Re: [PATCH net-next RFC 1/2] vhost: introduce vhost_has_work()

[Jason Wang]

On 10/22/2015 04:38 PM, Michael S. Tsirkin wrote:
> On Thu, Oct 22, 2015 at 01:27:28AM -0400, Jason Wang wrote:
>> > This path introduces a helper which can give a hint for whether or not
>> > there's a work queued in the work list.
>> > 
>> > Signed-off-by: Jason Wang 
>> > ---
>> >  drivers/vhost/vhost.c | 6 ++
>> >  drivers/vhost/vhost.h | 1 +
>> >  2 files changed, 7 insertions(+)
>> > 
>> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>> > index eec2f11..d42d11e 100644
>> > --- a/drivers/vhost/vhost.c
>> > +++ b/drivers/vhost/vhost.c
>> > @@ -245,6 +245,12 @@ void vhost_work_queue(struct vhost_dev *dev, struct 
>> > vhost_work *work)
>> >  }
>> >  EXPORT_SYMBOL_GPL(vhost_work_queue);
>> >  
>> > +bool vhost_has_work(struct vhost_dev *dev)
>> > +{
>> > +  return !list_empty(&dev->work_list);
>> > +}
>> > +EXPORT_SYMBOL_GPL(vhost_has_work);
>> > +
>> >  void vhost_poll_queue(struct vhost_poll *poll)
>> >  {
>> >vhost_work_queue(poll->dev, &poll->work);
> This doesn't take a lock so it's unreliable.
> I think it's ok in this case since it's just
> an optimization - but pls document this.
>

Ok, will do.
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Re: [PATCH net-next RFC 1/2] vhost: introduce vhost_has_work()

[Michael S. Tsirkin]

On Thu, Oct 22, 2015 at 01:27:28AM -0400, Jason Wang wrote:
> This path introduces a helper which can give a hint for whether or not
> there's a work queued in the work list.
> 
> Signed-off-by: Jason Wang 
> ---
>  drivers/vhost/vhost.c | 6 ++
>  drivers/vhost/vhost.h | 1 +
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index eec2f11..d42d11e 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -245,6 +245,12 @@ void vhost_work_queue(struct vhost_dev *dev, struct 
> vhost_work *work)
>  }
>  EXPORT_SYMBOL_GPL(vhost_work_queue);
>  
> +bool vhost_has_work(struct vhost_dev *dev)
> +{
> + return !list_empty(&dev->work_list);
> +}
> +EXPORT_SYMBOL_GPL(vhost_has_work);
> +
>  void vhost_poll_queue(struct vhost_poll *poll)
>  {
>   vhost_work_queue(poll->dev, &poll->work);


This doesn't take a lock so it's unreliable.
I think it's ok in this case since it's just
an optimization - but pls document this.

> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 4772862..ea0327d 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -37,6 +37,7 @@ struct vhost_poll {
>  
>  void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
>  void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
> +bool vhost_has_work(struct vhost_dev *dev);
>  
>  void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
>unsigned long mask, struct vhost_dev *dev);
> -- 
> 1.8.3.1
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[PATCH net-next RFC 1/2] vhost: introduce vhost_has_work()

[Jason Wang]

This path introduces a helper which can give a hint for whether or not
there's a work queued in the work list.

Signed-off-by: Jason Wang 
---
 drivers/vhost/vhost.c | 6 ++
 drivers/vhost/vhost.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index eec2f11..d42d11e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -245,6 +245,12 @@ void vhost_work_queue(struct vhost_dev *dev, struct 
vhost_work *work)
 }
 EXPORT_SYMBOL_GPL(vhost_work_queue);
 
+bool vhost_has_work(struct vhost_dev *dev)
+{
+   return !list_empty(&dev->work_list);
+}
+EXPORT_SYMBOL_GPL(vhost_has_work);
+
 void vhost_poll_queue(struct vhost_poll *poll)
 {
vhost_work_queue(poll->dev, &poll->work);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 4772862..ea0327d 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -37,6 +37,7 @@ struct vhost_poll {
 
 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
+bool vhost_has_work(struct vhost_dev *dev);
 
 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 unsigned long mask, struct vhost_dev *dev);
-- 
1.8.3.1

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