batman-adv: Make TT capability changes atomic

commit ac4eebd48461ec993e7cb614d5afe7df8c72e6b7 upstream.

Bitwise OR/AND assignments in C aren't guaranteed to be atomic. One
OGM handler might undo the set/clear of a specific bit from another
handler run in between.

Fix this by using the atomic set_bit()/clear_bit()/test_bit() functions.

Fixes: e17931d1a61d ("batman-adv: introduce capability initialization bitfield")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 4503069e29b5e2262509597fee4058948272d30b..b3e61e575f060ba8dce3d2b7184d2fede28f1e03 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -26,6 +26,7 @@
 #include "bridge_loop_avoidance.h"
 #include "multicast.h"
 
+#include <linux/bitops.h>
 #include <linux/crc32c.h>
 
 /* hash class keys */
@@ -1861,7 +1862,7 @@ void batadv_tt_global_del_orig(struct batadv_priv *bat_priv,
                }
                spin_unlock_bh(list_lock);
        }
-       orig_node->capa_initialized &= ~BATADV_ORIG_CAPA_HAS_TT;
+       clear_bit(BATADV_ORIG_CAPA_HAS_TT, &orig_node->capa_initialized);
 }
 
 static bool batadv_tt_global_to_purge(struct batadv_tt_global_entry *tt_global,
@@ -2821,7 +2822,7 @@ static void _batadv_tt_update_changes(struct batadv_priv *bat_priv,
                                return;
                }
        }
-       orig_node->capa_initialized |= BATADV_ORIG_CAPA_HAS_TT;
+       set_bit(BATADV_ORIG_CAPA_HAS_TT, &orig_node->capa_initialized);
 }
 
 static void batadv_tt_fill_gtable(struct batadv_priv *bat_priv,
@@ -3323,7 +3324,8 @@ static void batadv_tt_update_orig(struct batadv_priv *bat_priv,
        bool has_tt_init;
 
        tt_vlan = (struct batadv_tvlv_tt_vlan_data *)tt_buff;
-       has_tt_init = orig_node->capa_initialized & BATADV_ORIG_CAPA_HAS_TT;
+       has_tt_init = test_bit(BATADV_ORIG_CAPA_HAS_TT,
+                              &orig_node->capa_initialized);
 
        /* orig table not initialised AND first diff is in the OGM OR the ttvn
         * increased by one -> we can apply the attached changes

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 1b0b053ae7294d7b213d3899225eb6bdf8b86816..fdf65b50e3ecd2238e460b416f314bd43b3ccffc 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -259,7 +259,7 @@ struct batadv_orig_node {
        struct hlist_node mcast_want_all_ipv6_node;
 #endif
        unsigned long capabilities;
-       uint8_t capa_initialized;
+       unsigned long capa_initialized;
        atomic_t last_ttvn;
        unsigned char *tt_buff;
        int16_t tt_buff_len;
@@ -300,7 +300,7 @@ struct batadv_orig_node {
 enum batadv_orig_capabilities {
        BATADV_ORIG_CAPA_HAS_DAT,
        BATADV_ORIG_CAPA_HAS_NC,
-       BATADV_ORIG_CAPA_HAS_TT = BIT(2),
+       BATADV_ORIG_CAPA_HAS_TT,
        BATADV_ORIG_CAPA_HAS_MCAST = BIT(3),
 };