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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] xen/netback: cleanup init and deinit code
On Mon, 14 Oct 2019 at 10:09, Juergen Gross <jgross@xxxxxxxx> wrote:
>
> 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().
I guess the reason it was done that way was to ensure that queue->task
and queue->dealloc_task would be set before the relevant threads
executed, but I don't see anywhere relying on this so I guess change
is safe. The rest of it looks fine.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Paul Durrant <paul@xxxxxxx>
> ---
> 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
>
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