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

[Juergen Gross <jgross@xxxxxxxx>]

Instead of open coding it use the threaded irq mechanism in
xen-netback.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
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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