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

[Vlad-Andrei BĂDOIU (78692) <vlad_andrei.badoiu@xxxxxxxxxxxxxxx>]

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 {
-- 
2.20.1


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