From 15e26f6a3c6de2c665b4a30b9a70a902111f281f Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Mon, 28 Apr 2014 11:43:21 +0200 Subject: [PATCH] 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 Signed-off-by: Lars Ellenberg --- 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 c88d6c6be70b..a71f8bb9dc80 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -1777,6 +1777,17 @@ drbd_queue_work(struct drbd_work_queue *q, struct drbd_work *w) wake_up(&q->q_wait); } +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) { diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c index 9f0acb011f30..49b88731b349 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); } -- 2.34.1