[UNIKRAFT/LIBLWIP PATCH v2 3/3] lib/lwip: Enable poll only receive

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

The uknetdev library provides the way to check if interrupts are
supported on a uk_netdev. If the device does not support interrupt
the lwip stack would create a thread to poll the receive queue for
packets.

Signed-off-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>
---
 uknetdev.c | 91 ++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 68 insertions(+), 23 deletions(-)

diff --git a/uknetdev.c b/uknetdev.c
index ef57014..0831204 100644
--- a/uknetdev.c
+++ b/uknetdev.c
@@ -64,6 +64,11 @@
 
 struct lwip_netdev_data {
        uint32_t features;
+#ifdef CONFIG_HAVE_SCHED
+       struct uk_thread *poll_thread; /* Thread per device */
+       char *_name; /* Thread name */
+       struct uk_sched *sched; /* Scheduler information */
+#endif /* CONFIG_HAVE_SCHED */
 };
 
 /*
@@ -325,44 +330,84 @@ void uknetdev_poll_all(void)
 
 #else /* CONFIG_LWIP_NOTHREADS */
 
+static void _poll_netif(void *arg)
+{
+       struct netif *nf = (struct netif *) arg;
+
+       while (1) {
+               uknetdev_poll(nf);
+               uk_sched_yield();
+       }
+}
+
 static void uknetdev_updown(struct netif *nf)
 {
        struct uk_netdev *dev;
        int ret;
+       struct lwip_netdev_data  *lwip_data;
 
        UK_ASSERT(nf);
        dev = netif_to_uknetdev(nf);
        UK_ASSERT(dev);
+       lwip_data = (struct lwip_netdev_data *)dev->scratch_pad;
 
        /* Enable and disable interrupts according to netif's up/down status */
+
        if (nf->flags & NETIF_FLAG_UP) {
-               ret = uk_netdev_rxq_intr_enable(dev, 0);
-               if (ret < 0) {
-                       LWIP_DEBUGF(NETIF_DEBUG,
-                                   ("%s: %c%c%u: Failed to enable rx 
interrrupt mode on netdev %u\n",
-                                    __func__, nf->name[0], nf->name[1],
-                                    nf->num, uk_netdev_id_get(dev)));
+               if (uk_netdev_rxintr_supported(lwip_data->features)) {
+                       ret = uk_netdev_rxq_intr_enable(dev, 0);
+                       if (ret < 0) {
+                               LWIP_DEBUGF(NETIF_DEBUG,
+                                               ("%s: %c%c%u: Failed to enable 
rx interrupt mode on netdev %u\n",
+                                                __func__, nf->name[0],
+                                                nf->name[1],
+                                                nf->num,
+                                                uk_netdev_id_get(dev)));
+                       } else {
+                               LWIP_DEBUGF(NETIF_DEBUG,
+                                       ("%s: %c%c%u: Enabled rx interrupt mode 
on netdev %u\n",
+                                                __func__, nf->name[0],
+                                                nf->name[1],
+                                                nf->num,
+                                                uk_netdev_id_get(dev)));
+                       }
+
+                       if (ret == 1) {
+                               /*
+                                * uk_netdev_rxq_intr_enable() told us that we
+                                * need to flush the receieve queue before
+                                * interrupts are enabled. For this purpose
+                                * we do an initial poll.
+                                */
+                               uknetdev_poll(nf);
+                       }
                } else {
+#ifdef CONFIG_HAVE_SCHED
                        LWIP_DEBUGF(NETIF_DEBUG,
-                                   ("%s: %c%c%u: Enabled rx interrupt mode on 
netdev %u\n",
-                                    __func__, nf->name[0], nf->name[1],
-                                    nf->num, uk_netdev_id_get(dev)));
-               }
-
-               if (ret == 1) {
-                       /*
-                        * uk_netdev_rxq_intr_enable() told us that we need to
-                        * flush the receieve queue before interrupts are
-                        * enabled. For this purpose we do an initial poll.
-                        */
-                       uknetdev_poll(nf);
+                                       ("%s: Poll receive enabled\n",
+                                        __func__));
+                       /* Create a thread */
+                       lwip_data->sched = uk_sched_get_default();
+                       UK_ASSERT(lwip_data->sched);
+                       lwip_data->poll_thread =
+                               uk_sched_thread_create(lwip_data->sched, NULL,
+                                                      NULL, _poll_netif, nf);
+#else /* CONFIG_HAVE_SCHED */
+                       uk_pr_warn("The netdevice does not support interrupt. 
Ensure the netdevice is polled to receive packets");
+#endif /* CONFIG_HAVE_SCHED */
                }
        } else {
-               uk_netdev_rxq_intr_disable(dev, 0);
-               LWIP_DEBUGF(NETIF_DEBUG,
-                           ("%s: %c%c%u: Disabled rx interrupts on netdev 
%u\n",
-                            __func__, nf->name[0], nf->name[1],
-                            nf->num, uk_netdev_id_get(dev)));
+               /**
+                * TODO:
+                * Cleanup the thread on stopping the network interface.
+                */
+               if (uk_netdev_rxintr_supported(lwip_data->features)) {
+                       uk_netdev_rxq_intr_disable(dev, 0);
+                       LWIP_DEBUGF(NETIF_DEBUG,
+                                       ("%s: %c%c%u: Disabled rx interrupts on 
netdev %u\n",
+                                        __func__, nf->name[0], nf->name[1],
+                                        nf->num, uk_netdev_id_get(dev)));
+               }
 
        }
 }
-- 
2.20.1