From: Lars Ellenberg <lars.ellenb...@linbit.com>
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.reis...@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenb...@linbit.com>
---
drivers/block/drbd/drbd_int.h | 11 +++++++++++
drivers/block/drbd/drbd_worker.c | 8 ++++----
2 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index c88d6c6..a71f8bb 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1778,6 +1778,17 @@ drbd_queue_work(struct drbd_work_queue *q, struct
drbd_work *w)
}
static inline void
+drbd_queue_work_if_unqueued(struct drbd_work_queue *q, struct drbd_work *w)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&q->q_lock, flags);
+ if (list_empty_careful(&w->list))
+ list_add_tail(&w->list, &q->q);
+ spin_unlock_irqrestore(&q->q_lock, flags);
+ wake_up(&q->q_wait);
+}
+
+static inline void
drbd_device_post_work(struct drbd_device *device, int work_bit)
{
if (!test_and_set_bit(work_bit, &device->flags)) {
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 9f0acb0..49b8873 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -452,9 +452,9 @@ void resync_timer_fn(unsigned long data)
{
struct drbd_device *device = (struct drbd_device *) data;
- if (list_empty(&device->resync_work.list))
-
drbd_queue_work(&first_peer_device(device)->connection->sender_work,
- &device->resync_work);
+ drbd_queue_work_if_unqueued(
+ &first_peer_device(device)->connection->sender_work,
+ &device->resync_work);
}
static void fifo_set(struct fifo_buffer *fb, int value)
@@ -1968,7 +1968,7 @@ static void do_unqueued_work(struct drbd_connection
*connection)
static bool dequeue_work_batch(struct drbd_work_queue *queue, struct list_head
*work_list)
{
spin_lock_irq(&queue->q_lock);
- list_splice_init(&queue->q, work_list);
+ list_splice_tail_init(&queue->q, work_list);
spin_unlock_irq(&queue->q_lock);
return !list_empty(work_list);
}
--
1.9.1
--
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