[3.19.y-ckt stable] Patch "batman-adv: Make DAT capability changes atomic" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    batman-adv: Make DAT capability changes atomic

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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>From b1f1d512c62b55df1cf77b995be8d54a6b66f6d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing at c0d3.blue>
Date: Tue, 16 Jun 2015 17:10:22 +0200
Subject: batman-adv: Make DAT capability changes atomic
MIME-Version: 1.0
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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 at c0d3.blue>
Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio at meshcoding.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>

Signed-off-by: Kamal Mostafa <kamal at 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