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Date: Tue, 16 Dec 2008 12:52:49 +0100
From: Vegard Nossum <vegard.nossum@...il.com>
To: Sam Ravnborg <sam@...nborg.org>
Cc: Adrian Bunk <bunk@...nel.org>,
Pekka Enberg <penberg@...helsinki.fi>,
Nick Andrew <nick@...k-andrew.net>,
Matthew Wilcox <matthew@....cx>,
Jan Engelhardt <jengelh@...putergmbh.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] headerdep: a tool for detecting inclusion cycles in
header files
On Sat, Dec 13, 2008 at 11:22 PM, Sam Ravnborg <sam@...nborg.org> wrote:
> I tried to apply it and saw following output:
> In file included from linux/mmzone.h,
> from linux/topology.h
> from linux/mmzone.h
> from linux/gfp.h
> from linux/slub_def.h
> from linux/slab.h
> from linux/percpu.h
> from asm-generic/irq_regs.h
> include/asm-xtensa/irq_regs.h: warning: recursive header inclusion
>
> But looking at the file (include/asm-xtensa/irq_regs.h) did
> not help me understand where to look to fix it.
The program was run with include/asm-xtensa/irq_regs.h as input. So it
displays the whole chain of inclusion. The cycle is just the upper part:
> In file included from linux/mmzone.h,
> from linux/topology.h
> from linux/mmzone.h
...so that's where to look in general. I checked mmzone.h and topology.h,
and they do indeed include each other.
>
> Can you pinpoint the culprint better so this is becoming useful?
Line numbers would be nice, I agree. We can also have just the cycle stand
out a bit more. This is the new format:
$ perl scripts/headerdep.pl include/asm-xtensa/irq_regs.h
In file included from linux/mmzone.h,
from linux/topology.h:32
from linux/mmzone.h:763 <-- here
from linux/gfp.h:4
from linux/slub_def.h:10
from linux/slab.h:152
from linux/percpu.h:5
from asm-generic/irq_regs.h:15
include/asm-xtensa/irq_regs.h:1: warning: recursive header inclusion
> I would also like to see this integrated with checkincludes.pl
> as both script do some simple static checks of the header files.
>
> Additional bonus if we can reuse this to do better check of
> our exported headers.
This one is probably a bit too noisy? But if we can eliminate the existing
cycles, it would be nice, I agree. Thanks for the feedback! :)
Vegard
>From 24d6e19682ce2b7ffa6c032fb0199dbcabcc1a5b Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@...il.com>
Date: Tue, 16 Dec 2008 12:33:43 +0100
Subject: [PATCH] headerdep: add a tool to detect inclusion cycles in header files #3
Signed-off-by: Vegard Nossum <vegard.nossum@...il.com>
---
Makefile | 7 ++-
scripts/headerdep.pl | 193 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 199 insertions(+), 1 deletions(-)
create mode 100755 scripts/headerdep.pl
diff --git a/Makefile b/Makefile
index 9a49960..d4b13d9 100644
--- a/Makefile
+++ b/Makefile
@@ -1022,6 +1022,10 @@ include/linux/version.h: $(srctree)/Makefile FORCE
include/linux/utsrelease.h: include/config/kernel.release FORCE
$(call filechk,utsrelease.h)
+PHONY += headerdep
+headerdep:
+ @find include/ -name '*.h' | xargs --max-args 1 scripts/headerdep.pl
+
# ---------------------------------------------------------------------------
PHONY += depend dep
@@ -1270,7 +1274,8 @@ help:
@echo ' versioncheck - Sanity check on version.h usage'
@echo ' includecheck - Check for duplicate included header files'
@echo ' export_report - List the usages of all exported symbols'
- @echo ' headers_check - Sanity check on exported headers'; \
+ @echo ' headers_check - Sanity check on exported headers'
+ @echo ' headerdep - Detect inclusion cycles in headers'; \
echo ''
@echo 'Kernel packaging:'
@$(MAKE) $(build)=$(package-dir) help
diff --git a/scripts/headerdep.pl b/scripts/headerdep.pl
new file mode 100755
index 0000000..b3265f6
--- /dev/null
+++ b/scripts/headerdep.pl
