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Patch "batman-adv: Make MCAST capability changes atomic" has been added to the 4.2-stable tree

PATCH [email protected] 1 participant 1 message Oct 17, 2015

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This is a note to let you know that I've just added the patch titled

batman-adv: Make MCAST capability changes atomic

to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
batman-adv-make-mcast-capability-changes-atomic.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 9c936e3f4c4fad07abb6c082a89508b8f724c88f Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Linus=20L=C3=BCssing?= <[email protected]>
Date: Tue, 16 Jun 2015 17:10:25 +0200
Subject: batman-adv: Make MCAST capability changes atomic
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From: =?UTF-8?q?Linus=20L=C3=BCssing?= <[email protected]>

commit 9c936e3f4c4fad07abb6c082a89508b8f724c88f 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 60432d756cf0 ("batman-adv: Announce new capability via multicast TVLV")
Signed-off-by Linus Lüssing <[email protected]>
Signed-off-by Marek Lindner <[email protected]>
Signed-off-by Antonio Quartulli <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 net/batman-adv/multicast.c |   18 ++++++++++--------
 net/batman-adv/types.h     |    2 +-
 2 files changed, 11 insertions(+), 9 deletions(-)
net/batman-adv/multicast.c +10 -8
@@ -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_handle
 	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 bata
 {
 	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);
net/batman-adv/types.h +1 -1
@@ -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,
 };
 
 /**

Patches currently in stable-queue which might be from [email protected] are

queue-4.2/batman-adv-fix-potential-synchronization-issues-in-mcast-tvlv-handler.patch queue-4.2/batman-adv-make-tt-capability-changes-atomic.patch queue-4.2/batman-adv-make-dat-capability-changes-atomic.patch queue-4.2/batman-adv-make-nc-capability-changes-atomic.patch queue-4.2/batman-adv-fix-potentially-broken-skb-network-header-access.patch queue-4.2/batman-adv-make-mcast-capability-changes-atomic.patch