[PATCH v4] checkpatch: extend attributes check to handle more patterns

From: Dwaipayan Ray
Date: Sun Oct 25 2020 - 02:53:10 EST


It is generally preferred that the macros from
include/linux/compiler_attributes.h are used, unless there
is a reason not to.

checkpatch currently checks __attribute__ for each of
packed, aligned, printf, scanf, and weak. Other declarations
in compiler_attributes.h are not handled.

Add a generic test to check the presence of such attributes.
Some attributes require more specific handling and are kept
separate.

New attributes which are now handled are:

__alias__(#symbol)
__always_inline__
__assume_aligned__(a, ## __VA_ARGS__)
__cold__
__const__
__copy__(symbol)
__designated_init__
__externally_visible__
__gnu_inline__
__malloc__
__mode__(x)
__no_caller_saved_registers__
__noclone__
__noinline__
__nonstring__
__noreturn__
__pure__
__unused__
__used__

Also add fixes for the generic attributes check.

Link: https://lore.kernel.org/linux-kernel-mentees/3ec15b41754b01666d94b76ce51b9832c2dd577a.camel@xxxxxxxxxxx/
Suggested-by: Joe Perches <joe@xxxxxxxxxxx>
Signed-off-by: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx>
---
scripts/checkpatch.pl | 107 ++++++++++++++++++++++++++++--------------
1 file changed, 71 insertions(+), 36 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 7e505688257a..1b736e9042d2 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6155,50 +6155,85 @@ sub process {
}
}

-# Check for __attribute__ packed, prefer __packed
+# Check for compiler attributes
if ($realfile !~ m@\binclude/uapi/@ &&
- $line =~ /\b__attribute__\s*\(\s*\(.*\bpacked\b/) {
- WARN("PREFER_PACKED",
- "__packed is preferred over __attribute__((packed))\n" . $herecurr);
- }
+ $rawline =~ /\b__attribute__\s*\(\s*($balanced_parens)\s*\)/) {
+ my $attr = $1;
+ $attr =~ s/\s*\(\s*(.*)\)\s*/$1/;
+
+ my %attr_list = (
+ "alias" => "__alias",
+ "aligned" => "__aligned",
+ "always_inline" => "__always_inline",
+ "assume_aligned" => "__assume_aligned",
+ "cold" => "__cold",
+ "const" => "__const",
+ "copy" => "__copy",
+ "designated_init" => "__designated_init",
+ "externally_visible" => "__visible",
+ "gnu_inline" => "__gnu_inline",
+ "malloc" => "__malloc",
+ "mode" => "__mode",
+ "no_caller_saved_registers" => "__no_caller_saved_registers",
+ "noclone" => "__noclone",
+ "noinline" => "noinline",
+ "nonstring" => "__nonstring",
+ "noreturn" => "__noreturn",
+ "packed" => "__packed",
+ "pure" => "__pure",
+ "used" => "__used"
+ );
+
+ if ($attr =~ /^(\w+)\s*(${balanced_parens})?/) {
+ my $curr_attr = $1;
+ my $params = '';
+ $params = $2 if defined($2);
+ $curr_attr =~ s/^[\s_]+|[\s_]+$//g;
+
+ if (exists($attr_list{$curr_attr})) {
+ my $new = $attr_list{$curr_attr};
+ if (WARN("PREFER_DEFINED_ATTRIBUTE_MACRO",
+ "$new$params is preferred over __attribute__(($attr))\n" . $herecurr) &&
+ $fix) {
+ $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*\Q$attr\E\s*\)\s*\)/$new$params/;
+ }
+ }
+ }

