_prompt {
+    my ($cancel, $prompt) = @_;
+
+    my $ans;
+
+    for (;;) {
+	if ($cancel) {
+	    print "$prompt [y/n/C] ";
+	} else {
+	    print "$prompt [y/N] ";
+	}
+	$ans = <STDIN>;
+	chomp $ans;
+	if ($ans =~ /^\s*$/) {
+	    if ($cancel) {
+		$ans = "c";
+	    } else {
+		$ans = "n";
+	    }
+	}
+	last if ($ans =~ /^y$/i || $ans =~ /^n$/i);
+	if ($cancel) {
+	    last if ($ans =~ /^c$/i);
+	    print "Please answer either 'y', 'n' or 'c'.\n";
+	} else {
+	    print "Please answer either 'y' or 'n'.\n";
+	}
+    }
+    if ($ans =~ /^c/i) {
+	exit;
+    }
+    if ($ans !~ /^y$/i) {
+	return 0;
+    }
+    return 1;
+}
+
+sub read_yn {
+    my ($prompt) = @_;
+
+    return read_prompt 0, $prompt;
+}
+
+sub read_ync {
+    my ($prompt) = @_;
+
+    return read_prompt 1, $prompt;
+}
+
+sub run_command {
+    my ($command, $redirect) = @_;
+    my $start_time;
+    my $end_time;
+    my $dord = 0;
+    my $pid;
+
+    $start_time = time;
+
+    doprint("$command ... ");
+
+    $pid = open(CMD, "$command 2>&1 |") or
+	dodie "unable to exec $command";
+
+    if (defined($redirect)) {
+	open (RD, ">$redirect") or
+	    dodie "failed to write to redirect $redirect";
+	$dord = 1;
+    }
+
+    while (<CMD>) {
+	print RD  if ($dord);
+    }
+
+    waitpid($pid, 0);
+    my $failed = $?;
+
+    close(CMD);
+    close(RD)  if ($dord);
+
+    $end_time = time;
+    my $delta = $end_time - $start_time;
+
+    if ($delta == 1) {
+	doprint "[1 second] ";
+    } else {
+	doprint "[$delta seconds] ";
+    }
+
+    if ($failed) {
+	doprint "FAILED!\n";
+    } else {
+	doprint "SUCCESS\n";
+    }
+
+    return !$failed;
+}
+
+###### CONFIG BISECT ######
+
+# config_ignore holds the configs that were set (or unset) for
+# a good config and we will ignore these configs for the rest
+# of a config bisect. These configs stay as they were.
+my %config_ignore;
+
+# config_set holds what all configs were set as.
+my %config_set;
+
+# config_off holds the set of configs that the bad config had disabled.
+# We need to record them and set them in the .config when running
+# olddefconfig, because olddefconfig keeps the defaults.
+my %config_off;
+
+# config_off_tmp holds a set of configs to turn off for now
+my @config_off_tmp;
+
+# config_list is the set of configs that are being tested
+my %config_list;
+my %null_config;
+
+my %dependency;
+
+my $make;
+
+sub make_oldconfig {
+
+    if (!run_command "$make olddefconfig") {
+	# Perhaps olddefconfig doesn't exist in this version of the kernel
+	# try oldnoconfig
+	doprint "olddefconfig failed, trying make oldnoconfig\n";
+	if (!run_command "$make oldnoconfig") {
+	    doprint "oldnoconfig failed, trying yes '' | make oldconfig\n";
+	    # try a yes '' | oldconfig
+	    run_command "yes '' | $make oldconfig" or
+		dodie "failed make config oldconfig";
+	}
+    }
+}
+
+sub assign_configs {
+    my ($hash, $config) = @_;
+
+    doprint "Reading configs from $config\n";
+
+    open (IN, $config)
+	or dodie "Failed to read $config";
+
+    while (<IN>) {
+	chomp;
+	if (/^((CONFIG\S*)=.*)/) {
+	    ${$hash}{$2} = $1;
+	} elsif (/^(# (CONFIG\S*) is not set)/) {
+	    ${$hash}{$2} = $1;
+	}
+    }
+
+    close(IN);
+}
+
+sub process_config_ignore {
+    my ($config) = @_;
+
+    assign_configs \%config_ignore, $config;
+}
+
+sub get_dependencies {
+    my ($config) = @_;
+
+    my $arr = $dependency{$config};
+    if (!defined($arr)) {
+	return ();
+    }
+
+    my @deps = @{$arr};
+
+    foreach my $dep (@{$arr}) {
+	print "ADD DEP $dep\n";
+	@deps = (@deps, get_dependencies $dep);
+    }
+
+    return @deps;
+}
+
+sub save_config {
+    my ($pc, $file) = @_;
+
+    my %configs = %{$pc};
+
+    doprint "Saving configs into $file\n";
+
+    open(OUT, ">$file") or dodie "Can not write to $file";
+
+    foreach my $config (keys %configs) {
+	print OUT "$configs{$config}\n";
+    }
+    close(OUT);
+}
+
+sub create_config {
+    my ($name, $pc) = @_;
+
+    doprint "Creating old config from $name configs\n";
+
+    save_config $pc, $output_config;
+
+    make_oldconfig;
+}
+
+# compare two config hashes, and return configs with different vals.
