checkpatch.pl

# check for k[mz]alloc with multiplies that could be kmalloc_array/kcalloc
		if ($^V && $^V ge 5.10.0 &&
		    defined $stat &&
		    $stat =~ /^\+\s*($Lval)\s*\=\s*(?:$balanced_parens)?\s*(k[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)\s*,/) {
			my $oldfunc = $3;
			my $a1 = $4;
			my $a2 = $10;
			my $newfunc = "kmalloc_array";
			$newfunc = "kcalloc" if ($oldfunc eq "kzalloc");
			my $r1 = $a1;
			my $r2 = $a2;
			if ($a1 =~ /^sizeof\s*\S/) {
				$r1 = $a2;
				$r2 = $a1;
			}
			if ($r1 !~ /^sizeof\b/ && $r2 =~ /^sizeof\s*\S/ &&
			    !($r1 =~ /^$Constant$/ || $r1 =~ /^[A-Z_][A-Z0-9_]*$/)) {
				my $ctx = '';
				my $herectx = $here . "\n";
				my $cnt = statement_rawlines($stat);
				for (my $n = 0; $n < $cnt; $n++) {
					$herectx .= raw_line($linenr, $n) . "\n";
				}
				if (WARN("ALLOC_WITH_MULTIPLY",
					 "Prefer $newfunc over $oldfunc with multiply\n" . $herectx) &&
				    $cnt == 1 &&
				    $fix) {
					$fixed[$fixlinenr] =~ s/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*(k[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)/$1 . ' = ' . "$newfunc(" . trim($r1) . ', ' . trim($r2)/e;
				}
			}
		}

# 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) {
				$fixed[$fixlinenr] =~ s/(\s*;\s*){2,}$/;/g;
			}
		}

# check for #defines like: 1 << <digit> that could be BIT(digit), it is not exported to uapi
		if ($realfile !~ m@^include/uapi/@ &&
		    $line =~ /#\s*define\s+\w+\s+\(?\s*1\s*([ulUL]*)\s*\<\<\s*(?:\d+|$Ident)\s*\)?/) {
			my $ull = "";
			$ull = "_ULL" if (defined($1) && $1 =~ /ll/i);
			if (CHK("BIT_MACRO",
				"Prefer using the BIT$ull macro\n" . $herecurr) &&
			    $fix) {
				$fixed[$fixlinenr] =~ s/\(?\s*1\s*[ulUL]*\s*<<\s*(\d+|$Ident)\s*\)?/BIT${ull}($1)/;
			}
		}

# check for #if defined CONFIG_<FOO> || defined CONFIG_<FOO>_MODULE
		if ($line =~ /^\+\s*#\s*if\s+defined(?:\s*\(?\s*|\s+)(CONFIG_[A-Z_]+)\s*\)?\s*\|\|\s*defined(?:\s*\(?\s*|\s+)\1_MODULE\s*\)?\s*$/) {
			my $config = $1;
			if (WARN("PREFER_IS_ENABLED",
				 "Prefer IS_ENABLED(<FOO>) to CONFIG_<FOO> || CONFIG_<FOO>_MODULE\n" . $herecurr) &&
			    $fix) {
				$fixed[$fixlinenr] = "\+#if IS_ENABLED($config)";
			}
		}

# check for case / default statements not preceded by break/fallthrough/switch
		if ($line =~ /^.\s*(?:case\s+(?:$Ident|$Constant)\s*|default):/) {
			my $has_break = 0;
			my $has_statement = 0;
			my $count = 0;
			my $prevline = $linenr;
			while ($prevline > 1 && ($file || $count < 3) && !$has_break) {
				$prevline--;
				my $rline = $rawlines[$prevline - 1];
				my $fline = $lines[$prevline - 1];
				last if ($fline =~ /^\@\@/);
				next if ($fline =~ /^\-/);
				next if ($fline =~ /^.(?:\s*(?:case\s+(?:$Ident|$Constant)[\s$;]*|default):[\s$;]*)*$/);
				$has_break = 1 if ($rline =~ /fall[\s_-]*(through|thru)/i);
				next if ($fline =~ /^.[\s$;]*$/);
				$has_statement = 1;
				$count++;
				$has_break = 1 if ($fline =~ /\bswitch\b|\b(?:break\s*;[\s$;]*$|return\b|goto\b|continue\b)/);
			}
			if (!$has_break && $has_statement) {
				WARN("MISSING_BREAK",
				     "Possible switch case/default not preceded by break or fallthrough comment\n" . $herecurr);
			}
		}

