From: Gaetan Rivet <gaetan.rivet@6wind.com>
Date: Tue, 29 Aug 2017 16:19:48 +0000 (+0200)
Subject: bus: skip useless iterations in find function
X-Git-Tag: spdx-start~1228
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=96d9dd74cde0ba14ec99c806ab25ff9b992c58d6;p=dpdk.git

bus: skip useless iterations in find function

The starting point is known. The iterator can be directly set to it.

The function rte_bus_find can easily be used with a comparison function
always returning True. This would make it a regular bus iterator.

Users doing so would however accomplish such iteration in

   O(N * N/2) = O(N^2)

Which can be avoided.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
---

diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
index c3c77f42fd..5c63ced61e 100644
--- a/lib/librte_eal/common/eal_common_bus.c
+++ b/lib/librte_eal/common/eal_common_bus.c
@@ -146,15 +146,16 @@ struct rte_bus *
 rte_bus_find(const struct rte_bus *start, rte_bus_cmp_t cmp,
 	     const void *data)
 {
-	struct rte_bus *bus = NULL;
+	struct rte_bus *bus;
 
-	TAILQ_FOREACH(bus, &rte_bus_list, next) {
-		if (start && bus == start) {
-			start = NULL; /* starting point found */
-			continue;
-		}
+	if (start != NULL)
+		bus = TAILQ_NEXT(start, next);
+	else
+		bus = TAILQ_FIRST(&rte_bus_list);
+	while (bus != NULL) {
 		if (cmp(bus, data) == 0)
 			break;
+		bus = TAILQ_NEXT(bus, next);
 	}
 	return bus;
 }