+# It returns B's config values, but you can use A to see what A was.
+sub diff_config_vals {
+    my ($pa, $pb) = @_;
+
+    # crappy Perl way to pass in hashes.
+    my %a = %{$pa};
+    my %b = %{$pb};
+
+    my %ret;
+
+    foreach my $item (keys %a) {
+	if (defined($b{$item}) && $b{$item} ne $a{$item}) {
+	    $ret{$item} = $b{$item};
+	}
+    }
+
+    return %ret;
+}
+
+# compare two config hashes and return the configs in B but not A
+sub diff_configs {
+    my ($pa, $pb) = @_;
+
+    my %ret;
+
+    # crappy Perl way to pass in hashes.
+    my %a = %{$pa};
+    my %b = %{$pb};
+
+    foreach my $item (keys %b) {
+	if (!defined($a{$item})) {
+	    $ret{$item} = $b{$item};
+	}
+    }
+
+    return %ret;
+}
+
+# return if two configs are equal or not
+# 0 is equal +1 b has something a does not
+# +1 if a and b have a different item.
+# -1 if a has something b does not
+sub compare_configs {
+    my ($pa, $pb) = @_;
+
+    my %ret;
+
+    # crappy Perl way to pass in hashes.
+    my %a = %{$pa};
+    my %b = %{$pb};
+
+    foreach my $item (keys %b) {
+	if (!defined($a{$item})) {
+	    return 1;
+	}
+	if ($a{$item} ne $b{$item}) {
+	    return 1;
+	}
+    }
+
+    foreach my $item (keys %a) {
+	if (!defined($b{$item})) {
+	    return -1;
+	}
+    }
+
+    return 0;
+}
+
+sub process_failed {
+    my ($config) = @_;
+
+    doprint "\n\n***************************************\n";
+    doprint "Found bad config: $config\n";
+    doprint "***************************************\n\n";
+}
+
+sub process_new_config {
+    my ($tc, $nc, $gc, $bc) = @_;
+
+    my %tmp_config = %{$tc};
+    my %good_configs = %{$gc};
+    my %bad_configs = %{$bc};
+
+    my %new_configs;
+
+    my $runtest = 1;
+    my $ret;
+
+    create_config "tmp_configs", \%tmp_config;
+    assign_configs \%new_configs, $output_config;
+
+    $ret = compare_configs \%new_configs, \%bad_configs;
+    if (!$ret) {
+	doprint "New config equals bad config, try next test\n";
+	$runtest = 0;
+    }
+
+    if ($runtest) {
+	$ret = compare_configs \%new_configs, \%good_configs;
+	if (!$ret) {
+	    doprint "New config equals good config, try next test\n";
+	    $runtest = 0;
+	}
+    }
+
+    %{$nc} = %new_configs;
+
+    return $runtest;
+}
+
+sub convert_config {
+    my ($config) = @_;
+
+    if ($config =~ /^# (.*) is not set/) {
+	$config = "$1=n";
+    }
+
+    $config =~ s/^CONFIG_//;
+    return $config;
+}
+
+sub print_config {
+    my ($sym, $config) = @_;
+
+    $config = convert_config $config;
+    doprint "$sym$config\n";
+}
+
+sub print_config_compare {
+    my ($good_config, $bad_config) = @_;
+
+    $good_config = convert_config $good_config;
+    $bad_config = convert_config $bad_config;
+
+    my $good_value = $good_config;
+    my $bad_value = $bad_config;
+    $good_value =~ s/(.*)=//;
+    my $config = $1;
+
+    $bad_value =~ s/.*=//;
+
+    doprint " $config $good_value -> $bad_value\n";
+}
+
+# Pass in:
+# $phalf: half of the configs names you want to add
+# $oconfigs: The orginial configs to start with
+# $sconfigs: The source to update $oconfigs with (from $phalf)
+# $which: The name of which half that is updating (top / bottom)
+# $type: The name of the source type (good / bad)
+sub make_half {
+    my ($phalf, $oconfigs, $sconfigs, $which, $type) = @_;
+
+    my @half = @{$phalf};
+    my %orig_configs = %{$oconfigs};
+    my %source_configs = %{$sconfigs};
+
+    my %tmp_config = %orig_configs;
+
+    doprint "Settings bisect with $which half of $type configs:\n";
+    foreach my $item (@half) {
+	doprint "Updating $item to $source_configs{$item}\n";
+	$tmp_config{$item} = $source_configs{$item};
+    }
+
+    return %tmp_config;
+}
+
+sub run_config_bisect {
+    my ($pgood, $pbad) = @_;
+
+    my %good_configs = %{$pgood};
+    my %bad_configs = %{$pbad};
+
+    my %diff_configs = diff_config_vals \%good_configs, \%bad_configs;
+    my %b_configs = diff_configs \%good_configs, \%bad_configs;
+    my %g_configs = diff_configs \%bad_configs, \%good_configs;
+
+    # diff_arr is what is in both good and bad but are different (y->n)
+    my @diff_arr = keys %diff_configs;
+    my $len_diff = $#diff_arr + 1;
+
+    # b_arr is what is in bad but not in good (has depends)
+    my @b_arr = keys %b_configs;
+    my $len_b = $#b_arr + 1;
+
+    # g_arr is what is in good but not in bad
+    my @g_arr = keys %g_configs;
+    my $len_g = $#g_arr + 1;
+
+    my $runtest = 0;
+    my %new_configs;
+    my $ret;
+
+    # Look at the configs that are different between good and bad.
