[dpdk-dev] [PATCH v4 1/6] 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           | 41 ++++++++++++++++++++++++++++++
 lib/librte_kni/rte_kni.h           | 20 +++++++++++++++
 lib/librte_kni/rte_kni_version.map |  6 +++++
 3 files changed, 67 insertions(+)

diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
index b8edd40f4..c9726d4f8 100644
--- a/lib/librte_kni/rte_kni.c
+++ b/lib/librte_kni/rte_kni.c
@@ -717,6 +717,47 @@ rte_kni_unregister_handlers(struct rte_kni *kni)
 
 	return 0;
 }
+
+int __rte_experimental
+rte_kni_update_link(struct rte_kni *kni, unsigned int linkup)
+{
+	char path[64];
+	char old_carrier[2];
+	const char *new_carrier;
+	int old_linkup;
+	int fd, ret;
+
+	if (kni == 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, old_carrier, 2);
+	if (ret < 1) {
+		close(fd);
+		return -1;
+	}
+	old_linkup = (old_carrier[0] == '1');
+
+	new_carrier = linkup ? "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;
+	}
+
+	close(fd);
+	return old_linkup;
+}
+
 void
 rte_kni_close(void)
 {
diff --git a/lib/librte_kni/rte_kni.h b/lib/librte_kni/rte_kni.h
index 601abdfc6..02ca43b4b 100644
--- a/lib/librte_kni/rte_kni.h
+++ b/lib/librte_kni/rte_kni.h
@@ -232,6 +232,26 @@ 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 carrier state for KNI port.
+ *
+ * Update the linkup/linkdown state of a KNI interface in the kernel.
+ *
+ * @param kni
+ *  pointer to struct rte_kni.
+ * @param linkup
+ *  New link state:
+ *  0 for linkdown.
+ *  > 0 for linkup.
+ *
+ * @return
+ *  On failure: -1
+ *  Previous link state == linkdown: 0
+ *  Previous link state == linkup: 1
+ */
+int __rte_experimental
+rte_kni_update_link(struct rte_kni *kni, unsigned int linkup);
+
 /**
  *  Close KNI device.
  */
diff --git a/lib/librte_kni/rte_kni_version.map b/lib/librte_kni/rte_kni_version.map
index acd515eb0..c877dc6aa 100644
--- a/lib/librte_kni/rte_kni_version.map
+++ b/lib/librte_kni/rte_kni_version.map
@@ -15,3 +15,9 @@ DPDK_2.0 {
 
 	local: *;
 };
+
+EXPERIMENTAL {
+	global:
+
+	rte_kni_update_link;
+};
-- 
2.19.0