[PATCH 1/8] batman-adv: Avoid recursive call_rcu for batadv_bla_claim

[PATCH 1/8] batman-adv: Avoid recursive call_rcu for batadv_bla_claim

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

The batadv_claim_free_ref function uses call_rcu to delay the free of the
batadv_bla_claim object until no (already started) rcu_read_lock is enabled
anymore. This makes sure that no context is still trying to access the
object which should be removed. But batadv_bla_claim also contains a
reference to backbone_gw which must be removed.

The reference drop of backbone_gw was done in the call_rcu function
batadv_claim_free_rcu but should actually be done in the
batadv_claim_release function to avoid nested call_rcus. This is important
because rcu_barrier (e.g. batadv_softif_free or batadv_exit) will not
detect the inner call_rcu as relevant for its execution. Otherwise this
barrier will most likely be inserted in the queue before the callback of
the first call_rcu was executed. The caller of rcu_barrier will therefore
continue to run before the inner call_rcu callback finished.

Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/bridge_loop_avoidance.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index d5d71ac96c8a..c24c481b666f 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -127,21 +127,17 @@ batadv_backbone_gw_free_ref(struct batadv_bla_backbone_gw *backbone_gw)
 }
 
 /* finally deinitialize the claim */
-static void batadv_claim_free_rcu(struct rcu_head *rcu)
+static void batadv_claim_release(struct batadv_bla_claim *claim)
 {
-	struct batadv_bla_claim *claim;
-
-	claim = container_of(rcu, struct batadv_bla_claim, rcu);
-
 	batadv_backbone_gw_free_ref(claim->backbone_gw);
-	kfree(claim);
+	kfree_rcu(claim, rcu);
 }
 
 /* free a claim, call claim_free_rcu if its the last reference */
 static void batadv_claim_free_ref(struct batadv_bla_claim *claim)
 {
 	if (atomic_dec_and_test(&claim->refcount))
-		call_rcu(&claim->rcu, batadv_claim_free_rcu);
+		batadv_claim_release(claim);
 }
 
 /**
-- 
2.7.0

[PATCH 2/8] batman-adv: Avoid recursive call_rcu for batadv_nc_node

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

The batadv_nc_node_free_ref function uses call_rcu to delay the free of the
batadv_nc_node object until no (already started) rcu_read_lock is enabled
anymore. This makes sure that no context is still trying to access the
object which should be removed. But batadv_nc_node also contains a
reference to orig_node which must be removed.

The reference drop of orig_node was done in the call_rcu function
batadv_nc_node_free_rcu but should actually be done in the
batadv_nc_node_release function to avoid nested call_rcus. This is
important because rcu_barrier (e.g. batadv_softif_free or batadv_exit) will
not detect the inner call_rcu as relevant for its execution. Otherwise this
barrier will most likely be inserted in the queue before the callback of
the first call_rcu was executed. The caller of rcu_barrier will therefore
continue to run before the inner call_rcu callback finished.

Fixes: d56b1705e28c ("batman-adv: network coding - detect coding nodes and remove these after timeout")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/network-coding.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c
index c98b0ab85449..cc63b44f0d2e 100644
--- a/net/batman-adv/network-coding.c
+++ b/net/batman-adv/network-coding.c
@@ -203,28 +203,25 @@ void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
 }
 
 /**
- * batadv_nc_node_free_rcu - rcu callback to free an nc node and remove
- *  its refcount on the orig_node
- * @rcu: rcu pointer of the nc node
+ * batadv_nc_node_release - release nc_node from lists and queue for free after
+ *  rcu grace period
+ * @nc_node: the nc node to free
  */
-static void batadv_nc_node_free_rcu(struct rcu_head *rcu)
+static void batadv_nc_node_release(struct batadv_nc_node *nc_node)
 {
-	struct batadv_nc_node *nc_node;
-
-	nc_node = container_of(rcu, struct batadv_nc_node, rcu);
 	batadv_orig_node_free_ref(nc_node->orig_node);
-	kfree(nc_node);
+	kfree_rcu(nc_node, rcu);
 }
 
