Re: [PATCH net-next v8 5/7] net: vhost: introduce bitmap for vhost_poll

[Jason Wang <jasowang@redhat.com>]

On 2018年08月19日 20:11, xiangxia.m.yue@gmail.com wrote:
> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>
> The bitmap of vhost_dev can help us to check if the
> specified poll is scheduled. This patch will be used
> for next two patches.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> ---
>   drivers/vhost/net.c   | 11 +++++++++--
>   drivers/vhost/vhost.c | 17 +++++++++++++++--
>   drivers/vhost/vhost.h |  7 ++++++-
>   3 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 1eff72d..23d7ffc 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -1135,8 +1135,15 @@ static int vhost_net_open(struct inode *inode, struct file *f)
>   	}
>   	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
>   
> -	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
> -	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
> +	vhost_poll_init(n->poll + VHOST_NET_VQ_TX,
> +			handle_tx_net,
> +			VHOST_NET_VQ_TX,
> +			EPOLLOUT, dev);
> +
> +	vhost_poll_init(n->poll + VHOST_NET_VQ_RX,
> +			handle_rx_net,
> +			VHOST_NET_VQ_RX,
> +			EPOLLIN, dev);
>   
>   	f->private_data = n;
>   
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index a1c06e7..dc88a60 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -186,7 +186,7 @@ void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
>   
>   /* Init poll structure */
>   void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
> -		     __poll_t mask, struct vhost_dev *dev)
> +		     __u8 poll_id, __poll_t mask, struct vhost_dev *dev)
>   {
>   	init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
>   	init_poll_funcptr(&poll->table, vhost_poll_func);
> @@ -194,6 +194,7 @@ void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
>   	poll->dev = dev;
>   	poll->wqh = NULL;
>   
> +	poll->poll_id = poll_id;
>   	vhost_work_init(&poll->work, fn);
>   }
>   EXPORT_SYMBOL_GPL(vhost_poll_init);
> @@ -276,8 +277,16 @@ bool vhost_has_work(struct vhost_dev *dev)
>   }
>   EXPORT_SYMBOL_GPL(vhost_has_work);
>   
> +bool vhost_has_work_pending(struct vhost_dev *dev, int poll_id)
> +{
> +	return !llist_empty(&dev->work_list) &&
> +		test_bit(poll_id, dev->work_pending);

I think we've already had something similar. E.g can we test 
VHOST_WORK_QUEUED instead?

Thanks

> +}
> +EXPORT_SYMBOL_GPL(vhost_has_work_pending);
> +
>   void vhost_poll_queue(struct vhost_poll *poll)
>   {
> +	set_bit(poll->poll_id, poll->dev->work_pending);
>   	vhost_work_queue(poll->dev, &poll->work);
>   }
>   EXPORT_SYMBOL_GPL(vhost_poll_queue);
> @@ -354,6 +363,7 @@ static int vhost_worker(void *data)
>   		if (!node)
>   			schedule();
>   
> +		bitmap_zero(dev->work_pending, VHOST_DEV_MAX_VQ);
>   		node = llist_reverse_order(node);
>   		/* make sure flag is seen after deletion */
>   		smp_wmb();
> @@ -420,6 +430,8 @@ void vhost_dev_init(struct vhost_dev *dev,
>   	struct vhost_virtqueue *vq;
>   	int i;
>   
> +	BUG_ON(nvqs > VHOST_DEV_MAX_VQ);
> +
>   	dev->vqs = vqs;
>   	dev->nvqs = nvqs;
>   	mutex_init(&dev->mutex);
> @@ -428,6 +440,7 @@ void vhost_dev_init(struct vhost_dev *dev,
>   	dev->iotlb = NULL;
>   	dev->mm = NULL;
>   	dev->worker = NULL;
> +	bitmap_zero(dev->work_pending, VHOST_DEV_MAX_VQ);
>   	init_llist_head(&dev->work_list);
>   	init_waitqueue_head(&dev->wait);
>   	INIT_LIST_HEAD(&dev->read_list);
> @@ -445,7 +458,7 @@ void vhost_dev_init(struct vhost_dev *dev,
>   		vhost_vq_reset(dev, vq);
>   		if (vq->handle_kick)
>   			vhost_poll_init(&vq->poll, vq->handle_kick,
> -					EPOLLIN, dev);
> +					i, EPOLLIN, dev);
>   	}
>   }
>   EXPORT_SYMBOL_GPL(vhost_dev_init);
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 6c844b9..60b6f6d 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -30,6 +30,7 @@ struct vhost_poll {
>   	wait_queue_head_t        *wqh;
>   	wait_queue_entry_t              wait;
>   	struct vhost_work	  work;
> +	__u8			  poll_id;
>   	__poll_t		  mask;
>   	struct vhost_dev	 *dev;
>   };
> @@ -37,9 +38,10 @@ 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);
> +bool vhost_has_work_pending(struct vhost_dev *dev, int poll_id);
>   
>   void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
> -		     __poll_t mask, struct vhost_dev *dev);
> +		     __u8 id, __poll_t mask, struct vhost_dev *dev);
>   int vhost_poll_start(struct vhost_poll *poll, struct file *file);
>   void vhost_poll_stop(struct vhost_poll *poll);
>   void vhost_poll_flush(struct vhost_poll *poll);
> @@ -152,6 +154,8 @@ struct vhost_msg_node {
>     struct list_head node;
>   };
>   
> +#define VHOST_DEV_MAX_VQ	128
> +
>   struct vhost_dev {
>   	struct mm_struct *mm;
>   	struct mutex mutex;
> @@ -159,6 +163,7 @@ struct vhost_dev {
>   	int nvqs;
>   	struct eventfd_ctx *log_ctx;
>   	struct llist_head work_list;
> +	DECLARE_BITMAP(work_pending, VHOST_DEV_MAX_VQ);
>   	struct task_struct *worker;
>   	struct vhost_umem *umem;
>   	struct vhost_umem *iotlb;