Commit cb426e99 authored Jun 25, 2015 by Joe Perches Committed by Linus Torvalds Jun 25, 2015

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 <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent cbdc2810

scripts/checkpatch.pl

+7 −0

Original line number	Diff line number	Diff line
		@@ -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\#\sif.*\b(__i386__\|__powerpc64__\|__sun__\|__s390x__)\b@ && $realfile !~ m@include/asm-@) {
		CHK("ARCH_DEFINES",