# 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) {
				$fixed[$fixlinenr] =~ s/\b__FUNCTION__\b/__func__/g;
			}
		}

# check for uses of __DATE__, __TIME__, __TIMESTAMP__
		while ($line =~ /\b(__(?:DATE|TIME|TIMESTAMP)__)\b/g) {
			ERROR("DATE_TIME",
			      "Use of the '$1' macro makes the build non-deterministic\n" . $herecurr);
		}

# 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 or more appropriate function please
		if ($line =~ /^.\s*__initcall\s*\(/) {
			WARN("USE_DEVICE_INITCALL",
			     "please use device_initcall() or more appropriate function instead of __initcall() (see include/linux/init.h)\n" . $herecurr);
		}

# check for various structs that are normally const (ops, kgdb, device_tree)
# and avoid what seem like struct definitions 'struct foo {'
		if ($line !~ /\bconst\b/ &&
		    $line =~ /\bstruct\s+($const_structs)\b(?!\s*\{)/) {
			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);
		}

# likely/unlikely comparisons similar to "(likely(foo) > 0)"
		if ($^V && $^V ge 5.10.0 &&
		    $line =~ /\b((?:un)?likely)\s*\(\s*$FuncArg\s*\)\s*$Compare/) {
			WARN("LIKELY_MISUSE",
			     "Using $1 should generally have parentheses around the comparison\n" . $herecurr);
		}

# 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);
			}
		}

# whine about ACCESS_ONCE
		if ($^V && $^V ge 5.10.0 &&
		    $line =~ /\bACCESS_ONCE\s*$balanced_parens\s*(=(?!=))?\s*($FuncArg)?/) {
			my $par = $1;
			my $eq = $2;
			my $fun = $3;
			$par =~ s/^\(\s*(.*)\s*\)$/$1/;
			if (defined($eq)) {
				if (WARN("PREFER_WRITE_ONCE",
					 "Prefer WRITE_ONCE(<FOO>, <BAR>) over ACCESS_ONCE(<FOO>) = <BAR>\n" . $herecurr) &&
				    $fix) {
					$fixed[$fixlinenr] =~ s/\bACCESS_ONCE\s*\(\s*\Q$par\E\s*\)\s*$eq\s*\Q$fun\E/WRITE_ONCE($par, $fun)/;
				}
			} else {
				if (WARN("PREFER_READ_ONCE",
					 "Prefer READ_ONCE(<FOO>) over ACCESS_ONCE(<FOO>)\n" . $herecurr) &&
				    $fix) {
					$fixed[$fixlinenr] =~ s/\bACCESS_ONCE\s*\(\s*\Q$par\E\s*\)/READ_ONCE($par)/;
				}
			}
		}

# check for mutex_trylock_recursive usage
		if ($line =~ /mutex_trylock_recursive/) {
			ERROR("LOCKING",
			      "recursive locking is bad, do not use this ever.\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 ($line =~ /debugfs_create_\w+.*\b$mode_perms_world_writable\b/ ||
		    $line =~ /DEVICE_ATTR.*\b$mode_perms_world_writable\b/) {
			WARN("EXPORTED_WORLD_WRITABLE",
			     "Exporting world writable files is usually an error. Consider more restrictive permissions.\n" . $herecurr);
		}

