devargs: introduce iterator

In preparation to making devargs_list private.

Bus drivers generally need to access rte_devargs pertaining to their
operations. This match is a common operation for bus drivers.

Add a new accessor for the rte_devargs list.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>

lib/librte_eal/common/eal_common_devargs.c

@@ -207,3 +207,23 @@ rte_eal_devargs_dump(FILE *f)
 			devargs->name, devargs->args);
 	}
 }
+
+/* bus-aware rte_devargs iterator. */
+__rte_experimental
+struct rte_devargs *
+rte_eal_devargs_next(const char *busname, const struct rte_devargs *start)
+{
+	struct rte_devargs *da;
+
+	if (start != NULL)
+		da = TAILQ_NEXT(start, next);
+	else
+		da = TAILQ_FIRST(&devargs_list);
+	while (da != NULL) {
+		if (busname == NULL ||
+		    (strcmp(busname, da->bus->name) == 0))
+			return da;
+		da = TAILQ_NEXT(da, next);
+	}
+	return NULL;
+}

lib/librte_eal/common/include/rte_devargs.h

@@ -189,6 +189,34 @@ rte_eal_devargs_type_count(enum rte_devtype devtype);
  */
 void rte_eal_devargs_dump(FILE *f);
 
+/**
+ * Find next rte_devargs matching the provided bus name.
+ *
+ * @param busname
+ *   Limit the iteration to devargs related to buses
+ *   matching this name.
+ *   Will return any next rte_devargs if NULL.
+ *
+ * @param start
+ *   Starting iteration point. The iteration will start at
+ *   the first rte_devargs if NULL.
+ *
+ * @return
+ *   Next rte_devargs entry matching the requested bus,
+ *   NULL if there is none.
+ */
+__rte_experimental
+struct rte_devargs *
+rte_eal_devargs_next(const char *busname, const struct rte_devargs *start);
+
+/**
+ * Iterate over all rte_devargs for a specific bus.
+ */
+#define RTE_EAL_DEVARGS_FOREACH(busname, da) \
+	for (da = rte_eal_devargs_next(busname, NULL); \
+	     da != NULL; \
+	     da = rte_eal_devargs_next(busname, da)) \
+
 #ifdef __cplusplus
 }
 #endif

lib/librte_eal/rte_eal_version.map

@@ -220,6 +220,7 @@ EXPERIMENTAL {
 	rte_dev_event_monitor_stop;
 	rte_eal_cleanup;
 	rte_eal_devargs_insert;
+	rte_eal_devargs_next;
 	rte_eal_devargs_parse;
 	rte_eal_devargs_remove;
 	rte_eal_hotplug_add;