I ran a report to extract export-symbol usage by kernel modules. The results
are at http://www.sudhaa.com/~ram/misc/export_report.txt
The report lists:
1. All the exported symbols and their usage counts by in-kernel modules.
2. for each in-kernel module, lists the modules and the exported symbols
from those modules, that it depends on.
Highlights:
On x86 architecture
(1) 880 exported symbols not used by any in-kernel modules.
(2) 1792 exported symbols used only once.
I hope this report/tool shall help all inkernel modules to revisit their usage
of kernel interfaces.
This patch integrates the report-generator into the kernel build process. After
applying this patch, invoke 'make export_report' and it creates the report in
Documentation/export_report.txt
Signed-off-by Ram Pai ([email protected])
Makefile | 12 ++++
scripts/Makefile.modpost | 7 ++
scripts/export_report.pl | 135 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 154 insertions(+)
Index: 2617rc1/scripts/Makefile.modpost
===================================================================
--- 2617rc1.orig/scripts/Makefile.modpost 2006-04-12 17:20:35.000000000 -0700
+++ 2617rc1/scripts/Makefile.modpost 2006-04-12 17:21:11.000000000 -0700
@@ -60,9 +60,16 @@
$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
$(filter-out FORCE,$^)
+quiet_cmd_importfile = IMPORT_EXTRACT
+ cmd_importfile = perl $(objtree)/scripts/export_report.pl \
+ -k $(kernelsymfile) \
+ -o $(objtree)/Documentation/export_report.txt \
+ $(patsubst %.o,%.mod.c,$(filter-out vmlinux FORCE, $^))
+
PHONY += __modpost
__modpost: $(wildcard vmlinux) $(modules:.ko=.o) FORCE
$(call cmd,modpost)
+ $(if $(KBUILD_EXPORT_REPORT), $(call cmd,importfile))
# Declare generated files as targets for modpost
$(symverfile): __modpost ;
Index: 2617rc1/scripts/export_report.pl
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2617rc1/scripts/export_report.pl 2006-04-12 17:21:29.000000000 -0700
@@ -0,0 +1,134 @@
+#!/usr/bin/perl
+#
+# (C) Copyright IBM Corporation 2006.
+# Released under GPL v2.
+# Author : Ram Pai ([email protected])
+#
+# Usage: export_report.pl -k Module.symvers [-o report_file ] *.mod.c
+#
+
+use Getopt::Std;
+
+sub numerically {
+ ($sym, $no1) = split / /, $a;
+ ($sym, $no2) = split / /, $b;
+ return $no1 <=> $no2;
+}
+
+sub alphabetically {
+ ($module1, $value1, undef) = split / /, "@{$a}";
+ ($module2, $value2, undef) = split / /, "@{$b}";
+ if ($value1 == $value2) {
+ if ($module1 lt $module2) {
+ return 1;
+ } elsif ($module1 eq $module2) {
+ return 0;
+ }
+ return -1;
+ }
+ return $value1 <=> $value2;
+}
+
+sub print_depends_on {
+ my ($href) = @_;
+ print "\n";
+ while (($mod, $list) = each %$href) {
+ print "\t$mod:\n";
+ foreach $sym (sort numerically @{$list}) {
+ ($symbol, $no) = split / /, $sym;
+ printf("\t\t%-25s\t%-25d\n", $symbol, $no);
+ }
+ print "\n";
+ }
+ print "\n";
+ print "~"x80 , "\n";
+}
+
+sub usage {
+ die "Usage: @_ -h -k Module.symvers [ -o outputfile ] \n";
+}
+
+
+if (not getopts('hk:o:') or defined $opt_h or not defined $opt_k) {
+ usage($0);
+}
+
+unless (open(MODULE_SYMVERS, $opt_k)) {
+ die "Sorry, cannot open $opt_k: $!\n";
+}
+
+if (defined $opt_o) {
+ unless (open(OUTPUT_HANDLE, ">$opt_o")) {
+ die "Sorry, cannot open $opt_o: $!\n";
+ }
+ select OUTPUT_HANDLE;
+}
+
+#
+# collect all the symbols and their attributes from the
+# Module.symvers file
+#
+while ( <MODULE_SYMVERS> ) {
+ chomp;
+ ($crc, $symbol, $module, $gpl) = split;
+ $SYMBOL { $symbol } = [ $module , "0" , $symbol, $gpl];
+}
+close(MODULE_SYMVERS);
+
+#
+# collect the usage count of each symbol.
