checkpatch.pl

			if (defined $cond) {
				substr($s, 0, length($cond), '');
			}
			if ($s =~ /^\s*;/ &&
			    $function_name ne 'uninitialized_var')
			{
				WARN("AVOID_EXTERNS",
				     "externs should be avoided in .c files\n" .  $herecurr);
			}

			if ($paren_space =~ /\n/) {
				WARN("FUNCTION_ARGUMENTS",
				     "arguments for function declarations should follow identifier\n" . $herecurr);
			}

		} elsif ($realfile =~ /\.c$/ && defined $stat &&
		    $stat =~ /^.\s*extern\s+/)
		{
			WARN("AVOID_EXTERNS",
			     "externs should be avoided in .c files\n" .  $herecurr);
		}

# checks for new __setup's
		if ($rawline =~ /\b__setup\("([^"]*)"/) {
			my $name = $1;

			if (!grep(/$name/, @setup_docs)) {
				CHK("UNDOCUMENTED_SETUP",
				    "__setup appears un-documented -- check Documentation/kernel-parameters.txt\n" . $herecurr);
			}
		}

# check for pointless casting of kmalloc return
		if ($line =~ /\*\s*\)\s*[kv][czm]alloc(_node){0,1}\b/) {
			WARN("UNNECESSARY_CASTS",
			     "unnecessary cast may hide bugs, see http://c-faq.com/malloc/mallocnocast.html\n" . $herecurr);
		}

# alloc style
# p = alloc(sizeof(struct foo), ...) should be p = alloc(sizeof(*p), ...)
		if ($^V && $^V ge 5.10.0 &&
		    $line =~ /\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*([kv][mz]alloc(?:_node)?)\s*\(\s*(sizeof\s*\(\s*struct\s+$Lval\s*\))/) {
			CHK("ALLOC_SIZEOF_STRUCT",
			    "Prefer $3(sizeof(*$1)...) over $3($4...)\n" . $herecurr);
		}

# check for krealloc arg reuse
		if ($^V && $^V ge 5.10.0 &&
		    $line =~ /\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*krealloc\s*\(\s*\1\s*,/) {
			WARN("KREALLOC_ARG_REUSE",
			     "Reusing the krealloc arg is almost always a bug\n" . $herecurr);
		}

# check for alloc argument mismatch
		if ($line =~ /\b(kcalloc|kmalloc_array)\s*\(\s*sizeof\b/) {
			WARN("ALLOC_ARRAY_ARGS",
			     "$1 uses number as first arg, sizeof is generally wrong\n" . $herecurr);
		}

# check for multiple semicolons
		if ($line =~ /;\s*;\s*$/) {
			if (WARN("ONE_SEMICOLON",
				 "Statements terminations use 1 semicolon\n" . $herecurr) &&
			    $fix) {
				$fixed[$linenr - 1] =~ s/(\s*;\s*){2,}$/;/g;
			}
		}

# check for switch/default statements without a break;
		if ($^V && $^V ge 5.10.0 &&
		    defined $stat &&
		    $stat =~ /^\+[$;\s]*(?:case[$;\s]+\w+[$;\s]*:[$;\s]*|)*[$;\s]*\bdefault[$;\s]*:[$;\s]*;/g) {
			my $ctx = '';
			my $herectx = $here . "\n";
			my $cnt = statement_rawlines($stat);
			for (my $n = 0; $n < $cnt; $n++) {
				$herectx .= raw_line($linenr, $n) . "\n";
			}
			WARN("DEFAULT_NO_BREAK",
			     "switch default: should use break\n" . $herectx);
		}

# check for gcc specific __FUNCTION__
		if ($line =~ /\b__FUNCTION__\b/) {
			if (WARN("USE_FUNC",
				 "__func__ should be used instead of gcc specific __FUNCTION__\n"  . $herecurr) &&
			    $fix) {
				$fixed[$linenr - 1] =~ s/\b__FUNCTION__\b/__func__/g;
			}
		}

# check for use of yield()
		if ($line =~ /\byield\s*\(\s*\)/) {
			WARN("YIELD",
			     "Using yield() is generally wrong. See yield() kernel-doc (sched/core.c)\n"  . $herecurr);
		}

# check for comparisons against true and false
		if ($line =~ /\+\s*(.*?)\b(true|false|$Lval)\s*(==|\!=)\s*(true|false|$Lval)\b(.*)$/i) {
			my $lead = $1;
			my $arg = $2;
			my $test = $3;
			my $otype = $4;
			my $trail = $5;
			my $op = "!";

