RE: [Xen-devel] [PATCH resend] xen-netback: switch to threaded irq for control ring

[Paul Durrant]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
> Juergen Gross
> Sent: 22 September 2016 10:03
> To: xen-devel@xxxxxxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Cc: Juergen Gross <jgross@xxxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>
> Subject: [Xen-devel] [PATCH resend] xen-netback: switch to threaded irq for
> control ring
> 
> Instead of open coding it use the threaded irq mechanism in xen-netback.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

How have you tested this change?

  Paul

> ---
> resend due to missing netdev list in first attempt
> ---
>  drivers/net/xen-netback/common.h    |  4 +---
>  drivers/net/xen-netback/interface.c | 38 ++++++-------------------------------
>  drivers/net/xen-netback/netback.c   | 18 ++++--------------
>  3 files changed, 11 insertions(+), 49 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-
> netback/common.h
> index 84d6cbd..b38fb2c 100644
> --- a/drivers/net/xen-netback/common.h
> +++ b/drivers/net/xen-netback/common.h
> @@ -292,8 +292,6 @@ struct xenvif {
>  #endif
> 
>  	struct xen_netif_ctrl_back_ring ctrl;
> -	struct task_struct *ctrl_task;
> -	wait_queue_head_t ctrl_wq;
>  	unsigned int ctrl_irq;
> 
>  	/* Miscellaneous private stuff. */
> @@ -359,7 +357,7 @@ void xenvif_kick_thread(struct xenvif_queue
> *queue);
> 
>  int xenvif_dealloc_kthread(void *data);
> 
> -int xenvif_ctrl_kthread(void *data);
> +irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data);
> 
>  void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff
> *skb);
> 
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-
> netback/interface.c
> index 83deeeb..fb50c6d 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -128,15 +128,6 @@ irqreturn_t xenvif_interrupt(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
> 
> -irqreturn_t xenvif_ctrl_interrupt(int irq, void *dev_id) -{
> -	struct xenvif *vif = dev_id;
> -
> -	wake_up(&vif->ctrl_wq);
> -
> -	return IRQ_HANDLED;
> -}
> -
>  int xenvif_queue_stopped(struct xenvif_queue *queue)  {
>  	struct net_device *dev = queue->vif->dev; @@ -570,8 +561,7 @@
> int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
>  	struct net_device *dev = vif->dev;
>  	void *addr;
>  	struct xen_netif_ctrl_sring *shared;
> -	struct task_struct *task;
> -	int err = -ENOMEM;
> +	int err;
> 
>  	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
>  				     &ring_ref, 1, &addr);
> @@ -581,11 +571,7 @@ int xenvif_connect_ctrl(struct xenvif *vif,
> grant_ref_t ring_ref,
>  	shared = (struct xen_netif_ctrl_sring *)addr;
>  	BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE);
> 
> -	init_waitqueue_head(&vif->ctrl_wq);
> -
> -	err = bind_interdomain_evtchn_to_irqhandler(vif->domid, evtchn,
> -						    xenvif_ctrl_interrupt,
> -						    0, dev->name, vif);
> +	err = bind_interdomain_evtchn_to_irq(vif->domid, evtchn);
>  	if (err < 0)
>  		goto err_unmap;
> 
> @@ -593,19 +579,13 @@ int xenvif_connect_ctrl(struct xenvif *vif,
> grant_ref_t ring_ref,
> 
>  	xenvif_init_hash(vif);
> 
> -	task = kthread_create(xenvif_ctrl_kthread, (void *)vif,
> -			      "%s-control", dev->name);
> -	if (IS_ERR(task)) {
> -		pr_warn("Could not allocate kthread for %s\n", dev->name);
> -		err = PTR_ERR(task);
> +	err = request_threaded_irq(vif->ctrl_irq, NULL, xenvif_ctrl_irq_fn,
> +				   IRQF_ONESHOT, "xen-netback-ctrl", vif);
> +	if (err) {
> +		pr_warn("Could not setup irq handler for %s\n", dev-
> >name);
>  		goto err_deinit;
>  	}
> 
> -	get_task_struct(task);
> -	vif->ctrl_task = task;
> -
> -	wake_up_process(vif->ctrl_task);
> -
>  	return 0;
> 
>  err_deinit:
> @@ -774,12 +754,6 @@ void xenvif_disconnect_data(struct xenvif *vif)
> 
>  void xenvif_disconnect_ctrl(struct xenvif *vif)  {
> -	if (vif->ctrl_task) {
> -		kthread_stop(vif->ctrl_task);
> -		put_task_struct(vif->ctrl_task);
> -		vif->ctrl_task = NULL;
> -	}
> -
>  	if (vif->ctrl_irq) {
>  		xenvif_deinit_hash(vif);
>  		unbind_from_irqhandler(vif->ctrl_irq, vif); diff --git
> a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
> index edbae0b..3d0c989 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -2359,24 +2359,14 @@ static bool xenvif_ctrl_work_todo(struct xenvif
> *vif)
>  	return 0;
>  }
> 
> -int xenvif_ctrl_kthread(void *data)
> +irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data)
>  {
>  	struct xenvif *vif = data;
> 
> -	for (;;) {
> -		wait_event_interruptible(vif->ctrl_wq,
> -					 xenvif_ctrl_work_todo(vif) ||
> -					 kthread_should_stop());
> -		if (kthread_should_stop())
> -			break;
> +	while (xenvif_ctrl_work_todo(vif))
> +		xenvif_ctrl_action(vif);
> 
> -		while (xenvif_ctrl_work_todo(vif))
> -			xenvif_ctrl_action(vif);
> -
> -		cond_resched();
> -	}
> -
> -	return 0;
> +	return IRQ_HANDLED;
>  }
> 
>  static int __init netback_init(void)
> --
> 2.6.6
> 
> 
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