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mac80211: Avoid filling up mesh preq queue with redundant requests

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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: Pedro Larbig <pedro.larbig@carhs.de>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Javier Cardona 2011-11-03 21:11:10 -07:00 committed by John W. Linville
parent 7e1e386421
commit f3011cf9de
2 changed files with 16 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
net/mac80211/mesh.h
View File

@ -31,6 +31,8 @@
* @MESH_PATH_FIXED: the mesh path has been manually set and should not be
* modified
* @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
* 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_FIXED = BIT(3),
MESH_PATH_RESOLVED = BIT(4),
MESH_PATH_REQ_QUEUED = BIT(5),
};
/**

15
net/mac80211/mesh_hwmp.c
View File

@ -867,9 +867,19 @@ static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
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);
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);
++ifmsh->preq_queue_len;
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;
spin_lock_bh(&mpath->state_lock);
mpath->flags &= ~MESH_PATH_REQ_QUEUED;
if (preq_node->flags & PREQ_Q_F_START) {
if (mpath->flags & MESH_PATH_RESOLVING) {
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);
}
if (skb_queue_len(&mpath->frame_queue) >=
MESH_FRAME_QUEUE_LEN)
if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)
skb_to_free = skb_dequeue(&mpath->frame_queue);
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)) {
++mpath->discovery_retries;
mpath->discovery_timeout *= 2;
mpath->flags &= ~MESH_PATH_REQ_QUEUED;
spin_unlock_bh(&mpath->state_lock);
mesh_queue_preq(mpath, 0);
} else {