+    # This does not include those that depend on other configs
+    #  (configs depending on other configs that are not set would
+    #   not show up even as a "# CONFIG_FOO is not set"
+
+
+    doprint "# of configs to check:             $len_diff\n";
+    doprint "# of configs showing only in good: $len_g\n";
+    doprint "# of configs showing only in bad:  $len_b\n";
+
+    if ($len_diff > 0) {
+	# Now test for different values
+
+	doprint "Configs left to check:\n";
+	doprint "  Good Config\t\t\tBad Config\n";
+	doprint "  -----------\t\t\t----------\n";
+	foreach my $item (@diff_arr) {
+	    doprint "  $good_configs{$item}\t$bad_configs{$item}\n";
+	}
+
+	my $half = int($#diff_arr / 2);
+	my @tophalf = @diff_arr[0 .. $half];
+
+	doprint "Set tmp config to be good config with some bad config values\n";
+
+	my %tmp_config = make_half \@tophalf, \%good_configs,
+	    \%bad_configs, "top", "bad";
+
+	$runtest = process_new_config \%tmp_config, \%new_configs,
+			    \%good_configs, \%bad_configs;
+
+	if (!$runtest) {
+	    doprint "Set tmp config to be bad config with some good config values\n";
+
+	    my %tmp_config = make_half \@tophalf, \%bad_configs,
+		\%good_configs, "top", "good";
+
+	    $runtest = process_new_config \%tmp_config, \%new_configs,
+		\%good_configs, \%bad_configs;
+	}
+    }
+
+    if (!$runtest && $len_diff > 0) {
+	# do the same thing, but this time with bottom half
+
+	my $half = int($#diff_arr / 2);
+	my @bottomhalf = @diff_arr[$half+1 .. $#diff_arr];
+
+	doprint "Set tmp config to be good config with some bad config values\n";
+
+	my %tmp_config = make_half \@bottomhalf, \%good_configs,
+	    \%bad_configs, "bottom", "bad";
+
+	$runtest = process_new_config \%tmp_config, \%new_configs,
+			    \%good_configs, \%bad_configs;
+
+	if (!$runtest) {
+	    doprint "Set tmp config to be bad config with some good config values\n";
+
+	    my %tmp_config = make_half \@bottomhalf, \%bad_configs,
+		\%good_configs, "bottom", "good";
+
+	    $runtest = process_new_config \%tmp_config, \%new_configs,
+		\%good_configs, \%bad_configs;
+	}
+    }
+
+    if ($runtest) {
+	make_oldconfig;
+	doprint "READY TO TEST .config IN $build\n";
+	return 0;
+    }
+
+    doprint "\n%%%%%%%% FAILED TO FIND SINGLE BAD CONFIG %%%%%%%%\n";
+    doprint "Hmm, can't make any more changes without making good == bad?\n";
+    doprint "Difference between good (+) and bad (-)\n";
+
+    foreach my $item (keys %bad_configs) {
+	if (!defined($good_configs{$item})) {
+	    print_config "-", $bad_configs{$item};
+	}
+    }
+
+    foreach my $item (keys %good_configs) {
+	next if (!defined($bad_configs{$item}));
+	if ($good_configs{$item} ne $bad_configs{$item}) {
+	    print_config_compare $good_configs{$item}, $bad_configs{$item};
+	}
+    }
+
+    foreach my $item (keys %good_configs) {
+	if (!defined($bad_configs{$item})) {
+	    print_config "+", $good_configs{$item};
+	}
+    }
+    return -1;
+}
+
+sub config_bisect {
+    my ($good_config, $bad_config) = @_;
+    my $ret;
+
+    my %good_configs;
+    my %bad_configs;
+    my %tmp_configs;
+
+    doprint "Run good configs through make oldconfig\n";
+    assign_configs \%tmp_configs, $good_config;
