From: Joe Perches <joe@xxxxxxxxxxx>
Subject: checkpatch: warn on self-assignments
The uninitialized_var() macro was removed recently via commit 63a0895d960a
("compiler: Remove uninitialized_var() macro") as it's not a particularly
useful warning and its use can "paper over real bugs".
Add a checkpatch test to warn on self-assignments as a means to avoid
compiler warnings and as a back-door mechanism to reproduce the old
uninitialized_var macro behavior.
[akpm@xxxxxxxxxxxxxxxxxxxx: coding style fixes]
Link: https://lkml.kernel.org/r/afc2cffdd315d3e4394af149278df9e8af7f49f4.camel@xxxxxxxxxxx
Signed-off-by: Joe Perches <joe@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Cc: Denis Efremov <efremov@xxxxxxxxx>
Cc: Julia Lawall <julia.lawall@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
scripts/checkpatch.pl | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/scripts/checkpatch.pl~checkpatch-warn-on-self-assignments
+++ a/scripts/checkpatch.pl
@@ -3899,6 +3899,17 @@ sub process {
#ignore lines not being added
next if ($line =~ /^[^\+]/);
+# check for self assignments used to avoid compiler warnings
+# e.g.: int foo = foo, *bar = NULL;
+# struct foo bar = *(&(bar));
+ if ($line =~ /^\+\s*(?:$Declare)?([A-Za-z_][A-Za-z\d_]*)\s*=/) {
+ my $var = $1;
+ if ($line =~ /^\+\s*(?:$Declare)?$var\s*=\s*(?:$var|\*\s*\(?\s*&\s*\(?\s*$var\s*\)?\s*\)?)\s*[;,]/) {
+ WARN("SELF_ASSIGNMENT",
+ "Do not use self-assignments to avoid compiler warnings\n" . $herecurr);
+ }
+ }
+
# check for dereferences that span multiple lines
if ($prevline =~ /^\+.*$Lval\s*(?:\.|->)\s*$/ &&
$line =~ /^\+\s*(?!\#\s*(?!define\s+|if))\s*$Lval/) {
_
