[UNIKRAFT/LWIP PATCH] Option to force polling mode

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Introduces an option to force polling mode for uknetdev devices
irrespective if the device supports interrupt-driven mode.
Because this option always causes 100% CPU utilization it should
be considered as workaround for cases where interrupt-based
handling performs badly.

Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
 Config.uk  | 14 ++++++++++++++
 uknetdev.c |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/Config.uk b/Config.uk
index 658e272..6d1fdb1 100644
--- a/Config.uk
+++ b/Config.uk
@@ -23,6 +23,20 @@ config LWIP_UKNETDEV
                driver does not support receive interrupts the network
                interfaces have to be polled manually (uknetdev_poll()).
 
+if LWIP_UKNETDEV
+config LWIP_UKNETDEV_POLLONLY
+       depends on LWIP_THREADS
+       bool "Force polling mode (workaround)"
+       default n
+       help
+               This option forces polling mode for uknetdev devices
+               irrespective if the device supports interrupt-driven
+               mode.
+               Because this option always causes 100% CPU utilization
+               it should be considered as workaround for cases where
+               interrupt-based handling performs badly.
+endif
+
 config LWIP_UKNETDEV_SCRATCH
        int
        default 64
diff --git a/uknetdev.c b/uknetdev.c
index 0524f12..b665830 100644
--- a/uknetdev.c
+++ b/uknetdev.c
@@ -477,6 +477,10 @@ err_t uknetdev_init(struct netif *nf)
        if (!lwip_data->dev_info.max_rx_queues
            || !lwip_data->dev_info.max_tx_queues)
                return ERR_IF;
+#if CONFIG_LWIP_UKNETDEV_POLLONLY
+       /* Unset receive interrupt support: We force polling mode */
+       lwip_data->dev_info.features &= ~UK_FEATURE_RXQ_INTR_AVAILABLE;
+#endif /* CONFIG_LWIP_UKNETDEV_POLLONLY */
        lwip_data->pkt_a = a;
 
        LWIP_DEBUGF(NETIF_DEBUG,
-- 
2.20.1