			($arg, $otype) = ($otype, $arg) if ($arg =~ /^(?:true|false)$/i);

			my $type = lc($otype);
			if ($type =~ /^(?:true|false)$/) {
				if (("$test" eq "==" && "$type" eq "true") ||
				    ("$test" eq "!=" && "$type" eq "false")) {
					$op = "";
				}

				CHK("BOOL_COMPARISON",
				    "Using comparison to $otype is error prone\n" . $herecurr);

## maybe suggesting a correct construct would better
##				    "Using comparison to $otype is error prone.  Perhaps use '${lead}${op}${arg}${trail}'\n" . $herecurr);

			}
		}

# check for semaphores initialized locked
		if ($line =~ /^.\s*sema_init.+,\W?0\W?\)/) {
			WARN("CONSIDER_COMPLETION",
			     "consider using a completion\n" . $herecurr);
		}

# recommend kstrto* over simple_strto* and strict_strto*
		if ($line =~ /\b((simple|strict)_(strto(l|ll|ul|ull)))\s*\(/) {
			WARN("CONSIDER_KSTRTO",
			     "$1 is obsolete, use k$3 instead\n" . $herecurr);
		}

# check for __initcall(), use device_initcall() explicitly please
		if ($line =~ /^.\s*__initcall\s*\(/) {
			WARN("USE_DEVICE_INITCALL",
			     "please use device_initcall() instead of __initcall()\n" . $herecurr);
		}

# check for various ops structs, ensure they are const.
		my $struct_ops = qr{acpi_dock_ops|
				address_space_operations|
				backlight_ops|
				block_device_operations|
				dentry_operations|
				dev_pm_ops|
				dma_map_ops|
				extent_io_ops|
				file_lock_operations|
				file_operations|
				hv_ops|
				ide_dma_ops|
				intel_dvo_dev_ops|
				item_operations|
				iwl_ops|
				kgdb_arch|
				kgdb_io|
				kset_uevent_ops|
				lock_manager_operations|
				microcode_ops|
				mtrr_ops|
				neigh_ops|
				nlmsvc_binding|
				pci_raw_ops|
				pipe_buf_operations|
				platform_hibernation_ops|
				platform_suspend_ops|
				proto_ops|
				rpc_pipe_ops|
				seq_operations|
				snd_ac97_build_ops|
				soc_pcmcia_socket_ops|
				stacktrace_ops|
				sysfs_ops|
				tty_operations|
				usb_mon_operations|
				wd_ops}x;
		if ($line !~ /\bconst\b/ &&
		    $line =~ /\bstruct\s+($struct_ops)\b/) {
			WARN("CONST_STRUCT",
			     "struct $1 should normally be const\n" .
				$herecurr);
		}

# use of NR_CPUS is usually wrong
# ignore definitions of NR_CPUS and usage to define arrays as likely right
		if ($line =~ /\bNR_CPUS\b/ &&
		    $line !~ /^.\s*\s*#\s*if\b.*\bNR_CPUS\b/ &&
		    $line !~ /^.\s*\s*#\s*define\b.*\bNR_CPUS\b/ &&
		    $line !~ /^.\s*$Declare\s.*\[[^\]]*NR_CPUS[^\]]*\]/ &&
		    $line !~ /\[[^\]]*\.\.\.[^\]]*NR_CPUS[^\]]*\]/ &&
		    $line !~ /\[[^\]]*NR_CPUS[^\]]*\.\.\.[^\]]*\]/)
		{
			WARN("NR_CPUS",
			     "usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc\n" . $herecurr);
		}

# Use of __ARCH_HAS_<FOO> or ARCH_HAVE_<BAR> is wrong.
		if ($line =~ /\+\s*#\s*define\s+((?:__)?ARCH_(?:HAS|HAVE)\w*)\b/) {
			ERROR("DEFINE_ARCH_HAS",
			      "#define of '$1' is wrong - use Kconfig variables or standard guards instead\n" . $herecurr);
		}

# check for %L{u,d,i} in strings
		my $string;
		while ($line =~ /(?:^|")([X\t]*)(?:"|$)/g) {
			$string = substr($rawline, $-[1], $+[1] - $-[1]);
			$string =~ s/%%/__/g;
			if ($string =~ /(?<!%)%L[udi]/) {
				WARN("PRINTF_L",
				     "\%Ld/%Lu are not-standard C, use %lld/%llu\n" . $herecurr);
				last;
			}
		}