+    create_config "$good_config", \%tmp_configs;
+    assign_configs \%good_configs, $output_config;
+
+    doprint "Run bad configs through make oldconfig\n";
+    assign_configs \%tmp_configs, $bad_config;
+    create_config "$bad_config", \%tmp_configs;
+    assign_configs \%bad_configs, $output_config;
+
+    save_config \%good_configs, $good_config;
+    save_config \%bad_configs, $bad_config;
+
+    return run_config_bisect \%good_configs, \%bad_configs;
+}
+
+while ($#ARGV >= 0) {
+    if ($ARGV[0] !~ m/^-/) {
+	last;
+    }
+    my $opt = shift @ARGV;
+
+    if ($opt eq "-b") {
+	$val = shift @ARGV;
+	if (!defined($val)) {
+	    die "-b requires value\n";
+	}
+	$build = $val;
+    }
+
+    elsif ($opt eq "-l") {
+	$val = shift @ARGV;
+	if (!defined($val)) {
+	    die "-l requires value\n";
+	}
+	$tree = $val;
+    }
+
+    elsif ($opt eq "-r") {
+	$reset_bisect = 1;
+    }
+
+    elsif ($opt eq "-h") {
+	usage;
+    }
+
+    else {
+	die "Unknown option $opt\n";
+    }
+}
+
+$build = $tree if (!defined($build));
+
+$tree = expand_path $tree;
+$build = expand_path $build;
+
+if ( ! -d $tree ) {
+    die "$tree not a directory\n";
+}
+
+if ( ! -d $build ) {
+    die "$build not a directory\n";
+}
+
+usage if $#ARGV < 1;
+
+if ($#ARGV == 1) {
+    $start = 1;
+} elsif ($#ARGV == 2) {
+    $val = $ARGV[2];
+    if ($val ne "good" && $val ne "bad") {
+	die "Unknown command '$val', bust be either \"good\" or \"bad\"\n";
+    }
+} else {
+    usage;
+}
+
+my $good_start = expand_path $ARGV[0];
+my $bad_start = expand_path $ARGV[1];
+
+my $good = "$good_start.tmp";
+my $bad = "$bad_start.tmp";
+
+$make = "make";
+
+if ($build ne $tree) {
+    $make = "make O=$build"
+}
+
+$output_config = "$build/.config";
+
+if ($start) {
+    if ( ! -f $good_start ) {
+	die "$good_start not found\n";
+    }
+    if ( ! -f $bad_start ) {
+	die "$bad_start not found\n";
+    }
+    if ( -f $good || -f $bad ) {
+	my $p = "";
+
+	if ( -f $good ) {
+	    $p = "$good exists\n";
+	}
+
+	if ( -f $bad ) {
+	    $p = "$p$bad exists\n";
+	}
+
+	if (!defined($reset_bisect)) {
+	    if (!read_yn "${p}Overwrite and start new bisect anyway?") {
+		exit (-1);
+	    }
+	}
+    }
+    run_command "cp $good_start $good" or die "failed to copy to $good\n";
+    run_command "cp $bad_start $bad" or die "failed to copy to $bad\n";
+} else {
+    if ( ! -f $good ) {
+	die "Can not find file $good\n";
+    }
+    if ( ! -f $bad ) {
+	die "Can not find file $bad\n";
+    }
+    if ($val eq "good") {
+	run_command "cp $output_config $good" or die "failed to copy $output_config to $good\n";
+    } elsif ($val eq "bad") {
+	run_command "cp $output_config $bad" or die "failed to copy $output_config to $bad\n";
+    }
+}
+
+chdir $tree || die "can't change directory to $tree";
+
+my $ret = config_bisect $good, $bad;
+
+if (!$ret) {
+    exit(0);
+}
+
+if ($ret > 0) {
+    doprint "Cleaning temp files\n";
+    run_command "rm $good";
+    run_command "rm $bad";
+    exit(1);
+} else {
+    doprint "See good and bad configs for details:\n";
+    doprint "good: $good\n";
+    doprint "bad:  $bad\n";
+    doprint "%%%%%%%% FAILED TO FIND SINGLE BAD CONFIG %%%%%%%%\n";
+}
+exit(2);