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batman-adv: Make MCAST 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: 60432d756c ("batman-adv: Announce new capability via multicast TVLV")
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>
This commit is contained in:
Linus Lüssing 2015-06-16 17:10:25 +02:00 committed by Antonio Quartulli
parent ac4eebd484
commit 9c936e3f4c
2 changed files with 11 additions and 9 deletions
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18
net/batman-adv/multicast.c
View File

@ -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>
@ -697,29 +698,30 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
uint8_t mcast_flags = BATADV_NO_FLAGS;
bool orig_initialized;
orig_initialized = orig->capa_initialized & BATADV_ORIG_CAPA_HAS_MCAST;
orig_initialized = test_bit(BATADV_ORIG_CAPA_HAS_MCAST,
&orig->capa_initialized);
/* If mcast support is turned on decrease the disabled mcast node
* counter only if we had increased it for this node before. If this
* is a completely new orig_node no need to decrease the counter.
*/
if (orig_mcast_enabled &&
!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST)) {
!test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities)) {
if (orig_initialized)
atomic_dec(&bat_priv->mcast.num_disabled);
orig->capabilities |= BATADV_ORIG_CAPA_HAS_MCAST;
set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
/* If mcast support is being switched off or if this is an initial
* OGM without mcast support then increase the disabled mcast
* node counter.
*/
} else if (!orig_mcast_enabled &&
(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST ||
(test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities) ||
!orig_initialized)) {
atomic_inc(&bat_priv->mcast.num_disabled);
orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_MCAST;
clear_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
}
orig->capa_initialized |= BATADV_ORIG_CAPA_HAS_MCAST;
set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized);
if (orig_mcast_enabled && tvlv_value &&
(tvlv_value_len >= sizeof(mcast_flags)))
@ -763,8 +765,8 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig)
{
struct batadv_priv *bat_priv = orig->bat_priv;
if (!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST) &&
orig->capa_initialized & BATADV_ORIG_CAPA_HAS_MCAST)
if (!test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities) &&
test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized))
atomic_dec(&bat_priv->mcast.num_disabled);
batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS);

2
net/batman-adv/types.h
View File

@ -316,7 +316,7 @@ enum batadv_orig_capabilities {
BATADV_ORIG_CAPA_HAS_DAT,
BATADV_ORIG_CAPA_HAS_NC,
BATADV_ORIG_CAPA_HAS_TT,
BATADV_ORIG_CAPA_HAS_MCAST = BIT(3),
BATADV_ORIG_CAPA_HAS_MCAST,
};
/**