From patchwork Wed Dec 26 12:32:10 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Akinobu Mita X-Patchwork-Id: 2651 Return-Path: Received: from mail-pa0-f42.google.com (mail-pa0-f42.google.com [209.85.220.42]) by open-mesh.org (Postfix) with ESMTPS id 5E8C36019AE for ; Wed, 26 Dec 2012 13:32:47 +0100 (CET) Received: by mail-pa0-f42.google.com with SMTP id rl6so4926144pac.29 for ; Wed, 26 Dec 2012 04:32:46 -0800 (PST) X-Received: by 10.68.253.230 with SMTP id ad6mr85952241pbd.84.1356525166310; Wed, 26 Dec 2012 04:32:46 -0800 (PST) Received: from localhost.localdomain (p2126-ipbf3106hodogaya.kanagawa.ocn.ne.jp. [114.149.157.126]) by mx.google.com with ESMTPS id ty4sm15845652pbc.57.2012.12.26.04.32.43 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 26 Dec 2012 04:32:45 -0800 (PST) From: Akinobu Mita To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Date: Wed, 26 Dec 2012 21:32:10 +0900 Message-Id: <1356525130-2688-1-git-send-email-akinobu.mita@gmail.com> X-Mailer: git-send-email 1.7.11.7 Cc: b.a.t.m.a.n@lists.open-mesh.org, Akinobu Mita , Simon Wunderlich , Marek Lindner , "David S. Miller" Subject: [B.A.T.M.A.N.] [PATCH] batman-adv: fix random jitter calculation X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Dec 2012 12:32:48 -0000 batadv_iv_ogm_emit_send_time() attempts to calculates a random integer in the range of 'orig_interval +- BATADV_JITTER' by the below lines. msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER; msecs += (random32() % 2 * BATADV_JITTER); But it actually gets 'orig_interval' or 'orig_interval - BATADV_JITTER' because '%' and '*' have same precedence and associativity is left-to-right. This adds the parentheses at the appropriate position so that it matches original intension. Signed-off-by: Akinobu Mita Acked-by: Antonio Quartulli Cc: Marek Lindner Cc: Simon Wunderlich Cc: Antonio Quartulli Cc: b.a.t.m.a.n@lists.open-mesh.org Cc: "David S. Miller" Cc: netdev@vger.kernel.org --- This patch is extracted from the patch series "rename random32 and net_random to prandom" since it is a fix. net/batman-adv/bat_iv_ogm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c index 9f3925a..7d02ebd 100644 --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -123,7 +123,7 @@ batadv_iv_ogm_emit_send_time(const struct batadv_priv *bat_priv) unsigned int msecs; msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER; - msecs += (random32() % 2 * BATADV_JITTER); + msecs += random32() % (2 * BATADV_JITTER); return jiffies + msecs_to_jiffies(msecs); }