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

[Luis Henriques]

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

    batman-adv: Make TT capability changes atomic

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt18.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 252a64bf4f35e0af5c08d541c80f3c5b438d372e 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 17:10:24 +0200
Subject: batman-adv: Make TT capability changes atomic
MIME-Version: 1.0
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commit ac4eebd48461ec993e7cb614d5afe7df8c72e6b7 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: e17931d1a61d ("batman-adv: introduce capability initialization bitfield")
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>
---
 net/batman-adv/translation-table.c | 8 +++++---
 net/batman-adv/types.h             | 4 ++--
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 4503069e29b5..b3e61e575f06 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -26,6 +26,7 @@
 #include "bridge_loop_avoidance.h"
 #include "multicast.h"

+#include <linux/bitops.h>
 #include <linux/crc32c.h>

 /* hash class keys */
@@ -1861,7 +1862,7 @@ void batadv_tt_global_del_orig(struct batadv_priv *bat_priv,
 		}
 		spin_unlock_bh(list_lock);
 	}
-	orig_node->capa_initialized &= ~BATADV_ORIG_CAPA_HAS_TT;
+	clear_bit(BATADV_ORIG_CAPA_HAS_TT, &orig_node->capa_initialized);
 }

 static bool batadv_tt_global_to_purge(struct batadv_tt_global_entry *tt_global,
@@ -2821,7 +2822,7 @@ static void _batadv_tt_update_changes(struct batadv_priv *bat_priv,
 				return;
 		}
 	}
-	orig_node->capa_initialized |= BATADV_ORIG_CAPA_HAS_TT;
+	set_bit(BATADV_ORIG_CAPA_HAS_TT, &orig_node->capa_initialized);
 }

 static void batadv_tt_fill_gtable(struct batadv_priv *bat_priv,
@@ -3323,7 +3324,8 @@ static void batadv_tt_update_orig(struct batadv_priv *bat_priv,
 	bool has_tt_init;

 	tt_vlan = (struct batadv_tvlv_tt_vlan_data *)tt_buff;
-	has_tt_init = orig_node->capa_initialized & BATADV_ORIG_CAPA_HAS_TT;
+	has_tt_init = test_bit(BATADV_ORIG_CAPA_HAS_TT,
+			       &orig_node->capa_initialized);

 	/* orig table not initialised AND first diff is in the OGM OR the ttvn
 	 * increased by one -> we can apply the attached changes
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 1b0b053ae729..fdf65b50e3ec 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -259,7 +259,7 @@ struct batadv_orig_node {
 	struct hlist_node mcast_want_all_ipv6_node;
 #endif
 	unsigned long capabilities;
-	uint8_t capa_initialized;
+	unsigned long capa_initialized;
 	atomic_t last_ttvn;
 	unsigned char *tt_buff;
 	int16_t tt_buff_len;
@@ -300,7 +300,7 @@ struct batadv_orig_node {
 enum batadv_orig_capabilities {
 	BATADV_ORIG_CAPA_HAS_DAT,
 	BATADV_ORIG_CAPA_HAS_NC,
-	BATADV_ORIG_CAPA_HAS_TT = BIT(2),
+	BATADV_ORIG_CAPA_HAS_TT,
 	BATADV_ORIG_CAPA_HAS_MCAST = BIT(3),
 };