[dpdk-dev] [PATCH 3/4] ethdev: count devices consistently

[Gaetan Rivet <gaetan.rivet@6wind.com>]

Make the rte_eth_dev_count() return the correct number of devices even
after some are detached by the hotplug API.

This change does not affect existing applications that do not use
hotplug API calls. Those that do are already aware that port IDs are not
necessarily contiguous.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
---
 lib/librte_ether/rte_ethdev.c | 20 ++++++++++----------
 lib/librte_ether/rte_ethdev.h | 14 ++++++++------
 2 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
index fcb9933..3a52d0a 100644
--- a/lib/librte_ether/rte_ethdev.c
+++ b/lib/librte_ether/rte_ethdev.c
@@ -72,7 +72,6 @@ static const char *MZ_RTE_ETH_DEV_DATA = "rte_eth_dev_data";
 struct rte_eth_dev rte_eth_devices[RTE_MAX_ETHPORTS];
 static struct rte_eth_dev_data *rte_eth_dev_data;
 static uint8_t eth_dev_last_created_port;
-static uint8_t nb_ports;
 
 /* spinlock for eth device callbacks */
 static rte_spinlock_t rte_eth_dev_cb_lock = RTE_SPINLOCK_INITIALIZER;
@@ -207,7 +206,6 @@ eth_dev_get(uint8_t port_id)
 	TAILQ_INIT(&(eth_dev->link_intr_cbs));
 
 	eth_dev_last_created_port = port_id;
-	nb_ports++;
 
 	return eth_dev;
 }
@@ -280,7 +278,6 @@ rte_eth_dev_release_port(struct rte_eth_dev *eth_dev)
 		return -EINVAL;
 
 	eth_dev->state = RTE_ETH_DEV_UNUSED;
-	nb_ports--;
 	return 0;
 }
 
@@ -401,7 +398,15 @@ rte_eth_dev_socket_id(uint8_t port_id)
 uint8_t
 rte_eth_dev_count(void)
 {
-	return nb_ports;
+	uint8_t p;
+	uint8_t count;
+
+	count = 0;
+
+	RTE_ETH_FOREACH_DEV(p)
+		count++;
+
+	return count;
 }
 
 int
@@ -433,13 +438,8 @@ rte_eth_dev_get_port_by_name(const char *name, uint8_t *port_id)
 		return -EINVAL;
 	}
 
-	if (!nb_ports)
-		return -ENODEV;
-
 	*port_id = RTE_MAX_ETHPORTS;
-
-	for (i = 0; i < RTE_MAX_ETHPORTS; i++) {
-
+	RTE_ETH_FOREACH_DEV(i) {
 		if (!strncmp(name,
 			rte_eth_dev_data[i].name, strlen(name))) {
 
diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index 59c4123..bdad81b 100644
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -1743,9 +1743,9 @@ uint8_t rte_eth_find_next(uint8_t port_id);
 /**
  * Macro to iterate over all enabled ethdev ports.
  */
-#define RTE_ETH_FOREACH_DEV(p)			\
-	for (p = rte_eth_find_next(0);		\
-	     p < RTE_MAX_ETHPORTS;		\
+#define RTE_ETH_FOREACH_DEV(p)					\
+	for (p = rte_eth_find_next(0);				\
+	     (unsigned int)p < (unsigned int)RTE_MAX_ETHPORTS;	\
 	     p = rte_eth_find_next(p + 1))
 
 
@@ -1755,9 +1755,11 @@ uint8_t rte_eth_find_next(uint8_t port_id);
  * All devices whose port identifier is in the range
  * [0,  rte_eth_dev_count() - 1] can be operated on by network applications
  * immediately after invoking rte_eal_init().
- * If the application unplugs a port using hotplug function, The enabled port
- * numbers may be noncontiguous. In the case, the applications need to manage
- * enabled port by themselves.
+ * If the application unplugs a port using a hotplug function, the range of
+ * enabled ports may be non-contiguous. In this case, this function returns
+ * the actual number of enabled ports and the application must keep track
+ * of possible gaps in the enabled range, or use the ``RTE_ETH_FOREACH_DEV()``
+ * macro.
  *
  * @return
  *   - The total number of usable Ethernet devices.
-- 
2.1.4