batman-adv/patches/0006-batman-adv-Make-MCAST-capability-changes-atomic.patch

   1 From 201a54ba710ab7f40b82ad3c109f702c47d0761f Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>
   3 Date: Tue, 16 Jun 2015 17:10:25 +0200
   4 Subject: [PATCH 06/13] batman-adv: Make MCAST capability changes atomic
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   8
   9 Bitwise OR/AND assignments in C aren't guaranteed to be atomic. One
  10 OGM handler might undo the set/clear of a specific bit from another
  11 handler run in between.
  12
  13 Fix this by using the atomic set_bit()/clear_bit() functions.
  14
  15 Fixes: 77ec494490d6 ("batman-adv: Announce new capability via multicast TVLV")
  16 Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
  17 Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
  18 ---
  19  multicast.c | 6 +++---
  20  1 file changed, 3 insertions(+), 3 deletions(-)
  21
  22 diff --git a/multicast.c b/multicast.c
  23 index 09f2838..00612bf 100644
  24 --- a/multicast.c
  25 +++ b/multicast.c
  26 @@ -684,7 +684,7 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
  27             !(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST)) {
  28                 if (orig_initialized)
  29                         atomic_dec(&bat_priv->mcast.num_disabled);
  30 -               orig->capabilities |= BATADV_ORIG_CAPA_HAS_MCAST;
  31 +               set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
  32         /* If mcast support is being switched off or if this is an initial
  33          * OGM without mcast support then increase the disabled mcast
  34          * node counter.
  35 @@ -693,10 +693,10 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
  36                    (orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST ||
  37                     !orig_initialized)) {
  38                 atomic_inc(&bat_priv->mcast.num_disabled);
  39 -               orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_MCAST;
  40 +               clear_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
  41         }
  42
  43 -       orig->capa_initialized |= BATADV_ORIG_CAPA_HAS_MCAST;
  44 +       set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized);
  45
  46         if (orig_mcast_enabled && tvlv_value &&
  47             (tvlv_value_len >= sizeof(mcast_flags)))
  48 --
  49 2.1.4
  50