[Linux-kernel-mentees] [PATCH RFC 1/2] checkpatch: fix multi-statement macro checks

Dwaipayan Ray dwaipayanray1 at gmail.com
Wed Sep 30 21:03:32 UTC 2020

Checkpatch.pl generates errors which are false positive for
certain multi-statemenent macros.

The specific case investigated was whitespace separated statement
terminated by a semicolon. Checkpatch wrongly classifies such
as a multi-statement macro.

For example, commit 4649079b9de1 ("tracing: Make ftrace packed
events have align of 1") when analyzed with checkpatch generates:

ERROR: Macros with multiple statements should be enclosed in a do -
while loop
+#define __field_packed(type, container, item)    type item;

The error is misleading in this case and should not be produced.
The solution undertaken is to exclude any macro which doesn't
have any non-WSP character after the first and only semicolon(;)
present in it. This shall allow macros of the form "type item;",
"type item[size];", etc. to not generate the multi-statement macro

Signed-off-by: Dwaipayan Ray <dwaipayanray1 at gmail.com>
 scripts/checkpatch.pl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 9e65d21456f1..72c4072307ea 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5346,6 +5346,7 @@ sub process {
 			    $dstat !~ /^for\s*$Constant\s+(?:$Ident|-?$Constant)$/ &&	# for (...) bar()
 			    $dstat !~ /^do\s*{/ &&					# do {...
 			    $dstat !~ /^\(\{/ &&						# ({...
+			    $dstat !~ /^[^;]*;\s*$/ &&				# space separated statement;
 			    $ctx !~ /^.\s*#\s*define\s+TRACE_(?:SYSTEM|INCLUDE_FILE|INCLUDE_PATH)\b/)
 				if ($dstat =~ /^\s*if\b/) {

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