diff options
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 108 |
1 files changed, 51 insertions, 57 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 0c3691f..2c9a92f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -22,8 +22,7 @@ #include <linux/virtio.h> #include <linux/virtio_balloon.h> #include <linux/swap.h> -#include <linux/kthread.h> -#include <linux/freezer.h> +#include <linux/workqueue.h> #include <linux/delay.h> #include <linux/slab.h> #include <linux/module.h> @@ -49,11 +48,12 @@ struct virtio_balloon { struct virtio_device *vdev; struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; - /* Where the ballooning thread waits for config to change. */ - wait_queue_head_t config_change; + /* The balloon servicing is delegated to a freezable workqueue. */ + struct work_struct work; - /* The thread servicing the balloon. */ - struct task_struct *thread; + /* Prevent updating balloon when it is being canceled. */ + spinlock_t stop_update_lock; + bool stop_update; /* Waiting for host to ack the pages we released. */ wait_queue_head_t acked; @@ -135,9 +135,10 @@ static void set_page_pfns(u32 pfns[], struct page *page) pfns[i] = page_to_balloon_pfn(page) + i; } -static void fill_balloon(struct virtio_balloon *vb, size_t num) +static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) { struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; + unsigned num_allocated_pages; /* We can only do one array worth at a time. */ num = min(num, ARRAY_SIZE(vb->pfns)); @@ -162,10 +163,13 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num) adjust_managed_page_count(page, -1); } + num_allocated_pages = vb->num_pfns; /* Did we get any? */ if (vb->num_pfns != 0) tell_host(vb, vb->inflate_vq); mutex_unlock(&vb->balloon_lock); + + return num_allocated_pages; } static void release_pages_balloon(struct virtio_balloon *vb) @@ -251,14 +255,19 @@ static void update_balloon_stats(struct virtio_balloon *vb) * with a single buffer. From that point forward, all conversations consist of * a hypervisor request (a call to this function) which directs us to refill * the virtqueue with a fresh stats buffer. Since stats collection can sleep, - * we notify our kthread which does the actual work via stats_handle_request(). + * we delegate the job to a freezable workqueue that will do the actual work via + * stats_handle_request(). */ static void stats_request(struct virtqueue *vq) { struct virtio_balloon *vb = vq->vdev->priv; vb->need_stats_update = 1; - wake_up(&vb->config_change); + + spin_lock(&vb->stop_update_lock); + if (!vb->stop_update) + queue_work(system_freezable_wq, &vb->work); + spin_unlock(&vb->stop_update_lock); } static void stats_handle_request(struct virtio_balloon *vb) @@ -281,8 +290,12 @@ static void stats_handle_request(struct virtio_balloon *vb) static void virtballoon_changed(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; + unsigned long flags; - wake_up(&vb->config_change); + spin_lock_irqsave(&vb->stop_update_lock, flags); + if (!vb->stop_update) + queue_work(system_freezable_wq, &vb->work); + spin_unlock_irqrestore(&vb->stop_update_lock, flags); } static inline s64 towards_target(struct virtio_balloon *vb) @@ -345,43 +358,25 @@ static int virtballoon_oom_notify(struct notifier_block *self, return NOTIFY_OK; } -static int balloon(void *_vballoon) +static void balloon(struct work_struct *work) { - struct virtio_balloon *vb = _vballoon; - DEFINE_WAIT_FUNC(wait, woken_wake_function); - - set_freezable(); - while (!kthread_should_stop()) { - s64 diff; - - try_to_freeze(); - - add_wait_queue(&vb->config_change, &wait); - for (;;) { - if ((diff = towards_target(vb)) != 0 || - vb->need_stats_update || - kthread_should_stop() || - freezing(current)) - break; - wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); - } - remove_wait_queue(&vb->config_change, &wait); + struct virtio_balloon *vb; + s64 diff; - if (vb->need_stats_update) - stats_handle_request(vb); - if (diff > 0) - fill_balloon(vb, diff); - else if (diff < 0) - leak_balloon(vb, -diff); - update_balloon_size(vb); + vb = container_of(work, struct virtio_balloon, work); + diff = towards_target(vb); - /* - * For large balloon changes, we could spend a lot of time - * and always have work to do. Be nice if preempt disabled. - */ - cond_resched(); - } - return 0; + if (vb->need_stats_update) + stats_handle_request(vb); + + if (diff > 0) + diff -= fill_balloon(vb, diff); + else if (diff < 0) + diff += leak_balloon(vb, -diff); + update_balloon_size(vb); + + if (diff) + queue_work(system_freezable_wq, work); } static int init_vqs(struct virtio_balloon *vb) @@ -499,9 +494,11 @@ static int virtballoon_probe(struct virtio_device *vdev) goto out; } + INIT_WORK(&vb->work, balloon); + spin_lock_init(&vb->stop_update_lock); + vb->stop_update = false; vb->num_pages = 0; mutex_init(&vb->balloon_lock); - init_waitqueue_head(&vb->config_change); init_waitqueue_head(&vb->acked); vb->vdev = vdev; vb->need_stats_update = 0; @@ -523,16 +520,8 @@ static int virtballoon_probe(struct virtio_device *vdev) virtio_device_ready(vdev); - vb->thread = kthread_run(balloon, vb, "vballoon"); - if (IS_ERR(vb->thread)) { - err = PTR_ERR(vb->thread); - goto out_del_vqs; - } - return 0; -out_del_vqs: - unregister_oom_notifier(&vb->nb); out_oom_notify: vdev->config->del_vqs(vdev); out_free_vb: @@ -559,7 +548,12 @@ static void virtballoon_remove(struct virtio_device *vdev) struct virtio_balloon *vb = vdev->priv; unregister_oom_notifier(&vb->nb); - kthread_stop(vb->thread); + + spin_lock_irq(&vb->stop_update_lock); + vb->stop_update = true; + spin_unlock_irq(&vb->stop_update_lock); + cancel_work_sync(&vb->work); + remove_common(vb); kfree(vb); } @@ -570,10 +564,9 @@ static int virtballoon_freeze(struct virtio_device *vdev) struct virtio_balloon *vb = vdev->priv; /* - * The kthread is already frozen by the PM core before this + * The workqueue is already frozen by the PM core before this * function is called. */ - remove_common(vb); return 0; } @@ -589,7 +582,8 @@ static int virtballoon_restore(struct virtio_device *vdev) virtio_device_ready(vdev); - fill_balloon(vb, towards_target(vb)); + if (towards_target(vb)) + virtballoon_changed(vdev); update_balloon_size(vb); return 0; } |
