Re: [Minios-devel] [UNIKRAFT PATCH 9/9] plat/xen/drivers/9p: Add bottom-half handler

[Costin Lupu <costin.lup@xxxxxxxxx>]

Reviewed-by: Costin Lupu <costin.lupu@xxxxxxxxx>

On 9/7/19 1:22 PM, Vlad-Andrei BĂDOIU (78692) wrote:
> From: Cristian Banu <cristb@xxxxxxxxx>
> 
> This patch adds bottom-half handling to Xen 9P by creating one thread
> per ring which waits on data to arrive.
> 
> Signed-off-by: Cristian Banu <cristb@xxxxxxxxx>
> ---
>  plat/xen/drivers/9p/9pfront.c | 53 ++++++++++++++++++++++++++++++++++-
>  plat/xen/drivers/9p/9pfront.h | 13 +++++++++
>  2 files changed, 65 insertions(+), 1 deletion(-)
> 
> diff --git a/plat/xen/drivers/9p/9pfront.c b/plat/xen/drivers/9p/9pfront.c
> index a5321898..da55fd61 100644
> --- a/plat/xen/drivers/9p/9pfront.c
> +++ b/plat/xen/drivers/9p/9pfront.c
> @@ -33,12 +33,16 @@
>   */
>  
>  #include <stdbool.h>
> +#include <stdio.h>
>  #include <uk/config.h>
>  #include <uk/alloc.h>
>  #include <uk/assert.h>
>  #include <uk/essentials.h>
>  #include <uk/errptr.h>
>  #include <uk/list.h>
> +#if CONFIG_LIBUKSCHED
> +#include <uk/thread.h>
> +#endif
>  #include <uk/9pdev.h>
>  #include <uk/9preq.h>
>  #include <uk/9pdev_trans.h>
> @@ -61,6 +65,23 @@ struct p9front_header {
>       uint16_t tag;
>  } __packed;
>  
> +static void p9front_recv(struct p9front_dev_ring *ring);
> +
> +#if CONFIG_LIBUKSCHED
> +
> +static void p9front_bh_handler(void *arg)
> +{
> +     struct p9front_dev_ring *ring = arg;
> +
> +     while (1) {
> +             uk_waitq_wait_event(&ring->bh_wq,
> +                             UK_READ_ONCE(ring->data_avail));
> +             p9front_recv(ring);
> +     }
> +}
> +
> +#endif
> +
>  static void p9front_recv(struct p9front_dev_ring *ring)
>  {
>       struct p9front_dev *p9fdev = ring->dev;
> @@ -79,6 +100,9 @@ static void p9front_recv(struct p9front_dev_ring *ring)
>               xen_rmb();
>  
>               if (xen_9pfs_queued(prod, cons, ring_size) < sizeof(hdr)) {
> +#if CONFIG_LIBUKSCHED
> +                     UK_WRITE_ONCE(ring->data_avail, false);
> +#endif
>                       notify_remote_via_evtchn(evtchn);
>                       return;
>               }
> @@ -144,7 +168,12 @@ static void p9front_handler(evtchn_port_t evtchn,
>        */
>       if (ring->dev->p9dev)
>               uk_9pdev_xmit_notify(ring->dev->p9dev);
> +#if CONFIG_LIBUKSCHED
> +     UK_WRITE_ONCE(ring->data_avail, true);
> +     uk_waitq_wake_up(&ring->bh_wq);
> +#else
>       p9front_recv(ring);
> +#endif
>  }
>  
>  static void p9front_free_dev_ring(struct p9front_dev *p9fdev, int idx)
> @@ -154,6 +183,9 @@ static void p9front_free_dev_ring(struct p9front_dev 
> *p9fdev, int idx)
>  
>       UK_ASSERT(ring->initialized);
>  
> +     if (ring->bh_thread_name)
> +             free(ring->bh_thread_name);
> +     uk_thread_kill(ring->bh_thread);
>       unbind_evtchn(ring->evtchn);
>       for (i = 0; i < (1 << p9fdev->ring_order); i++)
>               gnttab_end_access(ring->intf->ref[i]);
> @@ -226,12 +258,27 @@ static int p9front_allocate_dev_ring(struct p9front_dev 
> *p9fdev, int idx)
>       ring->data.in = data_bytes;
>       ring->data.out = data_bytes + XEN_FLEX_RING_SIZE(p9fdev->ring_order);
>  
> +#if CONFIG_LIBUKSCHED
> +     /* Allocate bottom-half thread. */
> +     ring->data_avail = false;
> +     uk_waitq_init(&ring->bh_wq);
> +
> +     rc = asprintf(&ring->bh_thread_name, DRIVER_NAME"-recv-%s-%u",
> +                     p9fdev->tag, idx);
> +     ring->bh_thread = uk_thread_create(ring->bh_thread_name,
> +                     p9front_bh_handler, ring);
> +     if (!ring->bh_thread) {
> +             rc = -ENOMEM;
> +             goto out_free_grants;
> +     }
> +#endif
> +
>       /* Allocate event channel. */
>       rc = evtchn_alloc_unbound(xendev->otherend_id, p9front_handler, ring,
>                               &ring->evtchn);
>       if (rc) {
>               uk_pr_err(DRIVER_NAME": Error creating evt channel: %d\n", rc);
> -             goto out_free_grants;
> +             goto out_free_thread;
>       }
>  
>       unmask_evtchn(ring->evtchn);
> @@ -241,6 +288,10 @@ static int p9front_allocate_dev_ring(struct p9front_dev 
> *p9fdev, int idx)
>  
>       return 0;
>  
> +out_free_thread:
> +     if (ring->bh_thread_name)
> +             free(ring->bh_thread_name);
> +     uk_thread_kill(ring->bh_thread);
>  out_free_grants:
>       for (i = 0; i < (1 << p9fdev->ring_order); i++)
>               gnttab_end_access(ring->intf->ref[i]);
> diff --git a/plat/xen/drivers/9p/9pfront.h b/plat/xen/drivers/9p/9pfront.h
> index 7cea61c5..0bbc7f44 100644
> --- a/plat/xen/drivers/9p/9pfront.h
> +++ b/plat/xen/drivers/9p/9pfront.h
> @@ -40,6 +40,9 @@
>  #include <uk/essentials.h>
>  #include <uk/list.h>
>  #include <uk/plat/spinlock.h>
> +#if CONFIG_LIBUKSCHED
> +#include <uk/sched.h>
> +#endif
>  #include <xen/io/9pfs.h>
>  #include <common/events.h>
>  #include <common/gnttab.h>
> @@ -59,6 +62,16 @@ struct p9front_dev_ring {
>       spinlock_t spinlock;
>       /* Tracks if this ring was initialized. */
>       bool initialized;
> +#if CONFIG_LIBUKSCHED
> +     /* Tracks if there is any data available on this ring. */
> +     bool data_avail;
> +     /* Bottom-half thread. */
> +     struct uk_thread *bh_thread;
> +     /* Bottom-half thread name. */
> +     char *bh_thread_name;
> +     /* Wait-queue on which the thread waits for available data. */
> +     struct uk_waitq bh_wq;
> +#endif
>  };
>  
>  struct p9front_dev {
> 

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