>> This reminds me; do we have a utility to reference wmesg strings back
>> to the code that sets them, a la TAGS? Would this be useful?
> No, and yes respectively.
Okay, I've got an early version written. It's got some fairly
substantial TODO's, and needs a fair bit of cleanup. I would
appreciate any comments anybody has.
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#! /usr/bin/perl -w
# Copyright (c) 1999 Joel Ray Holveck. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $Id$
# NAME
# wtags - generate wchan tag file
#
# SYNOPSIS
# wtags [-cegw] [-v] [path]
#
# DESCRIPTION
# wtags scans a 4.4BSD kernel source tree and creates a database
# listing all the wchan's which are explicitly specified to
# tsleep(9) or similar functions. This is useful for identifying
# where in the kernel a process may be hung.
#
# The source tree to be searched may be specified with path, or
# the current directory is used. Subdirectories are always
# scanned, and symbolic links are always followed.
#
# The options are as follows:
#
# -c Generate ctags(1)-compatible output. Output is appended
# to the file "tags" in the current directory. This file
# is typically used with vi(1).
#
# -e Generate etags(1)-compatible output. Output is appended
# to the file "TAGS" in the current directory. This file
# is typically used with Emacs(1).
#
# -g Generate gtags(1)-compatible output. Output is appended
# to the file "GSYMS" in the current directory. This file
# is typically used with the global(1) tags system by
# Shigio Yamaguchi, which may be used with vi(1), Emacs(1),
# or other systems.
#
# -w Generate a native file format (described below). This
# format is designed to be easily read by humans or machines,
# but no utilities currently use it. -w is the default if
# no other output format is specified.
#
# -v Generate warnings for many cases when a possible call to
# tsleep(9) or a related function is found, but a wchan
# could not be isolated. There are normally many of these
# in correct code; one version of wtags produced 83 such
# diagnostics on the 4.4BSD-Lite kernel. See DIAGNOSTICS,
# below.
#
# wtags will only recognize string literals for wchan arguments.
# A function (such as lf_setlock) which uses a string constant
# instead, or one (such as ttread) which uses one of a few known
# possibilities selected via :? or another mechanism, may have a
# comment such as /* WCHAN: lockf */ on the line in question.
# wtags will then use the indicated channel, and ignore any tsleep
# call on that line.
#
# FILES
# /sys Traditional kernel source location
# WTAGS Default output file, used with -w or if no other
# tag file is specified
# TAGS Emacs(1) tags output file, used with -e
# tags vi(1) tags file, used with -c
# GSYMS global(1) tags file, used with -g
#
# DIAGNOSTICS
# If the -v option is specified, then whenever tsleep (or another
# function that uses wchan) is written in the source file, but no
# wchan can be found, a diagnostic is printed. These diagnostics
# do not always properly describe the issue.
#
# There is one exception to this: if the item appears to be a
# reference to tsleep from within a comment (using a heuristic),
# then no diagnostic is printed.
#
# SEE ALSO
# ps(1), etags(1), ctags(1), global(1), tsleep(9), glimpse(1)
#
# NOTES
# wtags was designed under FreeBSD. Any contributions to allow it
# to work with other OS's would be appreciated.
#
# wtags is written for Perl 5. It may break under other versions
# of Perl.
#
# HISTORY
# wtags was originally written on 22 February, 1999 for FreeBSD 4.0 by
# Joel Ray Holveck <jo...@gnu.org>.
#
# BUGS
# -e and -g are not yet implemented. Notes on the respective file
# formats are in the source.
#
# Presently, only calls to tsleep, asleep, ttysleep, and lockinit are
# scanned. A list of other calls to be scanned is in the source.
#
# Mentions of tsleep in strings are not skipped, and will normally
# generate a diagnostic (if -v is specified).
# TODO:
#
# 0. Fix multiline functionality. Try scanning /sys/kern/subr_log.c for
# an example.
