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Commit f3011cf9 authored by Javier Cardona's avatar Javier Cardona Committed by John W. Linville
Browse files

mac80211: Avoid filling up mesh preq queue with redundant requests 



Don't accept redundant PREQs for a given destination. This fixes a
problem under high load:

kernel: [20386.250913] mesh_queue_preq: 235 callbacks suppressed
kernel: [20386.253335] Mesh HWMP (mesh0): PREQ node queue full
kernel: [20386.253352] Mesh HWMP (mesh0): PREQ node queue full
(...)

The 802.11s protocol has a provision to limit the rate of path requests
(PREQs) are transmitted (dot11MeshHWMPpreqMinInterval) but there was no
limit on the rate at which PREQs were being queued up.  There is a valid
reason for queuing PREQs: this way we can even out PREQ bursts.  But
queueing multiple PREQs for the same destination is useless.

Reported-by: default avatarPedro Larbig <pedro.larbig@carhs.de>
Signed-off-by: default avatarJavier Cardona <javier@cozybit.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 7e1e3864

net/mac80211/mesh.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -31,6 +31,8 @@ 
 * @MESH_PATH_FIXED: the mesh path has been manually set and should not be

 * @MESH_PATH_FIXED: the mesh path has been manually set and should not be

 * 	modified

 * 	modified

 * @MESH_PATH_RESOLVED: the mesh path can has been resolved

 * @MESH_PATH_RESOLVED: the mesh path can has been resolved

 * @MESH_PATH_REQ_QUEUED: there is an unsent path request for this destination

 * already queued up, waiting for the discovery process to start.

 *

 *

 * MESH_PATH_RESOLVED is used by the mesh path timer to

 * MESH_PATH_RESOLVED is used by the mesh path timer to

 * decide when to stop or cancel the mesh path discovery.

 * decide when to stop or cancel the mesh path discovery.
@@ -41,6 +43,7 @@ enum mesh_path_flags { 
	MESH_PATH_SN_VALID =	BIT(2),

	MESH_PATH_SN_VALID =	BIT(2),

	MESH_PATH_FIXED	=	BIT(3),

	MESH_PATH_FIXED	=	BIT(3),

	MESH_PATH_RESOLVED =	BIT(4),

	MESH_PATH_RESOLVED =	BIT(4),

	MESH_PATH_REQ_QUEUED =	BIT(5),

};

};





/**

/**

net/mac80211/mesh_hwmp.c

+13 −2
Original line number Original line Diff line number Diff line
@@ -867,9 +867,19 @@ static void mesh_queue_preq(struct mesh_path *mpath, u8 flags) 
		return;

		return;

	}

	}





	spin_lock_bh(&mpath->state_lock);

	if (mpath->flags & MESH_PATH_REQ_QUEUED) {

		spin_unlock_bh(&mpath->state_lock);

		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);

		return;

	}



	memcpy(preq_node->dst, mpath->dst, ETH_ALEN);

	memcpy(preq_node->dst, mpath->dst, ETH_ALEN);

	preq_node->flags = flags;

	preq_node->flags = flags;





	mpath->flags |= MESH_PATH_REQ_QUEUED;

	spin_unlock_bh(&mpath->state_lock);



	list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);

	list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);

	++ifmsh->preq_queue_len;

	++ifmsh->preq_queue_len;

	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);

	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
@@ -921,6 +931,7 @@ void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata) 
		goto enddiscovery;

		goto enddiscovery;





	spin_lock_bh(&mpath->state_lock);

	spin_lock_bh(&mpath->state_lock);

	mpath->flags &= ~MESH_PATH_REQ_QUEUED;

	if (preq_node->flags & PREQ_Q_F_START) {

	if (preq_node->flags & PREQ_Q_F_START) {

		if (mpath->flags & MESH_PATH_RESOLVING) {

		if (mpath->flags & MESH_PATH_RESOLVING) {

			spin_unlock_bh(&mpath->state_lock);

			spin_unlock_bh(&mpath->state_lock);
@@ -1028,8 +1039,7 @@ int mesh_nexthop_lookup(struct sk_buff *skb, 
			mesh_queue_preq(mpath, PREQ_Q_F_START);

			mesh_queue_preq(mpath, PREQ_Q_F_START);

		}

		}





		if (skb_queue_len(&mpath->frame_queue) >=

		if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)

				MESH_FRAME_QUEUE_LEN)

			skb_to_free = skb_dequeue(&mpath->frame_queue);

			skb_to_free = skb_dequeue(&mpath->frame_queue);





		info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;

		info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
@@ -1061,6 +1071,7 @@ void mesh_path_timer(unsigned long data) 
	} else if (mpath->discovery_retries < max_preq_retries(sdata)) {

	} else if (mpath->discovery_retries < max_preq_retries(sdata)) {

		++mpath->discovery_retries;

		++mpath->discovery_retries;

		mpath->discovery_timeout *= 2;

		mpath->discovery_timeout *= 2;

		mpath->flags &= ~MESH_PATH_REQ_QUEUED;

		spin_unlock_bh(&mpath->state_lock);

		spin_unlock_bh(&mpath->state_lock);

		mesh_queue_preq(mpath, 0);

		mesh_queue_preq(mpath, 0);

	} else {

	} else {