drbd: add drbd_queue_work_if_unqueued helper
We sometimes do
if (list_empty(&w.list))
drbd_queue_work(&q, &w.list);
Removal (list_del_init) may happen outside all locks, after all
pending work entries have been moved to an on-stack local work list.
For not dynamically allocated, but embeded, work structs,
we must avoid to re-add until it really was removed.
Move that list_empty check inside the spin_lock(&q->q_lock)
within the helper function, and change to list_empty_careful().
This may have been the reason for a list_add corruption
inside drbd_queue_work().
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2 files changed