diff options
Diffstat (limited to 'include/linux/swait.h')
| -rw-r--r-- | include/linux/swait.h | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/include/linux/swait.h b/include/linux/swait.h index 84f9745365ff..bf8cb0dee23c 100644 --- a/include/linux/swait.h +++ b/include/linux/swait.h @@ -9,7 +9,19 @@ #include <asm/current.h> /* - * Simple wait queues + * BROKEN wait-queues. + * + * These "simple" wait-queues are broken garbage, and should never be + * used. The comments below claim that they are "similar" to regular + * wait-queues, but the semantics are actually completely different, and + * every single user we have ever had has been buggy (or pointless). + * + * A "swake_up()" only wakes up _one_ waiter, which is not at all what + * "wake_up()" does, and has led to problems. In other cases, it has + * been fine, because there's only ever one waiter (kvm), but in that + * case gthe whole "simple" wait-queue is just pointless to begin with, + * since there is no "queue". Use "wake_up_process()" with a direct + * pointer instead. * * While these are very similar to regular wait queues (wait.h) the most * important difference is that the simple waitqueue allows for deterministic |