batman-adv: Make DAT capability changes atomic

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: 17cf0ea455f1 ("batman-adv: tvlv - add distributed arp table container")
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>

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index fb54e6a..1cfba20 100644 (file)
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -19,6 +19,7 @@
 #include "main.h"
 
 #include <linux/atomic.h>
+#include <linux/bitops.h>
 #include <linux/byteorder/generic.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
@@ -453,7 +454,7 @@ static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
        int j;
 
        /* check if orig node candidate is running DAT */
-       if (!(candidate->capabilities & BATADV_ORIG_CAPA_HAS_DAT))
+       if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
                goto out;
 
        /* Check if this node has already been selected... */
@@ -713,9 +714,9 @@ static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
                                           uint16_t tvlv_value_len)
 {
        if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
-               orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_DAT;
+               clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
        else
-               orig->capabilities |= BATADV_ORIG_CAPA_HAS_DAT;
+               set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
 }
 
 /**

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 67d6348..29fd625 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -273,7 +273,7 @@ struct batadv_orig_node {
        struct hlist_node mcast_want_all_ipv4_node;
        struct hlist_node mcast_want_all_ipv6_node;
 #endif
-       uint8_t capabilities;
+       unsigned long capabilities;
        uint8_t capa_initialized;
        atomic_t last_ttvn;
        unsigned char *tt_buff;
@@ -313,7 +313,7 @@ struct batadv_orig_node {
  *  (= orig node announces a tvlv of type BATADV_TVLV_MCAST)
  */
 enum batadv_orig_capabilities {
-       BATADV_ORIG_CAPA_HAS_DAT = BIT(0),
+       BATADV_ORIG_CAPA_HAS_DAT,
        BATADV_ORIG_CAPA_HAS_NC = BIT(1),
        BATADV_ORIG_CAPA_HAS_TT = BIT(2),
        BATADV_ORIG_CAPA_HAS_MCAST = BIT(3),