+#
+for ($i = 0; $i <= $#ARGV; $i++) {
+ $thismod = $ARGV[$i];
+ unless (open(MODULE_MODULE, $thismod)) {
+ print "Sorry, cannot open $kernel: $!\n";
+ next;
+ }
+ while ( <MODULE_MODULE> ) {
+ chomp;
+ if ( $_ !~ /0x[0-9a-f]{7,8},/ ) {
+ next;
+ }
+ (undef, undef, undef, undef, $symbol) = split /([,"])/, $_;
+ ($module, $value, $symbol, $gpl) = @{$SYMBOL{$symbol}};
+ $SYMBOL{ $symbol } = [ $module , $value+1 , $symbol, $gpl];
+ push(@{$MODULE{$thismod}} , $symbol);
+ }
+ close(MODULE_MODULE);
+}
+
+
+print "\tTHIS FILE REPORTS THE USAGE PATTERNS OF EXPORTED SYMBOLS BY IN_TREE\n";
+print "\t\t\t\tMODULES\n";
+printf("%s\n\n\n","x"x80);
+printf("\t\t\t\INDEX\n\n\n");
+printf("SECTION 1: USAGE COUNTS OF ALL EXPORTED SYMBOLS\n");
+printf("SECTION 2: LIST OF MODULES AND THE EXPORTED SYMBOLS THEY USE\n");
+printf("%s\n\n\n","x"x80);
+printf("SECTION 1:\tTHE EXPORTED SYMBOLS AND THEIR USAGE COUNT\n\n");
+printf("%-25s\t%-25s\t%-5s\t%-25s\n", "SYMBOL", "MODULE", "USAGE COUNT", "EXPORT TYPE");
+#
+# print the list of unused exported symbols
+#
+foreach $list (sort alphabetically values(%SYMBOL)) {
+ ($module, $value, $symbol, $gpl) = split / /, "@{$list}";
+ printf("%-25s\t%-25s\t%-10s\t%-25s\n", $symbol, $module, $value, $gpl);
+}
+printf("%s\n\n\n","x"x80);
+
+
+printf("SECTION 2:\n\tThis section reports export-symbol-usage of in-kernel
+modules. Each module lists all the modules, and the symbols from the module it
+depends on. Each listed symbol reports the number of modules using that
+symbols.\n");
+
+print "~"x80 , "\n";
+while (($thismod, $list) = each %MODULE) {
+ undef %depends;
+ print "\t\t\t$thismod\n";
+ foreach $symbol (@{$list}) {
+ ($module, $value, undef, $gpl) = @{$SYMBOL{$symbol}};
+ push (@{$depends{"$module"}}, "$symbol $value");
+ }
+ print_depends_on(\%depends);
+}
Index: 2617rc1/Makefile
===================================================================
--- 2617rc1.orig/Makefile 2006-04-12 17:20:35.000000000 -0700
+++ 2617rc1/Makefile 2006-04-12 17:21:11.000000000 -0700
@@ -363,7 +363,7 @@
# Detect when mixed targets is specified, and make a second invocation
# of make so .config is not included in this case either (for *config).
-no-dot-config-targets := clean mrproper distclean \
+no-dot-config-targets := clean mrproper distclean export_report\
cscope TAGS tags help %docs check%
config-targets := 0
@@ -433,6 +433,16 @@
core-y := usr/
endif # KBUILD_EXTMOD
+ifeq ($(MAKECMDGOALS), export_report)
+ KBUILD_EXPORT_REPORT := 1
+ export KBUILD_EXPORT_REPORT
+endif
+
+PHONY += export_report
+export_report: FORCE
+ $(Q)$(MAKE) allmodconfig
+ $(Q)$(MAKE) vmlinux modules
+
ifeq ($(dot-config),1)
# In this section, we need .config
@@ -1029,6 +1039,8 @@
@echo ' cscope - Generate cscope index'
@echo ' kernelrelease - Output the release version string'
@echo ' kernelversion - Output the version stored in Makefile'
+ @echo ' export_report - Output the export symbol usage '
+ @echo ' in Documentation/export_symbol.txt'
@echo ''
@echo 'Static analysers'
@echo ' checkstack - Generate a list of stack hogs'
-
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