batman-adv: Make NC 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: 3f4841ffb336 ("batman-adv: tvlv - add network coding 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/network-coding.c b/net/batman-adv/network-coding.c
index f0a50f3..4660401 100644 (file)
--- a/net/batman-adv/network-coding.c
+++ b/net/batman-adv/network-coding.c
@@ -19,6 +19,7 @@
 #include "main.h"
 
 #include <linux/atomic.h>
+#include <linux/bitops.h>
 #include <linux/byteorder/generic.h>
 #include <linux/compiler.h>
 #include <linux/debugfs.h>
@@ -134,9 +135,9 @@ static void batadv_nc_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_NC;
+               clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
        else
-               orig->capabilities |= BATADV_ORIG_CAPA_HAS_NC;
+               set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 }
 
 /**
@@ -894,7 +895,7 @@ void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
                goto out;
 
        /* check if orig node is network coding enabled */
-       if (!(orig_node->capabilities & BATADV_ORIG_CAPA_HAS_NC))
+       if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
                goto out;
 
        /* accept ogms from 'good' neighbors and single hop neighbors */

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 29fd625..ed4aec5 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -314,7 +314,7 @@ struct batadv_orig_node {
  */
 enum batadv_orig_capabilities {
        BATADV_ORIG_CAPA_HAS_DAT,
-       BATADV_ORIG_CAPA_HAS_NC = BIT(1),
+       BATADV_ORIG_CAPA_HAS_NC,
        BATADV_ORIG_CAPA_HAS_TT = BIT(2),
        BATADV_ORIG_CAPA_HAS_MCAST = BIT(3),
 };