 /**
- * batadv_nc_node_free_ref - decrements the nc node refcounter and possibly
- * frees it
+ * batadv_nc_node_free_ref - decrement the nc node refcounter and possibly
+ *  release it
  * @nc_node: the nc node to free
  */
 static void batadv_nc_node_free_ref(struct batadv_nc_node *nc_node)
 {
 	if (atomic_dec_and_test(&nc_node->refcount))
-		call_rcu(&nc_node->rcu, batadv_nc_node_free_rcu);
+		batadv_nc_node_release(nc_node);
 }
 
 /**
-- 
2.7.0

[PATCH 3/8] batman-adv: Drop immediate batadv_orig_ifinfo free function

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_orig_ifinfo_free_ref.

Fixes: 7351a4822d42 ("batman-adv: split out router from orig_node")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/originator.c | 77 +++++++++++++++++++++++----------------------
 1 file changed, 40 insertions(+), 37 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index ae6d18cafc5a..6929acc1d61a 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -754,19 +754,7 @@ static void batadv_orig_ifinfo_free_rcu(struct rcu_head *rcu)
 }
 
 /**
- * batadv_orig_ifinfo_free_ref - decrement the refcounter and possibly free
- *  the orig_ifinfo (without rcu callback)
- * @orig_ifinfo: the orig_ifinfo object to release
- */
-static void
-batadv_orig_ifinfo_free_ref_now(struct batadv_orig_ifinfo *orig_ifinfo)
-{
-	if (atomic_dec_and_test(&orig_ifinfo->refcount))
-		batadv_orig_ifinfo_free_rcu(&orig_ifinfo->rcu);
-}
-
-/**
- * batadv_orig_ifinfo_free_ref - decrement the refcounter and possibly free
+ * batadv_orig_ifinfo_free_ref - decrement the refcounter and possibly release
  *  the orig_ifinfo
  * @orig_ifinfo: the orig_ifinfo object to release
  */
@@ -776,36 +764,18 @@ void batadv_orig_ifinfo_free_ref(struct batadv_orig_ifinfo *orig_ifinfo)
 		call_rcu(&orig_ifinfo->rcu, batadv_orig_ifinfo_free_rcu);
 }
 
+/**
+ * batadv_orig_node_free_rcu - free the orig_node
+ * @rcu: rcu pointer of the orig_node
+ */
 static void batadv_orig_node_free_rcu(struct rcu_head *rcu)
 {
-	struct hlist_node *node_tmp;
-	struct batadv_neigh_node *neigh_node;
 	struct batadv_orig_node *orig_node;
-	struct batadv_orig_ifinfo *orig_ifinfo;
 
 	orig_node = container_of(rcu, struct batadv_orig_node, rcu);
 
-	spin_lock_bh(&orig_node->neigh_list_lock);
-
-	/* for all neighbors towards this originator ... */
-	hlist_for_each_entry_safe(neigh_node, node_tmp,
-				  &orig_node->neigh_list, list) {
-		hlist_del_rcu(&neigh_node->list);
-		batadv_neigh_node_free_ref_now(neigh_node);
-	}
-
-	hlist_for_each_entry_safe(orig_ifinfo, node_tmp,
-				  &orig_node->ifinfo_list, list) {
-		hlist_del_rcu(&orig_ifinfo->list);
-		batadv_orig_ifinfo_free_ref_now(orig_ifinfo);
-	}
-	spin_unlock_bh(&orig_node->neigh_list_lock);
-
 	batadv_mcast_purge_orig(orig_node);
 
-	/* Free nc_nodes */
-	batadv_nc_purge_orig(orig_node->bat_priv, orig_node, NULL);
-
 	batadv_frag_purge_orig(orig_node, NULL);
 
 	if (orig_node->bat_priv->bat_algo_ops->bat_orig_free)
@@ -816,14 +786,47 @@ static void batadv_orig_node_free_rcu(struct rcu_head *rcu)
 }
 