# Mode permission misuses where it seems decimal should be octal
# This uses a shortcut match to avoid unnecessary uses of a slow foreach loop
		if ($^V && $^V ge 5.10.0 &&
		    defined $stat &&
		    $line =~ /$mode_perms_search/) {
			foreach my $entry (@mode_permission_funcs) {
				my $func = $entry->[0];
				my $arg_pos = $entry->[1];

				my $lc = $stat =~ tr@\n@@;
				$lc = $lc + $linenr;
				my $stat_real = raw_line($linenr, 0);
				for (my $count = $linenr + 1; $count <= $lc; $count++) {
					$stat_real = $stat_real . "\n" . raw_line($count, 0);
				}

				my $skip_args = "";
				if ($arg_pos > 1) {
					$arg_pos--;
					$skip_args = "(?:\\s*$FuncArg\\s*,\\s*){$arg_pos,$arg_pos}";
				}
				my $test = "\\b$func\\s*\\(${skip_args}($FuncArg(?:\\|\\s*$FuncArg)*)\\s*[,\\)]";
				if ($stat =~ /$test/) {
					my $val = $1;
					$val = $6 if ($skip_args ne "");
					if (($val =~ /^$Int$/ && $val !~ /^$Octal$/) ||
					    ($val =~ /^$Octal$/ && length($val) ne 4)) {
						ERROR("NON_OCTAL_PERMISSIONS",
						      "Use 4 digit octal (0777) not decimal permissions\n" . "$here\n" . $stat_real);
					}
					if ($val =~ /^$Octal$/ && (oct($val) & 02)) {
						ERROR("EXPORTED_WORLD_WRITABLE",
						      "Exporting writable files is usually an error. Consider more restrictive permissions.\n" . "$here\n" . $stat_real);
					}
				}
			}
		}

# check for uses of S_<PERMS> that could be octal for readability
		if ($line =~ /\b$mode_perms_string_search\b/) {
			my $val = "";
			my $oval = "";
			my $to = 0;
			my $curpos = 0;
			my $lastpos = 0;
			while ($line =~ /\b(($mode_perms_string_search)\b(?:\s*\|\s*)?\s*)/g) {
				$curpos = pos($line);
				my $match = $2;
				my $omatch = $1;
				last if ($lastpos > 0 && ($curpos - length($omatch) != $lastpos));
				$lastpos = $curpos;
				$to |= $mode_permission_string_types{$match};
				$val .= '\s*\|\s*' if ($val ne "");
				$val .= $match;
				$oval .= $omatch;
			}
			$oval =~ s/^\s*\|\s*//;
			$oval =~ s/\s*\|\s*$//;
			my $octal = sprintf("%04o", $to);
			if (WARN("SYMBOLIC_PERMS",
				 "Symbolic permissions '$oval' are not preferred. Consider using octal permissions '$octal'.\n" . $herecurr) &&
			    $fix) {
				$fixed[$fixlinenr] =~ s/$val/$octal/;
			}
		}

# validate content of MODULE_LICENSE against list from include/linux/module.h
		if ($line =~ /\bMODULE_LICENSE\s*\(\s*($String)\s*\)/) {
			my $extracted_string = get_quoted_string($line, $rawline);
			my $valid_licenses = qr{
						GPL|
						GPL\ v2|
						GPL\ and\ additional\ rights|
						Dual\ BSD/GPL|
						Dual\ MIT/GPL|
						Dual\ MPL/GPL|
						Proprietary
					}x;
			if ($extracted_string !~ /^"(?:$valid_licenses)"$/x) {
				WARN("MODULE_LICENSE",
				     "unknown module license " . $extracted_string . "\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 && $file !~ /cover-letter\.patch$/) {
		ERROR("NOT_UNIFIED_DIFF",
		      "Does not appear to be a unified-diff format patch\n");
	}
	if ($is_patch && $has_commit_log && $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";
	}

	if ($quiet == 0) {
		# If there were any defects found and not already fixing them
		if (!$clean and !$fix) {
			print << "EOM"

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.
EOM
		}
		# If there were whitespace errors which cleanpatch can fix
		# then suggest that.
		if ($rpt_cleaners) {
			$rpt_cleaners = 0;
			print << "EOM"

NOTE: Whitespace errors detected.
      You may wish to use scripts/cleanpatch or scripts/cleanfile
EOM
		}
	}

	if ($clean == 0 && $fix &&
	    ("@rawlines" ne "@fixed" ||
	     $#fixed_inserted >= 0 || $#fixed_deleted >= 0)) {
		my $newfile = $filename;
		$newfile .= ".EXPERIMENTAL-checkpatch-fixes" if (!$fix_inplace);
		my $linecount = 0;
		my $f;

		@fixed = fix_inserted_deleted_lines(\@fixed, \@fixed_inserted, \@fixed_deleted);

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