Re: [PATCH 1/1] update balloon size in balloon "probe"

2016-09-23 Thread Michael S. Tsirkin
On Fri, Sep 23, 2016 at 04:47:57PM +0300, Denis V. Lunev wrote:
> From: Konstantin Neumoin 
> 
> Patch
> Commit 3d2a3774c1b046f548ebea0391a602fd5685a307
> Author: Michael S. Tsirkin 
> Date:   Tue Mar 10 11:55:08 2015 +1030
> virtio-balloon: do not call blocking ops when !TASK_RUNNING
> has added a regression. Original code with wait_event_interruptible
> checked the condition before start waiting and started balloon operations
> if necessary.

I don't get it, sorry.

+   add_wait_queue(>config_change, );
+   for (;;) {
+   if ((diff = towards_target(vb)) != 0 ||
+   vb->need_stats_update ||
+   kthread_should_stop() ||
+   freezing(current))
+   break;
+   wait_woken(, TASK_INTERRUPTIBLE, 
MAX_SCHEDULE_TIMEOUT);
+   }
+   remove_wait_queue(>config_change, );

Seems to check the condition before waiting.

The issue is more likely with this patch:

commit fad7b7b27b6a168ca8ebc84482043886f837b89d
Author: Petr Mladek 
Date:   Mon Jan 25 17:38:05 2016 +0100

virtio_balloon: Use a workqueue instead of "vballoon" kthread



> Right now balloon is not inflated if ballon target is set before the
> driver is loaded.
> 
> Signed-off-by: Konstantin Neumoin 
> Signed-off-by: Denis V. Lunev 
> CC: "Michael S. Tsirkin" 
> ---
>  drivers/virtio/virtio_balloon.c | 4 
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 4e7003d..0a6c10f 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -577,6 +577,10 @@ static int virtballoon_probe(struct virtio_device *vdev)
>  
>   virtio_device_ready(vdev);
>  
> + if (towards_target(vb))
> + virtballoon_changed(vdev);
> + update_balloon_size(vb);
> +
>   return 0;
>  
>  out_del_vqs:


I know we have same thing on restore, but it seems bogus
there as well:
if (towards_target(vb))
virtballoon_changed(vdev);
update_balloon_size(vb);

makes no sense because virtballoon_changed merely queues
the work.


> -- 
> 2.7.4
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[PATCH 1/1] update balloon size in balloon "probe"

2016-09-23 Thread Denis V. Lunev
From: Konstantin Neumoin 

Patch
Commit 3d2a3774c1b046f548ebea0391a602fd5685a307
Author: Michael S. Tsirkin 
Date:   Tue Mar 10 11:55:08 2015 +1030
virtio-balloon: do not call blocking ops when !TASK_RUNNING
has added a regression. Original code with wait_event_interruptible
checked the condition before start waiting and started balloon operations
if necessary.

Right now balloon is not inflated if ballon target is set before the
driver is loaded.

Signed-off-by: Konstantin Neumoin 
Signed-off-by: Denis V. Lunev 
CC: "Michael S. Tsirkin" 
---
 drivers/virtio/virtio_balloon.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 4e7003d..0a6c10f 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -577,6 +577,10 @@ static int virtballoon_probe(struct virtio_device *vdev)
 
virtio_device_ready(vdev);
 
+   if (towards_target(vb))
+   virtballoon_changed(vdev);
+   update_balloon_size(vb);
+
return 0;
 
 out_del_vqs:
-- 
2.7.4

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