From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [ 57/80] batman-adv: fix random jitter calculation Date: Wed, 9 Jan 2013 12:35:49 -0800 Message-ID: <20130109201507.762332404@linuxfoundation.org> References: <20130109201500.410171651@linuxfoundation.org> Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Akinobu Mita , Antonio Quartulli , Marek Lindner , Simon Wunderlich , "David S. Miller" , b.a.t.m.a.n@lists.open-mesh.org, netdev@vger.kernel.org To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Return-path: In-Reply-To: <20130109201500.410171651@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Akinobu Mita [ Upstream commit 143cdd8f33909ff5a153e3f02048738c5964ba26 ] 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/bat_iv_ogm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -72,7 +72,7 @@ static unsigned long bat_iv_ogm_emit_sen { return jiffies + msecs_to_jiffies( atomic_read(&bat_priv->orig_interval) - - JITTER + (random32() % 2*JITTER)); + JITTER + (random32() % (2*JITTER))); } /* when do we schedule a ogm packet to be sent */