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mac80211: don't initiate path discovery when forwarding frame with unknown DA 

We used to initiate a path discovery when receiving a frame for which
there is no forwarding information. To cut down on PREQ spam, just send
a (gated) PERR in response.

Also separate path discovery logic from nexthop querying. This patch
means we no longer queue frames when forwarding, so kill the PERR TX
stuff in discard_frame().

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Thomas Pedersen 2011-11-24 17:15:25 -08:00 committed by John W. Linville
parent dca7e9430c
commit 0cfda8519c
5 changed files with 79 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/mac80211/mesh.h
View File

@ -233,6 +233,8 @@ void ieee80211_mesh_root_setup(struct ieee80211_if_mesh *ifmsh);
/* Mesh paths */
int mesh_nexthop_lookup(struct sk_buff *skb,
struct ieee80211_sub_if_data *sdata);
int mesh_nexthop_resolve(struct sk_buff *skb,
struct ieee80211_sub_if_data *sdata);
void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata);
struct mesh_path *mesh_path_lookup(u8 *dst,
struct ieee80211_sub_if_data *sdata);

111
net/mac80211/mesh_hwmp.c
View File

@ -982,72 +982,97 @@ enddiscovery:
kfree(preq_node);
}
/**
* mesh_nexthop_lookup - put the appropriate next hop on a mesh frame
/* mesh_nexthop_resolve - lookup next hop for given skb and start path
* discovery if no forwarding information is found.
*
* @skb: 802.11 frame to be sent
* @sdata: network subif the frame will be sent through
*
* Returns: 0 if the next hop was found. Nonzero otherwise. If no next hop is
* found, the function will start a path discovery and queue the frame so it is
* sent when the path is resolved. This means the caller must not free the skb
* in this case.
* Returns: 0 if the next hop was found and -ENOENT if the frame was queued.
* skb is freeed here if no mpath could be allocated.
*/
int mesh_nexthop_lookup(struct sk_buff *skb,
struct ieee80211_sub_if_data *sdata)
int mesh_nexthop_resolve(struct sk_buff *skb,
struct ieee80211_sub_if_data *sdata)
{
struct sk_buff *skb_to_free = NULL;
struct mesh_path *mpath;
struct sta_info *next_hop;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct mesh_path *mpath;
struct sk_buff *skb_to_free = NULL;
u8 *target_addr = hdr->addr3;
int err = 0;
rcu_read_lock();
mpath = mesh_path_lookup(target_addr, sdata);
err = mesh_nexthop_lookup(skb, sdata);
if (!err)
goto endlookup;
/* no nexthop found, start resolving */
mpath = mesh_path_lookup(target_addr, sdata);
if (!mpath) {
mesh_path_add(target_addr, sdata);
mpath = mesh_path_lookup(target_addr, sdata);
if (!mpath) {
sdata->u.mesh.mshstats.dropped_frames_no_route++;
mesh_path_discard_frame(skb, sdata);
err = -ENOSPC;
goto endlookup;
}
}
if (mpath->flags & MESH_PATH_ACTIVE) {
if (time_after(jiffies,
mpath->exp_time -
msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
!memcmp(sdata->vif.addr, hdr->addr4, ETH_ALEN) &&
!(mpath->flags & MESH_PATH_RESOLVING) &&
!(mpath->flags & MESH_PATH_FIXED)) {
mesh_queue_preq(mpath,
PREQ_Q_F_START | PREQ_Q_F_REFRESH);
}
next_hop = rcu_dereference(mpath->next_hop);
if (next_hop) {
memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
} else
err = -ENOENT;
} else {
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
if (!(mpath->flags & MESH_PATH_RESOLVING)) {
/* Start discovery only if it is not running yet */
mesh_queue_preq(mpath, PREQ_Q_F_START);
}
if (!(mpath->flags & MESH_PATH_RESOLVING))
mesh_queue_preq(mpath, PREQ_Q_F_START);
if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)
skb_to_free = skb_dequeue(&mpath->frame_queue);
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;
ieee80211_set_qos_hdr(sdata, skb);
skb_queue_tail(&mpath->frame_queue, skb);
if (skb_to_free)
mesh_path_discard_frame(skb_to_free, sdata);
err = -ENOENT;
info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
ieee80211_set_qos_hdr(sdata, skb);
skb_queue_tail(&mpath->frame_queue, skb);
err = -ENOENT;
if (skb_to_free)
mesh_path_discard_frame(skb_to_free, sdata);
endlookup:
rcu_read_unlock();
return err;
}
/**
* mesh_nexthop_lookup - put the appropriate next hop on a mesh frame. Calling
* this function is considered "using" the associated mpath, so preempt a path
* refresh if this mpath expires soon.
*
* @skb: 802.11 frame to be sent
* @sdata: network subif the frame will be sent through
*
* Returns: 0 if the next hop was found. Nonzero otherwise.
*/
int mesh_nexthop_lookup(struct sk_buff *skb,
struct ieee80211_sub_if_data *sdata)
{
struct mesh_path *mpath;
struct sta_info *next_hop;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u8 *target_addr = hdr->addr3;
int err = -ENOENT;
rcu_read_lock();
mpath = mesh_path_lookup(target_addr, sdata);
if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
goto endlookup;
if (time_after(jiffies,
mpath->exp_time -
msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
!memcmp(sdata->vif.addr, hdr->addr4, ETH_ALEN) &&
!(mpath->flags & MESH_PATH_RESOLVING) &&
!(mpath->flags & MESH_PATH_FIXED))
mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
next_hop = rcu_dereference(mpath->next_hop);
if (next_hop) {
memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
err = 0;
}
endlookup:

27
net/mac80211/mesh_pathtbl.c
View File

@ -973,38 +973,11 @@ int mesh_path_send_to_gates(struct mesh_path *mpath)
* @skb: frame to discard
* @sdata: network subif the frame was to be sent through
*
* If the frame was being forwarded from another MP, a PERR frame will be sent
* to the precursor. The precursor's address (i.e. the previous hop) was saved
* in addr1 of the frame-to-be-forwarded, and would only be overwritten once
* the destination is successfully resolved.
*
* Locking: the function must me called within a rcu_read_lock region
*/
void mesh_path_discard_frame(struct sk_buff *skb,
struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct mesh_path *mpath;
u32 sn = 0;
__le16 reason = cpu_to_le16(WLAN_REASON_MESH_PATH_NOFORWARD);
if (memcmp(hdr->addr4, sdata->vif.addr, ETH_ALEN) != 0) {
u8 *ra, *da;
da = hdr->addr3;
ra = hdr->addr2;
rcu_read_lock();
mpath = mesh_path_lookup(da, sdata);
if (mpath) {
spin_lock_bh(&mpath->state_lock);
sn = ++mpath->sn;
spin_unlock_bh(&mpath->state_lock);
}
rcu_read_unlock();
mesh_path_error_tx(sdata->u.mesh.mshcfg.element_ttl, da,
cpu_to_le32(sn), reason, ra, sdata);
}
kfree_skb(skb);
sdata->u.mesh.mshstats.dropped_frames_no_route++;
}

14
net/mac80211/rx.c
View File

@ -1899,6 +1899,7 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
struct ieee80211_local *local = rx->local;
struct ieee80211_sub_if_data *sdata = rx->sdata;
struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
__le16 reason = cpu_to_le16(WLAN_REASON_MESH_PATH_NOFORWARD);
u16 q;
hdr = (struct ieee80211_hdr *) skb->data;
@ -1985,13 +1986,14 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
fwded_mcast);
memcpy(fwd_hdr->addr2, sdata->vif.addr, ETH_ALEN);
} else {
int err;
err = mesh_nexthop_lookup(fwd_skb, sdata);
/* Failed to immediately resolve next hop:
* fwded frame was dropped or will be added
* later to the pending skb queue. */
if (err)
if (mesh_nexthop_lookup(fwd_skb, sdata)) {
/* can't resolve next hop, send a PERR */
mesh_path_error_tx(sdata->u.mesh.mshcfg.element_ttl,
fwd_hdr->addr3, 0, reason,
fwd_hdr->addr2, sdata);
sdata->u.mesh.mshstats.dropped_frames_no_route++;
return RX_DROP_MONITOR;
}
IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.mesh,
fwded_unicast);

2
net/mac80211/tx.c
View File

@ -1464,7 +1464,7 @@ void ieee80211_xmit(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
if (ieee80211_vif_is_mesh(&sdata->vif) &&
ieee80211_is_data(hdr->frame_control) &&
!is_multicast_ether_addr(hdr->addr1))
if (mesh_nexthop_lookup(skb, sdata)) {
if (mesh_nexthop_resolve(skb, sdata)) {
/* skb queued: don't free */
rcu_read_unlock();
return;