Patchwork [3.5.y.z,extended,stable] Patch "batman-adv: fix random jitter calculation" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Jan. 14, 2013, 8:58 p.m.
Message ID <>
Download mbox | patch
Permalink /patch/211915/
State Not Applicable
Delegated to: David Miller
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Herton Ronaldo Krzesinski - Jan. 14, 2013, 8:58 p.m.
This is a note to let you know that I have just added a patch titled

    batman-adv: fix random jitter calculation

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



From 12a62234843bc692176f3dc51492cfe84156f1c4 Mon Sep 17 00:00:00 2001
From: Akinobu Mita <>
Date: Wed, 26 Dec 2012 02:32:10 +0000
Subject: [PATCH] batman-adv: fix random jitter calculation

commit 143cdd8f33909ff5a153e3f02048738c5964ba26 upstream.

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

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: "David S. Miller" <>
Signed-off-by: David S. Miller <>
Signed-off-by: Herton Ronaldo Krzesinski <>
 net/batman-adv/bat_iv_ogm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


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diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index dc53798..bcf3760 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -117,7 +117,7 @@  static unsigned long bat_iv_ogm_emit_send_time(const struct bat_priv *bat_priv)
 	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 */