[PATCH 1/2] kni: add API to set link status on kernel interface

[Dan Gora <dg@adax.com>]

Add a new API function to KNI, rte_kni_update_link() to allow DPDK
applications to update the link status for KNI network interfaces in
the linux kernel.

Signed-off-by: Dan Gora <dg@adax.com>
---
 lib/librte_kni/rte_kni.c | 57 ++++++++++++++++++++++++++++++++++++++++
 lib/librte_kni/rte_kni.h | 18 +++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
index 65f6a2b03..afe1d7410 100644
--- a/lib/librte_kni/rte_kni.c
+++ b/lib/librte_kni/rte_kni.c
@@ -790,6 +790,63 @@ rte_kni_unregister_handlers(struct rte_kni *kni)
 
 	return 0;
 }
+
+int
+rte_kni_update_link(struct rte_kni *kni, struct rte_eth_link *link)
+{
+	char path[64];
+	char carrier[2];
+	const char *new_carrier;
+	int fd, ret;
+
+	if (kni == NULL || link == NULL)
+		return -1;
+
+	snprintf(path, sizeof(path), "/sys/devices/virtual/net/%s/carrier",
+		kni->name);
+
+	fd = open(path, O_RDWR);
+	if (fd == -1) {
+		RTE_LOG(ERR, KNI, "Failed to open file: %s.\n", path);
+		return -1;
+	}
+
+	ret = read(fd, carrier, 2);
+	if (ret < 1) {
+		/* Cannot read carrier until interface is marked
+		 * 'up', so don't log an error.
+		 */
+		close(fd);
+		return -1;
+	}
+
+	new_carrier = (link->link_status == ETH_LINK_UP) ? "1" : "0";
+	ret = write(fd, new_carrier, 1);
+	if (ret < 1) {
+		RTE_LOG(ERR, KNI, "Failed to write file: %s.\n", path);
+		close(fd);
+		return -1;
+	}
+
+	if (strncmp(carrier, new_carrier, 1)) {
+		if (link->link_status == ETH_LINK_UP) {
+			RTE_LOG(INFO, KNI, "%s NIC Link is Up %d Mbps %s %s.\n",
+				kni->name,
+				link->link_speed,
+				link->link_autoneg ? "(Fixed)" : "(AutoNeg)",
+				link->link_duplex ?
+					"Full Duplex" : "Half Duplex");
+		} else {
+			RTE_LOG(INFO, KNI, "%s NIC Link is Down.\n",
+				kni->name);
+		}
+	}
+
+	close(fd);
+
+	return 0;
+}
+
 void
 rte_kni_close(void)
 {
diff --git a/lib/librte_kni/rte_kni.h b/lib/librte_kni/rte_kni.h
index 99055e2c2..4118ae97a 100644
--- a/lib/librte_kni/rte_kni.h
+++ b/lib/librte_kni/rte_kni.h
@@ -21,6 +21,7 @@
 #include <rte_memory.h>
 #include <rte_mempool.h>
 #include <rte_ether.h>
+#include <rte_ethdev.h>
 
 #include <exec-env/rte_kni_common.h>
 
@@ -228,6 +229,23 @@ int rte_kni_register_handlers(struct rte_kni *kni, struct rte_kni_ops *ops);
  */
 int rte_kni_unregister_handlers(struct rte_kni *kni);
 
+/**
+ * Update link status info for KNI port.
+ *
+ * Update the linkup/linkdown status of a KNI interface in the kernel.
+ *
+ * @param kni
+ *  pointer to struct rte_kni.
+ * @param link
+ *  pointer to struct rte_eth_link containing new interface status.
+ *
+ * @return
+ *  On success: 0
+ *  On failure: -1
+ */
+int __rte_experimental
+rte_kni_update_link(struct rte_kni *kni, struct rte_eth_link *link);
+
 /**
  *  Close KNI device.
  */
-- 
2.19.0