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Subject[PATCH 3.19.y-ckt 153/156] batman-adv: Make DAT capability changes atomic
Date
3.19.8-ckt8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>

commit 65d7d46050704bcdb8121ddbf4110bfbf2b38baa 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: 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>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
net/batman-adv/distributed-arp-table.c | 7 ++++---
net/batman-adv/types.h | 4 ++--
2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index b598111..4bbd72e 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -15,6 +15,7 @@
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/

+#include <linux/bitops.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
@@ -422,7 +423,7 @@ 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... */
@@ -682,9 +683,9 @@ 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 8854c05..3d316c8 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -258,7 +258,7 @@ 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;
@@ -298,7 +298,7 @@ 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),
--
1.9.1


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