From: Linus Lüssing <ll@xxxxxxxxxxxxxxxxxx>
Currently, before being able to forward a packet between two 802.11s
nodes, both a PLINK handshake is performed upon receiving a beacon and
then later a PREQ/PREP exchange for path discovery is performed on
demand upon receiving a data frame to forward.
When running a mesh protocol on top of an 802.11s interface, like
batman-adv, we do not need the multi-hop mesh routing capabilities of
802.11s and usually set mesh_fwding=0. However, even with mesh_fwding=0
the PREQ/PREP path discovery is still performed on demand. Even though
in this scenario the next hop PREQ/PREP will determine is always the
direct 11s neighbor node.
The new mesh_nolearn parameter allows to skip the PREQ/PREP exchange in
this scenario, leading to a reduced delay, reduced packet buffering and
simplifies HWMP in general.
mesh_nolearn is still rather conservative in that if the packet destination
is not a direct 11s neighbor, it will fall back to PREQ/PREP path
discovery.
For normal, multi-hop 802.11s mesh routing it is usually not advisable
to enable mesh_nolearn as a transmission to a direct but distant neighbor
might be worse than reaching that same node via a more robust /
higher throughput etc. multi-hop path.
Cc: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Cc: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Lüssing <ll@xxxxxxxxxxxxxxxxxx>
---
include/net/cfg80211.h | 6 ++++++
include/uapi/linux/nl80211.h | 7 +++++++
net/mac80211/cfg.c | 2 ++
net/mac80211/debugfs_netdev.c | 2 ++
net/mac80211/mesh_hwmp.c | 39 +++++++++++++++++++++++++++++++++++
net/wireless/mesh.c | 1 +
net/wireless/nl80211.c | 8 ++++++-
net/wireless/trace.h | 4 +++-
8 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index fc7e8807838d..5ffb35592a23 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1853,6 +1853,11 @@ struct bss_parameters {
* connected to a mesh gate in mesh formation info. If false, the
* value in mesh formation is determined by the presence of root paths
* in the mesh path table
+ * @dot11MeshNolearn: Try to avoid multi-hop path discovery (e.g. PREQ/PREP
+ * for HWMP) if the destination is a direct neighbor. Note that this might
+ * not be the optimal decision as a multi-hop route might be better. So
+ * if using this setting you will likely also want to disable
+ * dot11MeshForwarding and use another mesh routing protocol on top.
*/
struct mesh_config {
u16 dot11MeshRetryTimeout;
@@ -1884,6 +1889,7 @@ struct mesh_config {
enum nl80211_mesh_power_mode power_mode;
u16 dot11MeshAwakeWindowDuration;
u32 plink_timeout;
+ bool dot11MeshNolearn;
};
/**
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 4e6339ab1fce..f6560bb9644c 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -4236,6 +4236,12 @@ enum nl80211_mesh_power_mode {
* field. If left unset then the mesh formation field will only
* advertise such if there is an active root mesh path.
*
+ * @NL80211_MESHCONF_NOLEARN: Try to avoid multi-hop path discovery (e.g.
+ * PREQ/PREP for HWMP) if the destination is a direct neighbor. Note that
+ * this might not be the optimal decision as a multi-hop route might be
+ * better. So if using this setting you will likely also want to disable
+ * dot11MeshForwarding and use another mesh routing protocol on top.
+ *
* @__NL80211_MESHCONF_ATTR_AFTER_LAST: internal use
*/
enum nl80211_meshconf_params {
@@ -4269,6 +4275,7 @@ enum nl80211_meshconf_params {
NL80211_MESHCONF_AWAKE_WINDOW,
NL80211_MESHCONF_PLINK_TIMEOUT,
NL80211_MESHCONF_CONNECTED_TO_GATE,
+ NL80211_MESHCONF_NOLEARN,
/* keep last */
__NL80211_MESHCONF_ATTR_AFTER_LAST,
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 9b360544ad6f..f48e095e912a 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2126,6 +2126,8 @@ static int ieee80211_update_mesh_config(struct wiphy *wiphy,
if (_chg_mesh_attr(NL80211_MESHCONF_CONNECTED_TO_GATE, mask))
conf->dot11MeshConnectedToMeshGate =
nconf->dot11MeshConnectedToMeshGate;
+ if (_chg_mesh_attr(NL80211_MESHCONF_NOLEARN, mask))
+ conf->dot11MeshNolearn = nconf->dot11MeshNolearn;
ieee80211_mbss_info_change_notify(sdata, BSS_CHANGED_BEACON);
return 0;
}
diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index d7e955127d5c..09eab2c3f380 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -638,6 +638,7 @@ IEEE80211_IF_FILE(dot11MeshAwakeWindowDuration,
u.mesh.mshcfg.dot11MeshAwakeWindowDuration, DEC);
IEEE80211_IF_FILE(dot11MeshConnectedToMeshGate,
u.mesh.mshcfg.dot11MeshConnectedToMeshGate, DEC);
+IEEE80211_IF_FILE(dot11MeshNolearn, u.mesh.mshcfg.dot11MeshNolearn, DEC);
#endif
#define DEBUGFS_ADD_MODE(name, mode) \
@@ -762,6 +763,7 @@ static void add_mesh_config(struct ieee80211_sub_if_data *sdata)
MESHPARAMS_ADD(power_mode);
MESHPARAMS_ADD(dot11MeshAwakeWindowDuration);
MESHPARAMS_ADD(dot11MeshConnectedToMeshGate);
+ MESHPARAMS_ADD(dot11MeshNolearn);
#undef MESHPARAMS_ADD
}
#endif
diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index aa5150929996..cbf94c0b408f 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -1117,6 +1117,40 @@ void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
kfree(preq_node);
}
+/**
+ * mesh_nexthop_resolve_nolearn - try to set next hop without path discovery
+ * @skb: 802.11 frame to be sent
+ * @sdata: network subif the frame will be sent through
+ *
+ * Check if the meshDA (addr3) of a unicast frame is a direct neighbor.
