[RFC 05/13] net/ring: add argument to attach existing ring

[Stephen Hemminger <stephen@networkplumber.org>]

Need ability to allow process like dumpcap to make a ring ethdev
with a pre-existing ring. Do this via devargs so it can work
with hotplug.

The API rte_eth_from_ring() doesn't do this.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/net/ring/rte_eth_ring.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/net/ring/rte_eth_ring.c b/drivers/net/ring/rte_eth_ring.c
index 966c64d9a5..94a739a925 100644
--- a/drivers/net/ring/rte_eth_ring.c
+++ b/drivers/net/ring/rte_eth_ring.c
@@ -23,9 +23,12 @@
 #define ETH_RING_INTERNAL_ARG		"internal"
 #define ETH_RING_INTERNAL_ARG_MAX_LEN	19 /* "0x..16chars..\0" */
 
+#define ETH_RING_RING_ARG		"ring"
+
 static const char *valid_arguments[] = {
 	ETH_RING_NUMA_NODE_ACTION_ARG,
 	ETH_RING_INTERNAL_ARG,
+	ETH_RING_RING_ARG,
 	NULL
 };
 
@@ -693,6 +696,20 @@ parse_internal_args(const char *key __rte_unused, const char *value,
 	return 0;
 }
 
+static int
+parse_ring_arg(const char *key __rte_unused, const char *value, void *data)
+{
+	struct rte_ring **rp = data;
+
+	*rp = rte_ring_lookup(value);
+	if (*rp == NULL) {
+		PMD_LOG(ERR, "ring '%s' not found", value);
+		return -1;
+	}
+
+	return 0;
+}
+
 static int
 rte_pmd_ring_probe(struct rte_vdev_device *dev)
 {
@@ -770,6 +787,18 @@ rte_pmd_ring_probe(struct rte_vdev_device *dev)
 				&eth_dev);
 			if (ret >= 0)
 				ret = 0;
+		} else if (rte_kvargs_count(kvlist, ETH_RING_RING_ARG) == 1) {
+			struct rte_ring *rxtx[1] = { };
+
+			ret = rte_kvargs_process(kvlist, ETH_RING_RING_ARG, parse_ring_arg, rxtx);
+			if (ret < 0)
+				goto out_free;
+
+			/* Note: rte_eth_from_ring() does not do what is expected here! */
+			ret = do_eth_dev_ring_create(name, dev, rxtx, 1, rxtx, 1,
+						     rte_socket_id(), DEV_ATTACH, &eth_dev);
+			if (ret < 0)
+				goto out_free;
 		} else {
 			ret = rte_kvargs_count(kvlist, ETH_RING_NUMA_NODE_ACTION_ARG);
 			info = rte_zmalloc("struct node_action_list",
@@ -843,4 +872,5 @@ static struct rte_vdev_driver pmd_ring_drv = {
 RTE_PMD_REGISTER_VDEV(net_ring, pmd_ring_drv);
 RTE_PMD_REGISTER_ALIAS(net_ring, eth_ring);
 RTE_PMD_REGISTER_PARAM_STRING(net_ring,
+	ETH_RING_RING_ARG "=<string> "
 	ETH_RING_NUMA_NODE_ACTION_ARG "=name:node:action(ATTACH|CREATE)");
-- 
2.47.2