 /**
+ * batadv_orig_node_release - release orig_node from lists and queue for
+ *  free after rcu grace period
+ * @orig_node: the orig node to free
+ */
+static void batadv_orig_node_release(struct batadv_orig_node *orig_node)
+{
+	struct hlist_node *node_tmp;
+	struct batadv_neigh_node *neigh_node;
+	struct batadv_orig_ifinfo *orig_ifinfo;
+
+	spin_lock_bh(&orig_node->neigh_list_lock);
+
+	/* for all neighbors towards this originator ... */
+	hlist_for_each_entry_safe(neigh_node, node_tmp,
+				  &orig_node->neigh_list, list) {
+		hlist_del_rcu(&neigh_node->list);
+		batadv_neigh_node_free_ref(neigh_node);
+	}
+
+	hlist_for_each_entry_safe(orig_ifinfo, node_tmp,
+				  &orig_node->ifinfo_list, list) {
+		hlist_del_rcu(&orig_ifinfo->list);
+		batadv_orig_ifinfo_free_ref(orig_ifinfo);
+	}
+	spin_unlock_bh(&orig_node->neigh_list_lock);
+
+	/* Free nc_nodes */
+	batadv_nc_purge_orig(orig_node->bat_priv, orig_node, NULL);
+
+	call_rcu(&orig_node->rcu, batadv_orig_node_free_rcu);
+}
+
+/**
  * batadv_orig_node_free_ref - decrement the orig node refcounter and possibly
- * schedule an rcu callback for freeing it
+ *  release it
  * @orig_node: the orig node to free
  */
 void batadv_orig_node_free_ref(struct batadv_orig_node *orig_node)
 {
 	if (atomic_dec_and_test(&orig_node->refcount))
-		call_rcu(&orig_node->rcu, batadv_orig_node_free_rcu);
+		batadv_orig_node_release(orig_node);
 }
 
 /**
-- 
2.7.0

[PATCH 4/8] batman-adv: Drop immediate batadv_neigh_node free function

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_neigh_node_free_ref.

Fixes: 89652331c00f ("batman-adv: split tq information in neigh_node struct")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/originator.c | 33 ++++++++++-----------------------
 1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 6929acc1d61a..78fd4eab2169 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -285,20 +285,8 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
 }
 
 /**
- * batadv_neigh_node_free_ref_now - decrement the neighbors refcounter
- *  and possibly free it (without rcu callback)
- * @neigh_node: neigh neighbor to free
- */
-static void
-batadv_neigh_node_free_ref_now(struct batadv_neigh_node *neigh_node)
-{
-	if (atomic_dec_and_test(&neigh_node->refcount))
-		batadv_neigh_node_free_rcu(&neigh_node->rcu);
-}
-
-/**
  * batadv_neigh_node_free_ref - decrement the neighbors refcounter
- *  and possibly free it
+ *  and possibly release it
  * @neigh_node: neigh neighbor to free
  */
 void batadv_neigh_node_free_ref(struct batadv_neigh_node *neigh_node)
@@ -733,24 +721,23 @@ int batadv_hardif_neigh_seq_print_text(struct seq_file *seq, void *offset)
 }
 
 /**
- * batadv_orig_ifinfo_free_rcu - free the orig_ifinfo object
- * @rcu: rcu pointer of the orig_ifinfo object
+ * batadv_orig_ifinfo_release - release orig_ifinfo from lists and queue for
+ *  free after rcu grace period
+ * @orig_ifinfo: the orig_ifinfo object to release
  */
-static void batadv_orig_ifinfo_free_rcu(struct rcu_head *rcu)
+static void batadv_orig_ifinfo_release(struct batadv_orig_ifinfo *orig_ifinfo)
 {
-	struct batadv_orig_ifinfo *orig_ifinfo;
 	struct batadv_neigh_node *router;
 
-	orig_ifinfo = container_of(rcu, struct batadv_orig_ifinfo, rcu);
-
 	if (orig_ifinfo->if_outgoing != BATADV_IF_DEFAULT)
-		batadv_hardif_free_ref_now(orig_ifinfo->if_outgoing);
+		batadv_hardif_free_ref(orig_ifinfo->if_outgoing);
 
 	/* this is the last reference to this object */
 	router = rcu_dereference_protected(orig_ifinfo->router, true);
 	if (router)
-		batadv_neigh_node_free_ref_now(router);
-	kfree(orig_ifinfo);
+		batadv_neigh_node_free_ref(router);
+
+	kfree_rcu(orig_ifinfo, rcu);
 }
 
