ethdev: release port

This patch adds rte_eth_dev_release_port(). The function is used for
changing an attached status of the device that has specified name.

Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>

lib/librte_ether/rte_ethdev.c

@@ -255,6 +255,17 @@ rte_eth_dev_allocate(const char *name)
 	return eth_dev;
 }
 
+int
+rte_eth_dev_release_port(struct rte_eth_dev *eth_dev)
+{
+	if (eth_dev == NULL)
+		return -EINVAL;
+
+	eth_dev->attached = 0;
+	nb_ports--;
+	return 0;
+}
+
 static int
 rte_eth_dev_init(struct rte_pci_driver *pci_drv,
 		 struct rte_pci_device *pci_dev)

lib/librte_ether/rte_ethdev.h

@@ -1539,6 +1539,18 @@ extern uint8_t rte_eth_dev_count(void);
  */
 struct rte_eth_dev *rte_eth_dev_allocate(const char *name);
 
+/**
+ * Function for internal use by dummy drivers primarily, e.g. ring-based
+ * driver.
+ * Release the specified ethdev port.
+ *
+ * @param eth_dev
+ * The *eth_dev* pointer is the address of the *rte_eth_dev* structure.
+ * @return
+ *   - 0 on success, negative on error
+ */
+int rte_eth_dev_release_port(struct rte_eth_dev *eth_dev);
+
 struct eth_driver;
 /**
  * @internal