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    Subject[PATCH 182/222] batman-adv: fix random jitter calculation
    Date
    3.5.7.3 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Akinobu Mita <akinobu.mita@gmail.com>

    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
    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>
    Acked-by: Antonio Quartulli <ordex@autistici.org>
    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
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
    ---
    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 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 */
    --
    1.7.9.5


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