From patchwork Fri Aug 14 20:57:05 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antonio Quartulli X-Patchwork-Id: 507570 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 67BEA1401CB for ; Sat, 15 Aug 2015 06:57:36 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751976AbbHNU5b (ORCPT ); Fri, 14 Aug 2015 16:57:31 -0400 Received: from s1.neomailbox.net ([5.148.176.57]:45170 "EHLO s1.neomailbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751524AbbHNU52 (ORCPT ); Fri, 14 Aug 2015 16:57:28 -0400 From: Antonio Quartulli To: davem@davemloft.net Cc: netdev@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org, Sven Eckelmann , Marek Lindner , Antonio Quartulli Subject: [PATCH 01/10] batman-adv: Replace gw_reselect divisor with simple shift Date: Fri, 14 Aug 2015 22:57:05 +0200 Message-Id: <1439585834-26564-2-git-send-email-antonio@meshcoding.com> In-Reply-To: <1439585834-26564-1-git-send-email-antonio@meshcoding.com> References: <1439585834-26564-1-git-send-email-antonio@meshcoding.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Sven Eckelmann The gw_factor is divided by BATADV_TQ_LOCAL_WINDOW_SIZE ** 2 * 64. But the rest of the calculation has nothing to do with the tq window size and therefore the calculation is just (tmp_gw_factor / (64 ** 3)). Replace it with a simple shift to avoid a costly 64-bit divide when the max_gw_factor is changed from u32 to u64. This type change is necessary to avoid an overflow bug. Signed-off-by: Sven Eckelmann Signed-off-by: Marek Lindner Signed-off-by: Antonio Quartulli --- net/batman-adv/gateway_client.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index bb015862..e1e1f31 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -154,14 +154,10 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) struct batadv_neigh_ifinfo *router_ifinfo; struct batadv_gw_node *gw_node, *curr_gw = NULL; uint32_t max_gw_factor = 0, tmp_gw_factor = 0; - uint32_t gw_divisor; uint8_t max_tq = 0; uint8_t tq_avg; struct batadv_orig_node *orig_node; - gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE; - gw_divisor *= 64; - rcu_read_lock(); hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) { if (gw_node->deleted) @@ -187,7 +183,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) tmp_gw_factor = tq_avg * tq_avg; tmp_gw_factor *= gw_node->bandwidth_down; tmp_gw_factor *= 100 * 100; - tmp_gw_factor /= gw_divisor; + tmp_gw_factor >>= 18; if ((tmp_gw_factor > max_gw_factor) || ((tmp_gw_factor == max_gw_factor) &&