@@ -0,0 +1,193 @@
+#! /usr/bin/perl
+#
+# Detect cycles in the header file dependency graph
+# Vegard Nossum <vegardno@....uio.no>
+#
+
+use strict;
+use warnings;
+
+use Getopt::Long;
+
+my $opt_all;
+my @opt_include;
+my $opt_graph;
+
+&Getopt::Long::Configure(qw(bundling pass_through));
+&GetOptions(
+ help => \&help,
+ version => \&version,
+
+ all => \$opt_all,
+ I => \@opt_include,
+ graph => \$opt_graph,
+);
+
+push @opt_include, 'include';
+my %deps = ();
+my %linenos = ();
+
+my @headers = grep { strip($_) } @ARGV;
+
+parse_all(@headers);
+
+if($opt_graph) {
+ graph();
+} else {
+ detect_cycles(@headers);
+}
+
+
+sub help {
+ print "Usage: $0 [options] file...\n";
+ print "\n";
+ print "Options:\n";
+ print " --all\n";
+ print " --graph\n";
+ print "\n";
+ print " -I includedir\n";
+ print "\n";
+ print "To make nice graphs, try:\n";
+ print " $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n";
+ exit;
+}
+
+sub version {
+ print "headerdep version 2\n";
+ exit;
+}
+
+# Get a file name that is relative to our include paths
+sub strip {
+ my $filename = shift;
+
+ for my $i (@opt_include) {
+ my $stripped = $filename;
+ $stripped =~ s/^$i\///;
+
+ return $stripped if $stripped ne $filename;
+ }
+
+ return $filename;
+}
+
+# Search for the file name in the list of include paths
+sub search {
+ my $filename = shift;
+ return $filename if -f $filename;
+
+ for my $i (@opt_include) {
+ my $path = "$i/$filename";
+ return $path if -f $path;
+ }
+
+ return undef;
+}
+
+sub parse_all {
+ # Parse all the headers.
+ my @queue = @_;
+ while(@queue) {
+ my $header = pop @queue;
+ next if exists $deps{$header};
+
+ $deps{$header} = [] unless exists $deps{$header};
+
+ my $path = search($header);
+ next unless $path;
+
+ open(my $file, '<', $path) or die($!);
+ chomp(my @lines = <$file>);
+ close($file);
+
+ for my $i (0 .. $#lines) {
+ my $line = $lines[$i];
+ if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) {
+ push @queue, $dep;
+ push @{$deps{$header}}, [$i + 1, $dep];
+ }
+ }
+ }
+}
+
+sub print_cycle {
+ # $cycle[n] includes $cycle[n + 1];
+ # $cycle[-1] will be the culprit
+ my $cycle = shift;
+
+ # Adjust the line numbers
+ for my $i (0 .. $#$cycle - 1) {
+ $cycle->[$i]->[0] = $cycle->[$i + 1]->[0];
+ }
+ $cycle->[-1]->[0] = 0;
+
+ my $first = shift @$cycle;
+ my $last = pop @$cycle;
+
+ my $msg = "In file included";
+ printf "%s from %s,\n", $msg, $last->[1] if defined $last;
+
+ for my $header (reverse @$cycle) {
+ printf "%s from %s:%d%s\n",
+ " " x length $msg,
+ $header->[1], $header->[0],
+ $header->[1] eq $last->[1] ? ' <-- here' : '';
+ }
+
+ printf "%s:%d: warning: recursive header inclusion\n",
+ $first->[1], $first->[0];
+}
+
+# Find and print the smallest cycle starting in the specified node.
+sub detect_cycles {
+ my @queue = map { [[0, $_]] } @_;
+ while(@queue) {
+ my $top = pop @queue;
+ my $name = $top->[-1]->[1];
+
+ for my $dep (@{$deps{$name}}) {
+ my $chain = [@$top, [$dep->[0], $dep->[1]]];
+
+ # If the dep already exists in the chain, we have a
+ # cycle...
+ if(grep { $_->[1] eq $dep->[1] } @$top) {
+ print_cycle($chain);
+ next if $opt_all;
+ return;
+ }
+
+ push @queue, $chain;
+ }
+ }
+}
+
+sub mangle {
+ $_ = shift;
+ s/\//__/g;
+ s/\./_/g;
+ s/-/_/g;
+ $_;
+}
+
+# Output dependency graph in GraphViz language.
+sub graph {
+ print "digraph {\n";
+
+ print "\t/* vertices */\n";
+ for my $header (keys %deps) {
+ printf "\t%s [label=\"%s\"];\n",
+ mangle($header), $header;
+ }
+
+ print "\n";
+
+ print "\t/* edges */\n";
+ for my $header (keys %deps) {
+ for my $dep (@{$deps{$header}}) {
+ printf "\t%s -> %s;\n",
+ mangle($header), mangle($dep->[1]);
+ }
+ }
+
+ print "}\n";
+}
--
1.5.6.5
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