[PATCH 19/29] batman-adv: fix random jitter calculation

Akinobu Mita
2012-12-24T02:22:39Z

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 <akinobu.mita@gmail.com>
Cc: Marek Lindner <lindner_marek@yahoo.de>
Cc: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Cc: Antonio Quartulli <ordex@autistici.org>
Cc: b.a.t.m.a.n@lists.open-mesh.org
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
---
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