[B.A.T.M.A.N.] [PATCH 05/14] batman-adv: Make NC capability changes atomic

Antonio Quartulli
2015-08-04T16:35:25Z

From: Linus Lüssing <linus.luessing@c0d3.blue>

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>
---
net/batman-adv/network-coding.c | 7 ++++---
net/batman-adv/types.h | 2 +-
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c
index f0a50f3..cfdc80d 100644
--- 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
--- 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),
};
--
2.5.0