 /**
@@ -761,7 +748,7 @@ static void batadv_orig_ifinfo_free_rcu(struct rcu_head *rcu)
 void batadv_orig_ifinfo_free_ref(struct batadv_orig_ifinfo *orig_ifinfo)
 {
 	if (atomic_dec_and_test(&orig_ifinfo->refcount))
-		call_rcu(&orig_ifinfo->rcu, batadv_orig_ifinfo_free_rcu);
+		batadv_orig_ifinfo_release(orig_ifinfo);
 }
 
 /**
-- 
2.7.0

[PATCH 5/8] batman-adv: Drop immediate batadv_hardif_neigh_node free function

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_hardif_neigh_free_ref.

Fixes: cef63419f7db ("batman-adv: add list of unique single hop neighbors per hard-interface")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/originator.c | 46 +++++++++++++--------------------------------
 1 file changed, 13 insertions(+), 33 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 78fd4eab2169..0b7ab38e74fc 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -202,50 +202,30 @@ void batadv_neigh_ifinfo_free_ref(struct batadv_neigh_ifinfo *neigh_ifinfo)
 }
 
 /**
- * batadv_hardif_neigh_free_rcu - free the hardif neigh_node
- * @rcu: rcu pointer of the neigh_node
- */
-static void batadv_hardif_neigh_free_rcu(struct rcu_head *rcu)
-{
-	struct batadv_hardif_neigh_node *hardif_neigh;
-
-	hardif_neigh = container_of(rcu, struct batadv_hardif_neigh_node, rcu);
-
-	batadv_hardif_free_ref_now(hardif_neigh->if_incoming);
-	kfree(hardif_neigh);
-}
-
-/**
- * batadv_hardif_neigh_free_now - decrement the hardif neighbors refcounter
- *  and possibly free it (without rcu callback)
+ * batadv_hardif_neigh_release - release hardif neigh node from lists and
+ *  queue for free after rcu grace period
  * @hardif_neigh: hardif neigh neighbor to free
  */
 static void
-batadv_hardif_neigh_free_now(struct batadv_hardif_neigh_node *hardif_neigh)
+batadv_hardif_neigh_release(struct batadv_hardif_neigh_node *hardif_neigh)
 {
-	if (atomic_dec_and_test(&hardif_neigh->refcount)) {
-		spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
-		hlist_del_init_rcu(&hardif_neigh->list);
-		spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
+	spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
+	hlist_del_init_rcu(&hardif_neigh->list);
+	spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
 
-		batadv_hardif_neigh_free_rcu(&hardif_neigh->rcu);
-	}
+	batadv_hardif_free_ref(hardif_neigh->if_incoming);
+	kfree_rcu(hardif_neigh, rcu);
 }
 
 /**
  * batadv_hardif_neigh_free_ref - decrement the hardif neighbors refcounter
- *  and possibly free it
+ *  and possibly release it
  * @hardif_neigh: hardif neigh neighbor to free
  */
 void batadv_hardif_neigh_free_ref(struct batadv_hardif_neigh_node *hardif_neigh)
 {
-	if (atomic_dec_and_test(&hardif_neigh->refcount)) {
-		spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
-		hlist_del_init_rcu(&hardif_neigh->list);
-		spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
-
-		call_rcu(&hardif_neigh->rcu, batadv_hardif_neigh_free_rcu);
-	}
+	if (atomic_dec_and_test(&hardif_neigh->refcount))
+		batadv_hardif_neigh_release(hardif_neigh);
 }
 
 /**
@@ -272,8 +252,8 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
 					       neigh_node->addr);
 	if (hardif_neigh) {
 		/* batadv_hardif_neigh_get() increases refcount too */
-		batadv_hardif_neigh_free_now(hardif_neigh);
-		batadv_hardif_neigh_free_now(hardif_neigh);
+		batadv_hardif_neigh_free_ref(hardif_neigh);
+		batadv_hardif_neigh_free_ref(hardif_neigh);
 	}
 
 	if (bao->bat_neigh_free)
-- 
2.7.0

[PATCH 6/8] batman-adv: Drop immediate neigh_ifinfo free function

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_neigh_ifinfo_free_ref.

