Re: [PATCH v2 05/15] virtio_blk: drop config_enable

[Cornelia Huck]

On Mon, 6 Oct 2014 18:10:58 +0300
"Michael S. Tsirkin"  wrote:

> Now that virtio core ensures config changes don't
> arrive during probing, drop config_enable flag
> in virtio blk.
> On removal, flush is now sufficient to guarantee that
> no change work is queued.
> 
> This help simplify the driver, and will allow
> setting DRIVER_OK earlier without losing config
> change notifications.
> 
> Signed-off-by: Michael S. Tsirkin 
> ---
>  drivers/block/virtio_blk.c | 23 ---
>  1 file changed, 4 insertions(+), 19 deletions(-)

Reviewed-by: Cornelia Huck 

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[PATCH v2 05/15] virtio_blk: drop config_enable

[Michael S. Tsirkin]

Now that virtio core ensures config changes don't
arrive during probing, drop config_enable flag
in virtio blk.
On removal, flush is now sufficient to guarantee that
no change work is queued.

This help simplify the driver, and will allow
setting DRIVER_OK earlier without losing config
change notifications.

Signed-off-by: Michael S. Tsirkin 
---
 drivers/block/virtio_blk.c | 23 ---
 1 file changed, 4 insertions(+), 19 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 0a58140..91272f1a 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -44,9 +44,6 @@ struct virtio_blk
/* Lock for config space updates */
struct mutex config_lock;
 
-   /* enable config space updates */
-   bool config_enable;
-
/* What host tells us, plus 2 for header & tailer. */
unsigned int sg_elems;
 
@@ -348,8 +345,6 @@ static void virtblk_config_changed_work(struct work_struct 
*work)
u64 capacity, size;
 
mutex_lock(&vblk->config_lock);
-   if (!vblk->config_enable)
-   goto done;
 
/* Host must always specify the capacity. */
virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
@@ -374,7 +369,7 @@ static void virtblk_config_changed_work(struct work_struct 
*work)
set_capacity(vblk->disk, capacity);
revalidate_disk(vblk->disk);
kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
-done:
+
mutex_unlock(&vblk->config_lock);
 }
 
@@ -609,7 +604,6 @@ static int virtblk_probe(struct virtio_device *vdev)
mutex_init(&vblk->config_lock);
 
INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
-   vblk->config_enable = true;
 
err = init_vq(vblk);
if (err)
@@ -771,10 +765,8 @@ static void virtblk_remove(struct virtio_device *vdev)
int index = vblk->index;
int refc;
 
-   /* Prevent config work handler from accessing the device. */
-   mutex_lock(&vblk->config_lock);
-   vblk->config_enable = false;
-   mutex_unlock(&vblk->config_lock);
+   /* Make sure no work handler is accessing the device. */
+   flush_work(&vblk->config_work);
 
del_gendisk(vblk->disk);
blk_cleanup_queue(vblk->disk->queue);
@@ -784,8 +776,6 @@ static void virtblk_remove(struct virtio_device *vdev)
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
 
-   flush_work(&vblk->config_work);
-
refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
put_disk(vblk->disk);
vdev->config->del_vqs(vdev);
@@ -805,11 +795,7 @@ static int virtblk_freeze(struct virtio_device *vdev)
/* Ensure we don't receive any more interrupts */
vdev->config->reset(vdev);
 
-   /* Prevent config work handler from accessing the device. */
-   mutex_lock(&vblk->config_lock);
-   vblk->config_enable = false;
-   mutex_unlock(&vblk->config_lock);
-
+   /* Make sure no work handler is accessing the device. */
flush_work(&vblk->config_work);
 
blk_mq_stop_hw_queues(vblk->disk->queue);
@@ -823,7 +809,6 @@ static int virtblk_restore(struct virtio_device *vdev)
struct virtio_blk *vblk = vdev->priv;
int ret;
 
-   vblk->config_enable = true;
ret = init_vq(vdev->priv);
if (!ret)
blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
-- 
MST

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