#
# 1. Add etags(1) support. Since I use Emacs so often, this was my original
# goal. I will describe the file format for Emacs's TAGS here:
# Each file is listed separately. At the beginning of the file's entries
# is a formfeed, newline, the complete filename, and the number of bytes
# until the next entry, all terminated by a newline. Example:
# ^L
# /usr/local/src/emacs-20.3/src/alloca.c,785
# The bytecount is from after the newline to before the next formfeed
# (or EOF). Each item in the file is on a separate line. If the tag has
# a name, then the line contains the search string, a del (\177), the
# tag name, a ^A (\001), the line number, a comma, and the byte number.
# This means that we will probably be using something along the lines of:
# tsleep^?wait^A1132,29901
# This will make Emacs search for "tsleep" when the match is used.
# (If the item has no name, then the name and the ^A are elided.)
#
# 2. Add gtags(1) support. Specifically, these should be added to GSYMS.
# I still need to do more research on the GSYMS file format. It seems
# that each record includes the name of the tag, the filename, and a
# comma-separated list of line numbers where the tag appears. If a tag
# appears in more than one file, then more than one entry is created.
#
# 3. Add support for more sleep calls. I need to change out of
# hardcoded regexps first. As of FreeBSD 4.0-CURRENT (24 Feb 1999),
# the calls in question include usbd_bulk_transfer (from
# /sys/dev/usb/usbdi_util.c), waitforit (from /sys/i386/isa/matcd/matcd.c),
# wdsleep (from /sys/i386/isa/wd.c and /sys/pc98/pc98/wd.c), wtwait
# (from /sys/i386/isa/wt.c), BPF_SLEEP (from /sys/net/bpf.c), and
# vm_page_sleep and vm_page_asleep (both from /sys/vm/vm_page.c).
use strict;
use Getopt::Std;
use vars qw($opt_w $opt_c $opt_v);
# A hash indexing wchan strings to a list of locations. The location
# format currently is filename\tlineno, but this may change (probably
# to append ",byteno") when etags support is added.
# Current example:
# "slock"-> [ "/sys/kern/kern_lock.c\t557" ]
# future example:
# "slock"-> [ "/sys/kern/kern_lock.c\t557,14263" ]
# it is also likely that etags support will use a completely different
# system.
my %wchan;
# a hash indexing location strings to the function name being used (eg,
# "kern_lock.c\t557"->"tsleep")
my %sleepcall;
# a hash relating sleep calls to the argument offset of the
# wchan string
# FIXME The regexes that scan for these calls should be built
# from this.
my %wchanarg;
$wchanarg{"tsleep"}=2;
$wchanarg{"asleep"}=2;
$wchanarg{"ttysleep"}=3;
$wchanarg{"lockinit"}=2;
# $prog_label is prefixed on all warnings and error messages. to
# comply with standards, it should be "wtags: ", but leaving it empty
# allows you to use emacs's compile-mode with its output to check the
# source of each warning message against the offending kernel source.
# my $prog_label = "wtags: ";
my $prog_label = "";
sub scanfile {
my ($file) = @_;
open FILE, $file or warn "$prog_label$file: can't open: $!; skipped\n";
while (<FILE>) {
# FIXME Isn't recognized on subsequent lines
m,/\*\s*WCHAN:\s*([A-Za-z0-9]+)\s*\*/, && goto EXPLICIT_WCHAN;
/\b(tsleep|asleep|ttysleep|lockinit)(.*)/ || next;
my $looks_like_comment;
my $sleepcall = $1; # Saved to add to %sleepcall
my $rest = $2;
# This matches either /* or a line starting with a * (for
# boxed comments).
# FIXME This doesn't work for calls within calls.
$looks_like_comment = ((m,^\s*/?\*,) ? 1 : 0);
$_ = $rest;
GOT_SLEEP:
# We keep the current arg number in $arg. If we are in a
# comment, then set $incomment to 1. parens is the current
# parens level. Inside the tsleep call's parens is level 0.
my ($curarg, $incomment, $parens, $lines_scanned) = (0, 0, -1, 0);
while ($curarg < $wchanarg{$sleepcall}) {
# Handle this first so it can next; to itself.
if ($incomment) {
if (m,\*/(.*),) {
$_ = $1;
$incomment = 0;
} else {
if (++$lines_scanned >= 5) {
$opt_v and warn "$prog_label$file: $.: tsleep call over
five lines; skipped\n";
goto PARSE_FAILED;
}
$_ = <FILE>;
if (!defined $_) {
$opt_v and warn "$prog_label$file: $.: early EOF hit;
continuing";
goto PARSE_FAILED;
}
next;