-# Check for __attribute__ aligned, prefer __aligned
- if ($realfile !~ m@\binclude/uapi/@ &&
- $line =~ /\b__attribute__\s*\(\s*\(.*aligned/) {
- WARN("PREFER_ALIGNED",
- "__aligned(size) is preferred over __attribute__((aligned(size)))\n" . $herecurr);
- }
+ # Check for __attribute__ format(printf, prefer __printf
+ if ($attr =~ /^_*format_*\s*\(\s*printf/) {
+ if (WARN("PREFER_DEFINED_ATTRIBUTE_MACRO",
+ "__printf(string-index, first-to-check) is preferred over __attribute__((format(printf, string-index, first-to-check)))\n" . $herecurr) &&
+ $fix) {
+ $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*_*format_*\s*\(\s*printf\s*,\s*(.*)\)\s*\)\s*\)/"__printf(" . trim($1) . ")"/ex;

-# Check for __attribute__ section, prefer __section
- if ($realfile !~ m@\binclude/uapi/@ &&
- $line =~ /\b__attribute__\s*\(\s*\(.*_*section_*\s*\(\s*("[^"]*")/) {
- my $old = substr($rawline, $-[1], $+[1] - $-[1]);
- my $new = substr($old, 1, -1);
- if (WARN("PREFER_SECTION",
- "__section($new) is preferred over __attribute__((section($old)))\n" . $herecurr) &&
- $fix) {
- $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*_*section_*\s*\(\s*\Q$old\E\s*\)\s*\)\s*\)/__section($new)/;
+ }
}
- }

-# Check for __attribute__ format(printf, prefer __printf
- if ($realfile !~ m@\binclude/uapi/@ &&
- $line =~ /\b__attribute__\s*\(\s*\(\s*format\s*\(\s*printf/) {
- if (WARN("PREFER_PRINTF",
- "__printf(string-index, first-to-check) is preferred over __attribute__((format(printf, string-index, first-to-check)))\n" . $herecurr) &&
- $fix) {
- $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*format\s*\(\s*printf\s*,\s*(.*)\)\s*\)\s*\)/"__printf(" . trim($1) . ")"/ex;
+ # Check for __attribute__ format(scanf, prefer __scanf
+ if ($attr =~ /^_*format_*\s*\(\s*scanf\b/) {
+ if (WARN("PREFER_DEFINED_ATTRIBUTE_MACRO",
+ "__scanf(string-index, first-to-check) is preferred over __attribute__((format(scanf, string-index, first-to-check)))\n" . $herecurr) &&
+ $fix) {
+ $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*_*format_*\s*\(\s*scanf\s*,\s*(.*)\)\s*\)\s*\)/"__scanf(" . trim($1) . ")"/ex;
+ }
+ }

+ # Check for __attribute__ section, prefer __section
+ if ($attr =~ /^_*section_*\s*\(\s*("[^"]*")/) {
+ my $old = substr($attr, $-[1], $+[1] - $-[1]);
+ my $new = substr($old, 1, -1);
+ if (WARN("PREFER_DEFINED_ATTRIBUTE_MACRO",
+ "__section($new) is preferred over __attribute__((section($old)))\n" . $herecurr) &&
+ $fix) {
+ $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*_*section_*\s*\(\s*\Q$old\E\s*\)\s*\)\s*\)/__section($new)/;
+ }
}
- }

-# Check for __attribute__ format(scanf, prefer __scanf
- if ($realfile !~ m@\binclude/uapi/@ &&
- $line =~ /\b__attribute__\s*\(\s*\(\s*format\s*\(\s*scanf\b/) {
- if (WARN("PREFER_SCANF",
- "__scanf(string-index, first-to-check) is preferred over __attribute__((format(scanf, string-index, first-to-check)))\n" . $herecurr) &&
- $fix) {
- $fixed[$fixlinenr] =~ s/\b__attribute__\s*\(\s*\(\s*format\s*\(\s*scanf\s*,\s*(.*)\)\s*\)\s*\)/"__scanf(" . trim($1) . ")"/ex;
+ # Check for __attribute__ unused, prefer __always_unused or __maybe_unused
+ if ($attr =~ /^_*unused/) {
+ WARN("PREFER_DEFINED_ATTRIBUTE_MACRO",
+ "__always_unused or __maybe_unused is preferred over __attribute__((__unused__))\n" . $herecurr);
}
}

--
2.27.0