Fixes: 89652331c00f ("batman-adv: split tq information in neigh_node struct")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/originator.c | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 0b7ab38e74fc..f68333586681 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -163,42 +163,28 @@ err:
 }
 
 /**
- * batadv_neigh_ifinfo_free_rcu - free the neigh_ifinfo object
- * @rcu: rcu pointer of the neigh_ifinfo object
- */
-static void batadv_neigh_ifinfo_free_rcu(struct rcu_head *rcu)
-{
-	struct batadv_neigh_ifinfo *neigh_ifinfo;
-
-	neigh_ifinfo = container_of(rcu, struct batadv_neigh_ifinfo, rcu);
-
-	if (neigh_ifinfo->if_outgoing != BATADV_IF_DEFAULT)
-		batadv_hardif_free_ref_now(neigh_ifinfo->if_outgoing);
-
-	kfree(neigh_ifinfo);
-}
-
-/**
- * batadv_neigh_ifinfo_free_now - decrement the refcounter and possibly free
- *  the neigh_ifinfo (without rcu callback)
+ * batadv_neigh_ifinfo_release - release neigh_ifinfo from lists and queue for
+ *  free after rcu grace period
  * @neigh_ifinfo: the neigh_ifinfo object to release
  */
 static void
-batadv_neigh_ifinfo_free_ref_now(struct batadv_neigh_ifinfo *neigh_ifinfo)
+batadv_neigh_ifinfo_release(struct batadv_neigh_ifinfo *neigh_ifinfo)
 {
-	if (atomic_dec_and_test(&neigh_ifinfo->refcount))
-		batadv_neigh_ifinfo_free_rcu(&neigh_ifinfo->rcu);
+	if (neigh_ifinfo->if_outgoing != BATADV_IF_DEFAULT)
+		batadv_hardif_free_ref(neigh_ifinfo->if_outgoing);
+
+	kfree_rcu(neigh_ifinfo, rcu);
 }
 
 /**
- * batadv_neigh_ifinfo_free_ref - decrement the refcounter and possibly free
+ * batadv_neigh_ifinfo_free_ref - decrement the refcounter and possibly release
  *  the neigh_ifinfo
  * @neigh_ifinfo: the neigh_ifinfo object to release
  */
 void batadv_neigh_ifinfo_free_ref(struct batadv_neigh_ifinfo *neigh_ifinfo)
 {
 	if (atomic_dec_and_test(&neigh_ifinfo->refcount))
-		call_rcu(&neigh_ifinfo->rcu, batadv_neigh_ifinfo_free_rcu);
+		batadv_neigh_ifinfo_release(neigh_ifinfo);
 }
 
 /**
@@ -245,7 +231,7 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
 
 	hlist_for_each_entry_safe(neigh_ifinfo, node_tmp,
 				  &neigh_node->ifinfo_list, list) {
-		batadv_neigh_ifinfo_free_ref_now(neigh_ifinfo);
+		batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
 	}
 
 	hardif_neigh = batadv_hardif_neigh_get(neigh_node->if_incoming,
-- 
2.7.0

[PATCH 7/8] batman-adv: Drop immediate batadv_hard_iface free function

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_hardif_free_ref.

Fixes: 89652331c00f ("batman-adv: split tq information in neigh_node struct")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/hard-interface.h | 12 ------------
 net/batman-adv/originator.c     | 15 +++++++--------
 2 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/net/batman-adv/hard-interface.h b/net/batman-adv/hard-interface.h
index 5a31420513e1..7b12ea8ea29d 100644
--- a/net/batman-adv/hard-interface.h
+++ b/net/batman-adv/hard-interface.h
@@ -75,18 +75,6 @@ batadv_hardif_free_ref(struct batadv_hard_iface *hard_iface)
 		call_rcu(&hard_iface->rcu, batadv_hardif_free_rcu);
 }
 