}
}
# Parse out the following: /*, */, (, ), ',', and 'tsleep'.
# FIXME Doesn't exclude tokens within strings
if
(m:.*?(/\*|\*/|\(|\)|,|\btsleep|\basleep|\bttysleep|\blockinit)(.*)$:) {
if ($1 eq "/*") {
$incomment = $1;
} elsif ($1 eq "*/") {
# End of comment hit
goto PARSE_FAILED;
} elsif ($1 eq "(") {
++$parens;
} elsif ($1 eq ")") {
$parens--;
if ($parens < 0) {
# Suppress the warning if there is a comment
# that includes a reference to tsleep just
# like this one does.
if (!($looks_like_comment && $curarg == 0)) {
$opt_v and warn "$prog_label$file: $.: tsleep call
with too few args; skipped\n";
}
goto PARSE_FAILED;
}
} elsif ($1 eq ",") {
$parens == 0 and $curarg++;
} elsif ($1 eq "*/") {
# There was a reference to tsleep within a comment.
goto PARSE_FAILED;
} else { # new tsleep call
$opt_v and warn "$prog_label$file: $.: tsleep called within
tsleep\n";
$sleepcall = $1;
$_ = $2;
goto GOT_SLEEP;
}
$_ = $2;
} else {
# This is taken out because it probably is not useful.
# if ($parens == -1) {
# # This was probably a reference to tsleep, rather than
# # a call.
# goto PARSE_FAILED;
# }
$_ = <FILE>; # get the next line
if (!defined $_) {
$opt_v and warn "$prog_label$file: $.: early EOF hit;
continuing";
goto PARSE_FAILED;
}
$looks_like_comment = ((m,^\s*/?\*,) ? 1 : 0); # mostly for
switching to the next tsleep call
if (++$lines_scanned >= 5) {
# This is probably a sign of a misparse, or incomplete code
# (say, in an #if 0 or something).
$opt_v and warn "$prog_label$file: $.: tsleep call over
five lines; skipped\n";
goto PARSE_FAILED;
}
}
}
# We are now looking at the correct argument.
# FIXME Handle looking at a comment
while (/^\s*$/) {
# End of line was after the comma; skip blank lines.
$_ = <FILE>;
if (!defined $_) {
$opt_v and warn "$prog_label$file: $.: early EOF hit;
continuing";
goto PARSE_FAILED;
}
}
if (! m,^\s*"([^\042]*)",) { # Use octal to keep quotes matched for
emacs
$opt_v and warn "$prog_label$file: $.: wmesg is not a string
literal; skipped\n";
goto PARSE_FAILED;
}
EXPLICIT_WCHAN:
my $wmesg = $1;
if (defined $wchan{$wmesg}) {
push @{ $wchan{$wmesg} }, ("$file\t$.");
} else {
$wchan{$wmesg} = [ "$file\t$." ];
}
$sleepcall{$wmesg} = $sleepcall;
PARSE_FAILED:
}
close FILE;
}
sub scandir {
my ($wd, $glob) = @_;
my $file;
my @flist;
print "==> $wd\n";
@flist = glob("$wd/$glob");
defined @flist or warn "${prog_label}can't scan $wd: $!; skipped\n";
foreach $file (@flist) {
if (-d $file) {
scandir($file,$glob);
} else {
$file =~ /.c$/ and scanfile($file);
}
}
}
getopts('cvw');
$opt_c or $opt_w = 1; # -w is the default output format
$opt_w and (open WTAGS, ">WTAGS" or die "${prog_label}can't create WTAGS:$!\n");
$opt_c and (open CTAGS, ">>tags" or die "${prog_label}can't append to
tags:$!\n");
# Use the output of `pwd` as the directory if nothing was specified on the
# command line.
my $wd = ((defined $ARGV[0])?$ARGV[0]:`pwd`);
$wd =~ s,/?\n?$,,; # Strip off any terminating slash and/or newline
scandir($wd, "*");
# FIXME This loop should be built and eval'd.
foreach my $wchan (sort keys %wchan) {
$opt_w && print WTAGS "\f\n$wchan\n";
foreach my $spot (@{ $wchan{$wchan} }) {
# Should I use a regex for ctags instead?
$opt_c && print CTAGS "$wchan\t$spot\n";
$opt_w && print WTAGS "$spot\n";
}
}
close CTAGS;
close WTAGS;
__END__
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--
Joel Ray Holveck - jo...@gnu.org
Fourth law of programming:
Anything that can go wrong wi
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