From cb426e99ff9225e94fb56bd4c5cfcce8b78a3904 Mon Sep 17 00:00:00 2001 From: Joe Perches Date: Thu, 25 Jun 2015 15:02:46 -0700 Subject: [PATCH] checkpatch: check for uncommented waitqueue_active() Linus sayeth: : Pretty much every single time people use this "if : (waitqueue_active())" model, it tends to be a bug, because it means : that there is zero serialization with people who are just about to go : to sleep. It's fundamentally racy against all the "wait_event()" loops : that carefully do memory barriers between testing conditions and going : to sleep, because the memory barriers now don't exist on the waking : side. : : So I'm making a new rule: if you use waitqueue_active(), I want an : explanation for why it's not racy with the waiter. A big comment about : the memory ordering, or about higher-level locks that are held by the : caller, or something. Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- scripts/checkpatch.pl | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index c5ec977b9c37..3f2ff26c631c 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -4898,6 +4898,13 @@ sub process { "memory barrier without comment\n" . $herecurr); } } +# check for waitqueue_active without a comment. + if ($line =~ /\bwaitqueue_active\s*\(/) { + if (!ctx_has_comment($first_line, $linenr)) { + WARN("WAITQUEUE_ACTIVE", + "waitqueue_active without comment\n" . $herecurr); + } + } # check of hardware specific defines if ($line =~ m@^.\s*\#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@ && $realfile !~ m@include/asm-@) { CHK("ARCH_DEFINES", -- 2.20.1