linux-kernel - [PATCH] checkpatch: types found in one source file do not affect processing of others

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Date:	Mon, 18 May 2015 15:33:29 +0200
From:	Alex Dowad <alexinbeijing@...il.com>
To:	Andy Whitcroft <apw@...onical.com>, Joe Perches <joe@...ches.com>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] checkpatch: types found in one source file do not affect processing of others

checkpatch uses various cues in its input files to discover the names of
user-defined types. It then uses that information when processing expressions,
to discover more style issues.

Unfortunately, in rare cases, this means that checkpatch may give different
results if you run it on several files at the same time, or one by one! The
reason is that it may identify a type (or something that looks like a type)
in one file, and then carry this information over when processing a different
file.

As an example, drivers/staging/media/bcm2048/radio-bcm2048.c contains this
line (in a macro):

  size value;

Then drivers/staging/media/davinci_vpfe/vpfe_video.c has this line:

  while (size * *nbuffers > vpfe_dev->video_limit)

If checkpatch processes these 2 files together, the (spurious) "size" type
detected in the first file will cause it to flag the second file for
improper use of the pointer dereference operator!

Therefore, keep user-defined types in a separate array from built-in ones,
and reset the array of user-defined types at the beginning of each new
source file.

Signed-off-by: Alex Dowad <alexinbeijing@...il.com>
---

Dear patch checkers,

I am not a Perl programmer -- please let me know if there is a better way to
accomplish what I am trying to do here.

Your feedback will be appreciated,
Alex Dowad

 scripts/checkpatch.pl | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 89b1df4..5a5668f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -424,6 +424,10 @@ our @typeListWithAttr = (
 	qr{union\s+$InitAttribute\s+$Ident},
 );

+# includes user-defined types discovered in the code
+# reset at the beginning of each source file
+our @allTypeList = (@typeList);
+
 our @modifierList = (
 	qr{fastcall},
 );
@@ -511,7 +515,7 @@ $misspellings = join("|", sort keys %spelling_fix) if keys %spelling_fix;

 sub build_types {
 	my $mods = "(?x:  \n" . join("|\n  ", @modifierList) . "\n)";
-	my $all = "(?x:  \n" . join("|\n  ", @typeList) . "\n)";
+	my $all = "(?x:  \n" . join("|\n  ", @allTypeList) . "\n)";
 	my $Misordered = "(?x:  \n" . join("|\n  ", @typeListMisordered) . "\n)";
 	my $allWithAttr = "(?x:  \n" . join("|\n  ", @typeListWithAttr) . "\n)";
 	$Modifier	= qr{(?:$Attribute|$Sparse|$mods)};
@@ -745,6 +749,7 @@ for my $filename (@ARGV) {
 	@fixed = ();
 	@fixed_inserted = ();
 	@fixed_deleted = ();
+	@allTypeList = (@typeList);
 	$fixlinenr = -1;
 }

@@ -1616,7 +1621,7 @@ sub possible {

 		} else {
 			warn "POSSIBLE: $possible ($line)\n" if ($dbg_possible);
-			push(@typeList, $possible);
+			push(@allTypeList, $possible);
 		}
 		build_types();
 	} else {
-- 
2.0.0.GIT

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