From mboxrd@z Thu Jan 1 00:00:00 1970 From: Akinobu Mita Subject: [PATCH] batman-adv: fix random jitter calculation Date: Wed, 26 Dec 2012 21:32:10 +0900 Message-ID: <1356525130-2688-1-git-send-email-akinobu.mita@gmail.com> Cc: Akinobu Mita , Marek Lindner , Simon Wunderlich , Antonio Quartulli , b.a.t.m.a.n@lists.open-mesh.org, "David S. Miller" To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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); } -- 1.7.11.7