__wake_up_common() should wake up all non-exclusive waiters and exclusive waiters as many as nr_exclusive, but currently it does not.
Consider a wait queue like the following for example: A(exclusive) -> B(non-exclusive) -> C(non-exclusive) Current code will wake up only A when nr_exclusive = 1, but has to wake up A, B and C. Make it do as we expect. Signed-off-by: Byungchul Park <[email protected]> --- kernel/sched/wait.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c index 9453efe..0ea1083 100644 --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -67,12 +67,23 @@ static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, { wait_queue_t *curr, *next; + /* + * We use nr_exclusive = 0 to wake up all no matter whether + * WQ_FLAG_EXCLUSIVE is set. However, we have to distinguish + * between the case and having finished all exclusive wake-up. + * So make nr_exclusive non-zero in advance in the former case. + */ + nr_exclusive = nr_exclusive ?: -1; + list_for_each_entry_safe(curr, next, &q->task_list, task_list) { unsigned flags = curr->flags; + if ((flags & WQ_FLAG_EXCLUSIVE) && !nr_exclusive) + continue; + if (curr->func(curr, mode, wake_flags, key) && - (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) - break; + (flags & WQ_FLAG_EXCLUSIVE)) + nr_exclusive--; } } -- 1.9.1