-/**
- * batadv_hardif_free_ref_now - decrement the hard interface refcounter and
- *  possibly free it (without rcu callback)
- * @hard_iface: the hard interface to free
- */
-static inline void
-batadv_hardif_free_ref_now(struct batadv_hard_iface *hard_iface)
-{
-	if (atomic_dec_and_test(&hard_iface->refcount))
-		batadv_hardif_free_rcu(&hard_iface->rcu);
-}
-
 static inline struct batadv_hard_iface *
 batadv_primary_if_get_selected(struct batadv_priv *bat_priv)
 {
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index f68333586681..6fdef842ba2a 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -215,18 +215,17 @@ void batadv_hardif_neigh_free_ref(struct batadv_hardif_neigh_node *hardif_neigh)
 }
 
 /**
- * batadv_neigh_node_free_rcu - free the neigh_node
- * @rcu: rcu pointer of the neigh_node
+ * batadv_neigh_node_release - release neigh_node from lists and queue for
+ *  free after rcu grace period
+ * @neigh_node: neigh neighbor to free
  */
-static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
+static void batadv_neigh_node_release(struct batadv_neigh_node *neigh_node)
 {
 	struct hlist_node *node_tmp;
-	struct batadv_neigh_node *neigh_node;
 	struct batadv_hardif_neigh_node *hardif_neigh;
 	struct batadv_neigh_ifinfo *neigh_ifinfo;
 	struct batadv_algo_ops *bao;
 
-	neigh_node = container_of(rcu, struct batadv_neigh_node, rcu);
 	bao = neigh_node->orig_node->bat_priv->bat_algo_ops;
 
 	hlist_for_each_entry_safe(neigh_ifinfo, node_tmp,
@@ -245,9 +244,9 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
 	if (bao->bat_neigh_free)
 		bao->bat_neigh_free(neigh_node);
 
-	batadv_hardif_free_ref_now(neigh_node->if_incoming);
+	batadv_hardif_free_ref(neigh_node->if_incoming);
 
-	kfree(neigh_node);
+	kfree_rcu(neigh_node, rcu);
 }
 
 /**
@@ -258,7 +257,7 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
 void batadv_neigh_node_free_ref(struct batadv_neigh_node *neigh_node)
 {
 	if (atomic_dec_and_test(&neigh_node->refcount))
-		call_rcu(&neigh_node->rcu, batadv_neigh_node_free_rcu);
+		batadv_neigh_node_release(neigh_node);
 }
 
 /**
-- 
2.7.0

[PATCH 8/8] batman-adv: Drop immediate orig_node free function

[Antonio Quartulli]

From: Sven Eckelmann <sven@narfation.org>

It is not allowed to free the memory of an object which is part of a list
which is protected by rcu-read-side-critical sections without making sure
that no other context is accessing the object anymore. This usually happens
by removing the references to this object and then waiting until the rcu
grace period is over and no one (allowedly) accesses it anymore.

But the _now functions ignore this completely. They free the object
directly even when a different context still tries to access it. This has
to be avoided and thus these functions must be removed and all functions
have to use batadv_orig_node_free_ref.

Fixes: 72822225bd41 ("batman-adv: Fix rcu_barrier() miss due to double call_rcu() in TT code")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
 net/batman-adv/originator.c        | 11 -----------
 net/batman-adv/originator.h        |  1 -
 net/batman-adv/translation-table.c | 28 +++++++++++++---------------
 3 files changed, 13 insertions(+), 27 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 6fdef842ba2a..fe578f75c391 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -781,17 +781,6 @@ void batadv_orig_node_free_ref(struct batadv_orig_node *orig_node)
 		batadv_orig_node_release(orig_node);
 }
 
