[UNIKRAFT PATCH v3 14/16] plat/tap: Support tap_netdev_recv

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Implement receive on the tap device.

Signed-off-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>
---
 plat/drivers/include/tap/tap.h |  1 +
 plat/drivers/tap/tap.c         | 48 +++++++++++++++++++++++++++++++++-
 plat/linuxu/tap_io.c           | 13 +++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/plat/drivers/include/tap/tap.h b/plat/drivers/include/tap/tap.h
index 42c6d7f1..f3e1b3eb 100644
--- a/plat/drivers/include/tap/tap.h
+++ b/plat/drivers/include/tap/tap.h
@@ -45,5 +45,6 @@ int tap_close(int fd);
 int tap_dev_configure(int fd, __u32 feature_flags, void *arg);
 int tap_netif_configure(int fd, __u32 request, void *arg);
 int tap_netif_create(void);
+__ssz tap_read(int fd, void *buf, size_t count);
 
 #endif /* __PLAT_DRV_TAP_H */
diff --git a/plat/drivers/tap/tap.c b/plat/drivers/tap/tap.c
index b7037b64..03948150 100644
--- a/plat/drivers/tap/tap.c
+++ b/plat/drivers/tap/tap.c
@@ -254,12 +254,58 @@ static int tap_netdev_recv(struct uk_netdev *dev,
                           struct uk_netdev_rx_queue *queue,
                           struct uk_netbuf **pkt)
 {
-       int rc = -EINVAL;
+       int rc = 0;
+       struct tap_net_dev *tdev __maybe_unused;
+       struct uk_netbuf *_pkt = NULL;
 
        UK_ASSERT(dev);
        UK_ASSERT(queue && pkt);
 
+       tdev = to_tapnetdev(dev);
+
+       if (!queue->alloc_rxpkts)
+               return -EINVAL;
+
+
+       /**
+        * Allocate the packet in which the packet will be received.
+        */
+       rc = queue->alloc_rxpkts(queue->alloc_rxpkts_argp, &_pkt, 1);
+       if (rc == 0) {
+               uk_pr_err(DRIVER_NAME": Failed to allocate the memory\n");
+               rc = -ENOMEM;
+               _pkt = NULL;
+               rc = UK_NETDEV_STATUS_UNDERRUN | UK_NETDEV_STATUS_MORE;
+               return rc;
+       }
+       uk_pr_debug(DRIVER_NAME": Receiving on interface %s(%d) %p(%d)\n",
+                   tdev->name, queue->fd, _pkt->data, _pkt->len);
+       rc = tap_read(queue->fd, _pkt->data, _pkt->len);
+
+       if (rc > 0) {
+               uk_pr_debug(DRIVER_NAME": Recv pkt size: %d\n", rc);
+               /* Setting the length of the packet */
+               _pkt->len = rc;
+               rc = UK_NETDEV_STATUS_SUCCESS | UK_NETDEV_STATUS_MORE;
+       } else if (rc == 0 || rc == -EWOULDBLOCK || rc == -EAGAIN) {
+               rc = 0;
+               goto err_exit;
+       } else {
+               uk_pr_err(DRIVER_NAME": Failed(%d) to read the packet\n", rc);
+               goto err_exit;
+       }
+       uk_pr_debug("uk_netdev buf ptr: %p\n", _pkt);
+
+       *pkt = _pkt;
+
+exit:
        return rc;
+
+err_exit:
+       if (_pkt)
+               uk_netbuf_free(_pkt);
+       *pkt = NULL;
+       goto exit;
 }
 
 static int tap_netdev_xmit(struct uk_netdev *dev,
diff --git a/plat/linuxu/tap_io.c b/plat/linuxu/tap_io.c
index 8c44281c..1072c60f 100644
--- a/plat/linuxu/tap_io.c
+++ b/plat/linuxu/tap_io.c
@@ -109,6 +109,19 @@ int tap_netif_create(void)
        return sys_socket(AF_INET, SOCK_DGRAM, 0);
 }
 
+ssize_t tap_read(int fd, void *buf, size_t count)
+{
+       ssize_t rc = -EINTR;
+
+       while (rc == -EINTR)
+               rc = sys_read(fd, buf, count);
+
+       if (rc < 0)
+               uk_pr_err("Failed(%ld) to read from the tap device\n", rc);
+
+       return rc;
+}
+
 int tap_close(int fd)
 {
        return sys_close(fd);
-- 
2.20.1