# whine mightly about in_atomic
		if ($line =~ /\bin_atomic\s*\(/) {
			if ($realfile =~ m@^drivers/@) {
				ERROR("IN_ATOMIC",
				      "do not use in_atomic in drivers\n" . $herecurr);
			} elsif ($realfile !~ m@^kernel/@) {
				WARN("IN_ATOMIC",
				     "use of in_atomic() is incorrect outside core kernel code\n" . $herecurr);
			}
		}

# check for lockdep_set_novalidate_class
		if ($line =~ /^.\s*lockdep_set_novalidate_class\s*\(/ ||
		    $line =~ /__lockdep_no_validate__\s*\)/ ) {
			if ($realfile !~ m@^kernel/lockdep@ &&
			    $realfile !~ m@^include/linux/lockdep@ &&
			    $realfile !~ m@^drivers/base/core@) {
				ERROR("LOCKDEP",
				      "lockdep_no_validate class is reserved for device->mutex.\n" . $herecurr);
			}
		}

		if ($line =~ /debugfs_create_file.*S_IWUGO/ ||
		    $line =~ /DEVICE_ATTR.*S_IWUGO/ ) {
			WARN("EXPORTED_WORLD_WRITABLE",
			     "Exporting world writable files is usually an error. Consider more restrictive permissions.\n" . $herecurr);
		}
	}

	# If we have no input at all, then there is nothing to report on
	# so just keep quiet.
	if ($#rawlines == -1) {
		exit(0);
	}

	# In mailback mode only produce a report in the negative, for
	# things that appear to be patches.
	if ($mailback && ($clean == 1 || !$is_patch)) {
		exit(0);
	}

	# This is not a patch, and we are are in 'no-patch' mode so
	# just keep quiet.
	if (!$chk_patch && !$is_patch) {
		exit(0);
	}

	if (!$is_patch) {
		ERROR("NOT_UNIFIED_DIFF",
		      "Does not appear to be a unified-diff format patch\n");
	}
	if ($is_patch && $chk_signoff && $signoff == 0) {
		ERROR("MISSING_SIGN_OFF",
		      "Missing Signed-off-by: line(s)\n");
	}

	print report_dump();
	if ($summary && !($clean == 1 && $quiet == 1)) {
		print "$filename " if ($summary_file);
		print "total: $cnt_error errors, $cnt_warn warnings, " .
			(($check)? "$cnt_chk checks, " : "") .
			"$cnt_lines lines checked\n";
		print "\n" if ($quiet == 0);
	}

	if ($quiet == 0) {

		if ($^V lt 5.10.0) {
			print("NOTE: perl $^V is not modern enough to detect all possible issues.\n");
			print("An upgrade to at least perl v5.10.0 is suggested.\n\n");
		}

		# If there were whitespace errors which cleanpatch can fix
		# then suggest that.
		if ($rpt_cleaners) {
			print "NOTE: whitespace errors detected, you may wish to use scripts/cleanpatch or\n";
			print "      scripts/cleanfile\n\n";
			$rpt_cleaners = 0;
		}
	}

	hash_show_words(\%use_type, "Used");
	hash_show_words(\%ignore_type, "Ignored");

	if ($clean == 0 && $fix && "@rawlines" ne "@fixed") {
		my $newfile = $filename . ".EXPERIMENTAL-checkpatch-fixes";
		my $linecount = 0;
		my $f;

		open($f, '>', $newfile)
		    or die "$P: Can't open $newfile for write\n";
		foreach my $fixed_line (@fixed) {
			$linecount++;
			if ($file) {
				if ($linecount > 3) {
					$fixed_line =~ s/^\+//;
					print $f $fixed_line. "\n";
				}
			} else {
				print $f $fixed_line . "\n";
			}
		}
		close($f);

		if (!$quiet) {
			print << "EOM";
Wrote EXPERIMENTAL --fix correction(s) to '$newfile'

Do _NOT_ trust the results written to this file.
Do _NOT_ submit these changes without inspecting them for correctness.

This EXPERIMENTAL file is simply a convenience to help rewrite patches.
No warranties, expressed or implied...

EOM
		}
	}

	if ($clean == 1 && $quiet == 0) {
		print "$vname has no obvious style problems and is ready for submission.\n"
	}
	if ($clean == 0 && $quiet == 0) {
		print << "EOM";
$vname has style problems, please review.

If any of these errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
EOM
	}

	return $clean;
}