-/**
- * batadv_orig_node_free_ref_now - decrement the orig node refcounter and
- * possibly free it (without rcu callback)
- * @orig_node: the orig node to free
- */
-void batadv_orig_node_free_ref_now(struct batadv_orig_node *orig_node)
-{
-	if (atomic_dec_and_test(&orig_node->refcount))
-		batadv_orig_node_free_rcu(&orig_node->rcu);
-}
-
 void batadv_originator_free(struct batadv_priv *bat_priv)
 {
 	struct batadv_hashtable *hash = bat_priv->orig_hash;
diff --git a/net/batman-adv/originator.h b/net/batman-adv/originator.h
index 29557753d552..cf0730414ed2 100644
--- a/net/batman-adv/originator.h
+++ b/net/batman-adv/originator.h
@@ -38,7 +38,6 @@ int batadv_originator_init(struct batadv_priv *bat_priv);
 void batadv_originator_free(struct batadv_priv *bat_priv);
 void batadv_purge_orig_ref(struct batadv_priv *bat_priv);
 void batadv_orig_node_free_ref(struct batadv_orig_node *orig_node);
-void batadv_orig_node_free_ref_now(struct batadv_orig_node *orig_node);
 struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
 					      const u8 *addr);
 struct batadv_hardif_neigh_node *
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index a22080c53401..cdfc85fa2743 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -240,20 +240,6 @@ int batadv_tt_global_hash_count(struct batadv_priv *bat_priv,
 	return count;
 }
 
-static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
-{
-	struct batadv_tt_orig_list_entry *orig_entry;
-
-	orig_entry = container_of(rcu, struct batadv_tt_orig_list_entry, rcu);
-
-	/* We are in an rcu callback here, therefore we cannot use
-	 * batadv_orig_node_free_ref() and its call_rcu():
-	 * An rcu_barrier() wouldn't wait for that to finish
-	 */
-	batadv_orig_node_free_ref_now(orig_entry->orig_node);
-	kfree(orig_entry);
-}
-
 /**
  * batadv_tt_local_size_mod - change the size by v of the local table identified
  *  by vid
@@ -349,13 +335,25 @@ static void batadv_tt_global_size_dec(struct batadv_orig_node *orig_node,
 	batadv_tt_global_size_mod(orig_node, vid, -1);
 }
 
+/**
+ * batadv_tt_orig_list_entry_release - release tt orig entry from lists and
+ *  queue for free after rcu grace period
+ * @orig_entry: tt orig entry to be free'd
+ */
+static void
+batadv_tt_orig_list_entry_release(struct batadv_tt_orig_list_entry *orig_entry)
+{
+	batadv_orig_node_free_ref(orig_entry->orig_node);
+	kfree_rcu(orig_entry, rcu);
+}
+
 static void
 batadv_tt_orig_list_entry_free_ref(struct batadv_tt_orig_list_entry *orig_entry)
 {
 	if (!atomic_dec_and_test(&orig_entry->refcount))
 		return;
 
-	call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
+	batadv_tt_orig_list_entry_release(orig_entry);
 }
 
 /**
-- 
2.7.0

Re: pull request [net]: batman-adv 20160117

[David Miller]

From: Antonio Quartulli <a@unstable.cc>
Date: Sun, 17 Jan 2016 13:24:33 +0800

> here you have a bunch of patches intended for net.

Pulled, but you really need to sort something out.

You give really nice detailed, high level, descriptions of
your changes here in this pull request.  It is awesome.

But then you include other text in the merge commit I end
up getting when I pull.  I don't want that _UNLESS_ it's
exactly what you're saying here in this email and therefore
is what I would have put there anyways.

When I did this time is just concatenate them together and therefore
including both things.  But I don't want to have to even think about
this in the future.

Just let me include what you say in this email or put exactly this
text into that merge commit.

Thanks.

Re: pull request [net]: batman-adv 20160117

[Antonio Quartulli]

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On 17/01/16 14:04, David Miller wrote:
> Just let me include what you say in this email or put exactly this
> text into that merge commit.
> 

Thanks for explaining this, David.

Next time I'll put in the git tag the same text as the email (I'll just
drop references to patch numbers because those are not really useful in
the git log).

Cheers,


-- 
Antonio Quartulli


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Re: pull request [net]: batman-adv 20160117

[David Miller]

From: Antonio Quartulli <a@unstable.cc>
Date: Sun, 17 Jan 2016 14:12:32 +0800

> On 17/01/16 14:04, David Miller wrote:
>> Just let me include what you say in this email or put exactly this
>> text into that merge commit.
>> 
> 
> Thanks for explaining this, David.
> 
> Next time I'll put in the git tag the same text as the email (I'll just
> drop references to patch numbers because those are not really useful in
> the git log).

Thanks!