ethdev: add private generic device iterator

This iterator can be customized with a comparison function that will
trigger a stopping condition.

It can be leveraged to write several different iterators that have
similar but non-identical purposes.

It is private to librte_ethdev.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>

lib/librte_ethdev/Makefile

@@ -18,6 +18,7 @@ EXPORT_MAP := rte_ethdev_version.map
 
 LIBABIVER := 10
 
+SRCS-y += ethdev_private.c
 SRCS-y += rte_ethdev.c
 SRCS-y += rte_flow.c
 SRCS-y += rte_tm.c

lib/librte_ethdev/ethdev_private.c

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018 Gaëtan Rivet
+ */
+
+#include "rte_ethdev.h"
+#include "ethdev_private.h"
+
+struct rte_eth_dev *
+eth_find_device(const struct rte_eth_dev *start, rte_eth_cmp_t cmp,
+		const void *data)
+{
+	struct rte_eth_dev *edev;
+	ptrdiff_t idx;
+
+	/* Avoid Undefined Behaviour */
+	if (start != NULL &&
+	    (start < &rte_eth_devices[0] ||
+	     start > &rte_eth_devices[RTE_MAX_ETHPORTS]))
+		return NULL;
+	if (start != NULL)
+		idx = start - &rte_eth_devices[0] + 1;
+	else
+		idx = 0;
+	for (; idx < RTE_MAX_ETHPORTS; idx++) {
+		edev = &rte_eth_devices[idx];
+		if (cmp(edev, data) == 0)
+			return edev;
+	}
+	return NULL;
+}
+

lib/librte_ethdev/ethdev_private.h

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018 Gaëtan Rivet
+ */
+
+#ifndef _RTE_ETH_PRIVATE_H_
+#define _RTE_ETH_PRIVATE_H_
+
+#include "rte_ethdev.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Generic rte_eth_dev comparison function. */
+typedef int (*rte_eth_cmp_t)(const struct rte_eth_dev *, const void *);
+
+/* Generic rte_eth_dev iterator. */
+struct rte_eth_dev *
+eth_find_device(const struct rte_eth_dev *_start, rte_eth_cmp_t cmp,
+		const void *data);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_ETH_PRIVATE_H_ */

lib/librte_ethdev/meson.build

@@ -4,7 +4,8 @@
 name = 'ethdev'
 version = 10
 allow_experimental_apis = true
-sources = files('ethdev_profile.c',
+sources = files('ethdev_private.c',
+	'ethdev_profile.c',
 	'rte_ethdev.c',
 	'rte_flow.c',
 	'rte_mtr.c',