[PATCH 2/2] xen/netback: cleanup init and deinit code

From: Juergen Gross
Date: Mon Oct 14 2019 - 05:09:18 EST


Do some cleanup of the netback init and deinit code:

- add an omnipotent queue deinit function usable from
xenvif_disconnect_data() and the error path of xenvif_connect_data()
- only install the irq handlers after initializing all relevant items
(especially the kthreads related to the queue)
- there is no need to use get_task_struct() after creating a kthread
and using put_task_struct() again after having stopped it.
- use kthread_run() instead of kthread_create() to spare the call of
wake_up_process().

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
drivers/net/xen-netback/interface.c | 114 +++++++++++++++++-------------------
1 file changed, 54 insertions(+), 60 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 103ed00775eb..68dd7bb07ca6 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -626,6 +626,38 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
return err;
}

+static void xenvif_disconnect_queue(struct xenvif_queue *queue)
+{
+ if (queue->tx_irq) {
+ unbind_from_irqhandler(queue->tx_irq, queue);
+ if (queue->tx_irq == queue->rx_irq)
+ queue->rx_irq = 0;
+ queue->tx_irq = 0;
+ }
+
+ if (queue->rx_irq) {
+ unbind_from_irqhandler(queue->rx_irq, queue);
+ queue->rx_irq = 0;
+ }
+
+ if (queue->task) {
+ kthread_stop(queue->task);
+ queue->task = NULL;
+ }
+
+ if (queue->dealloc_task) {
+ kthread_stop(queue->dealloc_task);
+ queue->dealloc_task = NULL;
+ }
+
+ if (queue->napi.poll) {
+ netif_napi_del(&queue->napi);
+ queue->napi.poll = NULL;
+ }
+
+ xenvif_unmap_frontend_data_rings(queue);
+}
+
int xenvif_connect_data(struct xenvif_queue *queue,
unsigned long tx_ring_ref,
unsigned long rx_ring_ref,
@@ -651,13 +683,27 @@ int xenvif_connect_data(struct xenvif_queue *queue,
netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll,
XENVIF_NAPI_WEIGHT);

+ queue->stalled = true;
+
+ task = kthread_run(xenvif_kthread_guest_rx, queue,
+ "%s-guest-rx", queue->name);
+ if (IS_ERR(task))
+ goto kthread_err;
+ queue->task = task;
+
+ task = kthread_run(xenvif_dealloc_kthread, queue,
+ "%s-dealloc", queue->name);
+ if (IS_ERR(task))
+ goto kthread_err;
+ queue->dealloc_task = task;
+
if (tx_evtchn == rx_evtchn) {
/* feature-split-event-channels == 0 */
err = bind_interdomain_evtchn_to_irqhandler(
queue->vif->domid, tx_evtchn, xenvif_interrupt, 0,
queue->name, queue);
if (err < 0)
- goto err_unmap;
+ goto err;
queue->tx_irq = queue->rx_irq = err;
disable_irq(queue->tx_irq);
} else {
@@ -668,7 +714,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
queue->vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
queue->tx_irq_name, queue);
if (err < 0)
- goto err_unmap;
+ goto err;
queue->tx_irq = err;
disable_irq(queue->tx_irq);

@@ -678,47 +724,18 @@ int xenvif_connect_data(struct xenvif_queue *queue,
queue->vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
queue->rx_irq_name, queue);
if (err < 0)
- goto err_tx_unbind;
+ goto err;
queue->rx_irq = err;
disable_irq(queue->rx_irq);
}

- queue->stalled = true;
-
- task = kthread_create(xenvif_kthread_guest_rx,
- (void *)queue, "%s-guest-rx", queue->name);
- if (IS_ERR(task)) {
- pr_warn("Could not allocate kthread for %s\n", queue->name);
- err = PTR_ERR(task);
- goto err_rx_unbind;
- }
- queue->task = task;
- get_task_struct(task);
-
- task = kthread_create(xenvif_dealloc_kthread,
- (void *)queue, "%s-dealloc", queue->name);
- if (IS_ERR(task)) {
- pr_warn("Could not allocate kthread for %s\n", queue->name);
- err = PTR_ERR(task);
- goto err_rx_unbind;
- }
- queue->dealloc_task = task;
-
- wake_up_process(queue->task);
- wake_up_process(queue->dealloc_task);
-
return 0;

-err_rx_unbind:
- unbind_from_irqhandler(queue->rx_irq, queue);
- queue->rx_irq = 0;
-err_tx_unbind:
- unbind_from_irqhandler(queue->tx_irq, queue);
- queue->tx_irq = 0;
-err_unmap:
- xenvif_unmap_frontend_data_rings(queue);
- netif_napi_del(&queue->napi);
+kthread_err:
+ pr_warn("Could not allocate kthread for %s\n", queue->name);
+ err = PTR_ERR(task);
err:
+ xenvif_disconnect_queue(queue);
return err;
}

@@ -746,30 +763,7 @@ void xenvif_disconnect_data(struct xenvif *vif)
for (queue_index = 0; queue_index < num_queues; ++queue_index) {
queue = &vif->queues[queue_index];

- netif_napi_del(&queue->napi);
-
- if (queue->task) {
- kthread_stop(queue->task);
- put_task_struct(queue->task);
- queue->task = NULL;
- }
-
- if (queue->dealloc_task) {
- kthread_stop(queue->dealloc_task);
- queue->dealloc_task = NULL;
- }
-
- if (queue->tx_irq) {
- if (queue->tx_irq == queue->rx_irq)
- unbind_from_irqhandler(queue->tx_irq, queue);
- else {
- unbind_from_irqhandler(queue->tx_irq, queue);
- unbind_from_irqhandler(queue->rx_irq, queue);
- }
- queue->tx_irq = 0;
- }
-
- xenvif_unmap_frontend_data_rings(queue);
+ xenvif_disconnect_queue(queue);
}

xenvif_mcast_addr_list_free(vif);
--
2.16.4