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cfg80211/mac80211: add mesh_param "mesh_nolearn" to skip path discovery 

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@narfation.org>
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Linus Lüssing <ll@simonwunderlich.de>
Link: https://lore.kernel.org/r/20200617073034.26149-1-linus.luessing@c0d3.blue
[fix nl80211 policy to range 0/1 only]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
zero-sugar-mainline-defconfig
Linus Lüssing 2020-06-17 09:30:33 +02:00 committed by Johannes Berg
parent 2f1805ea20
commit e3718a6114
8 changed files with 66 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/net/cfg80211.h
View File

@ -1870,6 +1870,11 @@ 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;
@ -1901,6 +1906,7 @@ struct mesh_config {
enum nl80211_mesh_power_mode power_mode;
u16 dot11MeshAwakeWindowDuration;
u32 plink_timeout;
bool dot11MeshNolearn;
};
/**

7
include/uapi/linux/nl80211.h
View File

@ -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,

2
net/mac80211/cfg.c
View File

@ -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;
}

2
net/mac80211/debugfs_netdev.c
View File

@ -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

39
net/mac80211/mesh_hwmp.c
View File

@ -1172,6 +1172,40 @@ int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
return -ENOENT;
}
/**
* mesh_nexthop_lookup_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 PREQ/PREP path discovery.
*
* Returns: 0 if the next hop was found and -ENOENT otherwise.
*/
static int mesh_nexthop_lookup_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_lookup - put the appropriate next hop on a mesh frame. Calling
* this function is considered "using" the associated mpath, so preempt a path
@ -1185,11 +1219,16 @@ int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
int mesh_nexthop_lookup(struct ieee80211_sub_if_data *sdata,
struct sk_buff *skb)
{
struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
struct mesh_path *mpath;
struct sta_info *next_hop;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u8 *target_addr = hdr->addr3;
if (ifmsh->mshcfg.dot11MeshNolearn &&
!mesh_nexthop_lookup_nolearn(sdata, skb))
return 0;
mpath = mesh_path_lookup(sdata, target_addr);
if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
return -ENOENT;

1
net/wireless/mesh.c
View File

@ -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 = {

7
net/wireless/nl80211.c
View File

@ -6885,7 +6885,9 @@ 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);
@ -6943,6 +6945,7 @@ 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] = NLA_POLICY_RANGE(NLA_U8, 0, 1),
};
static const struct nla_policy
@ -7094,6 +7097,8 @@ 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, mask,
NL80211_MESHCONF_NOLEARN, nla_get_u8);
if (mask_out)
*mask_out = mask;

4
net/wireless/trace.h
View File

@ -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) \