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Subject[PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
Date
IS_ERR(), IS_ERR_OR_NULL(), IS_ERR_VALUE() and WARN*() already contain
unlikely() optimization internally. Thus, there is no point in calling
these functions and defines under likely()/unlikely().

This check is based on the coccinelle rule developed by Enrico Weigelt
https://lore.kernel.org/lkml/1559767582-11081-1-git-send-email-info@metux.net/

Signed-off-by: Denis Efremov <efremov@linux.com>
Cc: Joe Perches <joe@perches.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Whitcroft <apw@canonical.com>
---
scripts/checkpatch.pl | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 93a7edfe0f05..56969ce06df4 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6480,6 +6480,12 @@ sub process {
"Using $1 should generally have parentheses around the comparison\n" . $herecurr);
}

+# nested likely/unlikely calls
+ if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) {
+ WARN("LIKELY_MISUSE",
+ "nested (un)?likely() calls, $1 already uses unlikely() internally\n" . $herecurr);
+ }
+
# whine mightly about in_atomic
if ($line =~ /\bin_atomic\s*\(/) {
if ($realfile =~ m@^drivers/@) {
--
2.21.0
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