+ * And if so, set the RA (addr1) to it to transmit to this node directly,
+ * avoiding PREP/PREP path discovery.
+ *
+ * Returns: 0 if the next hop was found and -ENOENT otherwise.
+ */
+static int mesh_nexthop_resolve_nolearn(struct ieee80211_sub_if_data *sdata,
+ struct sk_buff *skb)
+{
+ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+ struct sta_info *sta;
+
+ if (is_multicast_ether_addr(hdr->addr1))
+ return -ENOENT;
+
+ rcu_read_lock();
+ sta = sta_info_get(sdata, hdr->addr3);
+
+ if (!sta || sta->mesh->plink_state != NL80211_PLINK_ESTAB) {
+ rcu_read_unlock();
+ return -ENOENT;
+ }
+ rcu_read_unlock();
+
+ memcpy(hdr->addr1, hdr->addr3, ETH_ALEN);
+ memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
+ return 0;
+}
+
/**
* mesh_nexthop_resolve - lookup next hop; conditionally start path discovery
*
@@ -1132,6 +1166,7 @@ void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
struct sk_buff *skb)
{
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct mesh_path *mpath;
@@ -1146,6 +1181,10 @@ int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
if (info->control.flags & IEEE80211_TX_CTRL_SKIP_MPATH_LOOKUP)
return 0;
+ if (ifmsh->mshcfg.dot11MeshNolearn &&
+ !mesh_nexthop_resolve_nolearn(sdata, skb))
+ return 0;
+
if (!mesh_nexthop_lookup(sdata, skb))
return 0;
diff --git a/net/wireless/mesh.c b/net/wireless/mesh.c
index eac5aa1419fc..e4e363138279 100644
--- a/net/wireless/mesh.c
+++ b/net/wireless/mesh.c
@@ -78,6 +78,7 @@ const struct mesh_config default_mesh_config = {
.power_mode = NL80211_MESH_POWER_ACTIVE,
.dot11MeshAwakeWindowDuration = MESH_DEFAULT_AWAKE_WINDOW,
.plink_timeout = MESH_DEFAULT_PLINK_TIMEOUT,
+ .dot11MeshNolearn = false,
};
const struct mesh_setup default_mesh_setup = {
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 263ae395ad44..b0b7f110064f 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -6884,7 +6884,9 @@ static int nl80211_get_mesh_config(struct sk_buff *skb,
nla_put_u32(msg, NL80211_MESHCONF_PLINK_TIMEOUT,
cur_params.plink_timeout) ||
nla_put_u8(msg, NL80211_MESHCONF_CONNECTED_TO_GATE,
- cur_params.dot11MeshConnectedToMeshGate))
+ cur_params.dot11MeshConnectedToMeshGate) ||
+ nla_put_u8(msg, NL80211_MESHCONF_NOLEARN,
+ cur_params.dot11MeshNolearn))
goto nla_put_failure;
nla_nest_end(msg, pinfoattr);
genlmsg_end(msg, hdr);
@@ -6942,6 +6944,7 @@ nl80211_meshconf_params_policy[NL80211_MESHCONF_ATTR_MAX+1] = {
[NL80211_MESHCONF_AWAKE_WINDOW] = { .type = NLA_U16 },
[NL80211_MESHCONF_PLINK_TIMEOUT] = { .type = NLA_U32 },
[NL80211_MESHCONF_CONNECTED_TO_GATE] = NLA_POLICY_RANGE(NLA_U8, 0, 1),
+ [NL80211_MESHCONF_NOLEARN] = { .type = NLA_U8 },
};
static const struct nla_policy
@@ -7093,6 +7096,9 @@ do { \
NL80211_MESHCONF_AWAKE_WINDOW, nla_get_u16);
FILL_IN_MESH_PARAM_IF_SET(tb, cfg, plink_timeout, mask,
NL80211_MESHCONF_PLINK_TIMEOUT, nla_get_u32);
+ FILL_IN_MESH_PARAM_IF_SET(tb, cfg, dot11MeshNolearn, 0, 1,
+ mask, NL80211_MESHCONF_NOLEARN,
+ nl80211_check_bool);
if (mask_out)
*mask_out = mask;
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index b23cab016521..6e218a0acd4e 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -68,7 +68,8 @@
__field(u16, ht_opmode) \
__field(u32, dot11MeshHWMPactivePathToRootTimeout) \
__field(u16, dot11MeshHWMProotInterval) \
- __field(u16, dot11MeshHWMPconfirmationInterval)
+ __field(u16, dot11MeshHWMPconfirmationInterval) \
+ __field(bool, dot11MeshNolearn)
#define MESH_CFG_ASSIGN \
do { \
__entry->dot11MeshRetryTimeout = conf->dot11MeshRetryTimeout; \
@@ -109,6 +110,7 @@
conf->dot11MeshHWMProotInterval; \
__entry->dot11MeshHWMPconfirmationInterval = \
conf->dot11MeshHWMPconfirmationInterval; \
+ __entry->dot11MeshNolearn = conf->dot11MeshNolearn; \
} while (0)
#define CHAN_ENTRY __field(enum nl80211_band, band) \
--
2.27.0
