checkpatch: add likely/unlikely comparison misuse test

Add a test for probably likely/unlikely misuses where the comparison is
likely misplaced

	if (likely(foo) > 0)
vs
	if (likely(foo > 0))

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Christoph Jaeger <cj@linux.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 786017d4d057..41223c946808 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5239,6 +5239,13 @@ sub process {
                               "#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/@) {