Commit cb426e99 authored by Joe Perches's avatar Joe Perches Committed by Linus Torvalds

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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cbdc2810
...@@ -4898,6 +4898,13 @@ sub process { ...@@ -4898,6 +4898,13 @@ sub process {
"memory barrier without comment\n" . $herecurr); "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" . $herecurr);
}
}
# check of hardware specific defines # check of hardware specific defines
if ($line =~ m@^.\s*\#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@ && $realfile !~ m@include/asm-@) { if ($line =~ m@^.\s*\#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@ && $realfile !~ m@include/asm-@) {
CHK("ARCH_DEFINES", CHK("ARCH_DEFINES",
......
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