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 <[email protected]>
---
On Sun, 2015-01-11 at 14:34 -0500, Christoph Jaeger wrote:
> > drivers/platform/goldfish/goldfish_pipe.c:285: if (unlikely(bufflen)
> > == 0)
>
> Well, the conditional statement works as intended. Of course, the branch
> prediction doesn't.
>
> Coccinelle should be able to check for this kind of likely()/unlikely() usage,
> shouldn't it?
Most likely, checkpatch could too, but not as well.
This misuse isn't very common. (2 in current source?)
scripts/checkpatch.pl | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 6afc24b..b8d47dc 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5219,6 +5219,13 @@ 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/@) {
--
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