filter.pl

#!/usr/bin/perl
# usage:
# filter.pl <stacktraces file>
# stacktraces file is to be acquired by "foreach bt" in crash

my $dbg_filter = 0;
my $use_filter = 1;

if ( scalar (@ARGV) == 0 || ! -e $ARGV[0] ) {
    print "backtraces file name expected\n";
    exit 1;
}

for ($idx=1; $idx < scalar(@ARGV); ++$idx) {
    $dbg_filter = 1 if ($ARGV[$idx] eq "-d");
    $use_filter = 0 if ($ARGV[$idx] eq "-n");
}

my @all_trc=();
my @all_names=();
my @trc=();
my $bt_lines = 0, my $fru=0;

open (FH, $ARGV[0]) or die "trying";

while (<FH>) {
    chomp;
    next if ($_ eq "");
    if ( m/PID.*COMMAND/ ) {
        &process_one();
        @trc = ();
        $bt_lines = 0;
    }
    ++$bt_lines if ($_ =~ m|^\s*#[0-9]+\s|);
    push @trc, $_;
}

#final stack:
process_one();

# print all names and stacks
for ($idx=0; $idx < scalar(@all_trc); ++$idx) {
    my @names = @ {$all_names[$idx]};
    foreach (@names){
        print "$_\n";
    }
    my @stk = @{$all_trc[$idx]};
    foreach (@stk) {
        print "$_\n";
    }
    print "\n";
}

sub process_one() {
    $fru = 0;
    $fru = &filter() if $use_filter;
    if ( $fru ) {
        if ($dbg_filter && scalar(@trc) != 0) {
            print "${trc[0]} - filtered out ($fru)\n";
        }
    } else {
        $fru = &find_same();
        if ($fru>=0) {
            push @{ $all_names[$fru] }, $trc[0];
        } else {
            my @names=();
            push @all_trc, [ @trc ];
            push @all_names, [ @names ];
        }
    }
}

sub find_same {
    my $idx, my $ln, my $same;
    for($idx=0; $idx < scalar(@all_trc); ++$idx) {
        my @stk = @{$all_trc[$idx]};
        next if scalar(@stk) != scalar(@trc);
        $same = $idx;
        for ($ln=1; $ln < scalar(@stk); ++$ln) {
            my $stkln = @stk[$ln];
            my $trcln = @trc[$ln];
            $stkln =~ s/\[[0-9a-f]{16}\]//;
            $trcln =~ s/\[[0-9a-f]{16}\]//;
            next if ( ($stkln !~ m/^\s*#[0-9]/) && ($trcln !~ m/^\s*#[0-9]/) );
            if ( $stkln ne $trcln ) {
                $same = -1;
                last; # for each trace line
            }
        }
        if ($same >= 0) {
            # print "match: '${trc[0]}' vs '${stk[0]}'\n";
            return $same;
        }
    }
    return -1;
}

sub filter {
    # small stacks
    if (scalar(@trc)<=6) { return 1 }
    if ($bt_lines < 3) {return 13}
    # futexes
    foreach ( @trc ) {
        if (m/futex/) { return 2 }
        if (m/pipe_read/) {return 3}
        if (m/sys_wait/) {return 4}
        if (m/poll/) {return 5}
        if (m/kthread_stop/) {return 6}
        if (m/sys_exit_group/) {return 7}
        if (m/"sleep"/) {return 8}
        if (m/"tail"/) {return 9}
        if (m/vfs_read/) {return 10}
        if (m/tty_ioctl/) {return 11}
        if (m/intel_idle/) {return 12}
        if (m/bash/) {return 14}
        if (m/nanosleep/) {return 15}
    }
    return 0;
}