Commit dbf498fb authored by Javier Cardona's avatar Javier Cardona Committed by John W. Linville
Browse files

mac80211: Implement mesh synchronization framework 



This patch adds MBSS extensible synchronization framework (Sec.
13.13.2 of IEEE Std. 802.11-2012).

The framework is implemented via an ops table which defines the
following functions:

    rx_bcn_presp() - this is called every time a mesh beacon is
received.
    adjust_tbtt() - this is called immediately before a beacon is about
to be transmitted.

The default neighbor offset synchronization defined in the standard is
implemented.  We also provide template functions for vendor specific
methods.

When neighbor offset synchronization is active (which is the default)
mesh neighbors in the same MBSS will track timing offsets to each other
and compensate clock drift.

In our tests we observed that this mesh synchronization implementation
successfully corrected drifts between stations of ~2PPM while
introducing a jitter of ~20us.

It is also possible to test this framework on mac80211_hwsim simulated
phys to see how it behaves under different topologies, over poor links,
etc.

Signed-off-by: default avatarMarco Porsch <marco.porsch@s2005.tu-chemnitz.de>
Signed-off-by: default avatarPavel Zubarev <pavel.zubarev@gmail.com>
Signed-off-by: default avatarJavier Cardona <javier@cozybit.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 9bdd3a6b

include/linux/ieee80211.h

+12 −0
Original line number Diff line number Diff line
@@ -1438,6 +1438,18 @@ enum ieee80211_tdls_actioncode { 
/* TDLS specific payload type in the LLC/SNAP header */

#define WLAN_TDLS_SNAP_RFTYPE	0x2



/**

 * enum - mesh synchronization method identifier

 *

 * @IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET: the default synchronization method

 * @IEEE80211_SYNC_METHOD_VENDOR: a vendor specific synchronization method

 * that will be specified in a vendor specific information element

 */

enum {

	IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET = 1,

	IEEE80211_SYNC_METHOD_VENDOR = 255,

};



/**

 * enum - mesh path selection protocol identifier

 *

net/mac80211/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -225,6 +225,17 @@ config MAC80211_VERBOSE_MHWMP_DEBUG 


	  Do not select this option.



config MAC80211_VERBOSE_MESH_SYNC_DEBUG

	bool "Verbose mesh mesh synchronization debugging"

	depends on MAC80211_DEBUG_MENU

	depends on MAC80211_MESH

	---help---

	  Selecting this option causes mac80211 to print out very verbose mesh

	  synchronization debugging messages (when mac80211 is taking part in a

	  mesh network).



	  Do not select this option.



config MAC80211_VERBOSE_TDLS_DEBUG

	bool "Verbose TDLS debugging"

	depends on MAC80211_DEBUG_MENU

net/mac80211/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -38,7 +38,8 @@ mac80211-$(CONFIG_MAC80211_MESH) += \ 
	mesh.o \

	mesh_pathtbl.o \

	mesh_plink.o \

	mesh_hwmp.o

	mesh_hwmp.o \

	mesh_sync.o



mac80211-$(CONFIG_PM) += pm.o

net/mac80211/debugfs_sta.c

+3 −2
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ static ssize_t sta_flags_read(struct file *file, char __user *userbuf, 
	test_sta_flag(sta, WLAN_STA_##flg) ? #flg "\n" : ""



	int res = scnprintf(buf, sizeof(buf),

			    "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",

			    "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",

			    TEST(AUTH), TEST(ASSOC), TEST(PS_STA),

			    TEST(PS_DRIVER), TEST(AUTHORIZED),

			    TEST(SHORT_PREAMBLE),
@@ -71,7 +71,8 @@ static ssize_t sta_flags_read(struct file *file, char __user *userbuf, 
			    TEST(MFP), TEST(BLOCK_BA), TEST(PSPOLL),

			    TEST(UAPSD), TEST(SP), TEST(TDLS_PEER),

			    TEST(TDLS_PEER_AUTH), TEST(4ADDR_EVENT),

			    TEST(INSERTED), TEST(RATE_CONTROL));

			    TEST(INSERTED), TEST(RATE_CONTROL),

			    TEST(TOFFSET_KNOWN));

#undef TEST

	return simple_read_from_buffer(userbuf, count, ppos, buf, res);

}

net/mac80211/ieee80211_i.h

+23 −0
Original line number Diff line number Diff line
@@ -554,6 +554,24 @@ struct ieee80211_if_ibss { 
	} state;

};



/**

 * struct ieee80211_mesh_sync_ops - Extensible synchronization framework interface

 *

 * these declarations define the interface, which enables

 * vendor-specific mesh synchronization

 *

 */

struct ieee802_11_elems;

struct ieee80211_mesh_sync_ops {

	void (*rx_bcn_presp)(struct ieee80211_sub_if_data *sdata,

			     u16 stype,

			     struct ieee80211_mgmt *mgmt,

			     struct ieee802_11_elems *elems,

			     struct ieee80211_rx_status *rx_status);

	void (*adjust_tbtt)(struct ieee80211_sub_if_data *sdata);

	/* add other framework functions here */

};



struct ieee80211_if_mesh {

	struct timer_list housekeeping_timer;

	struct timer_list mesh_path_timer;
@@ -602,6 +620,11 @@ struct ieee80211_if_mesh { 
		IEEE80211_MESH_SEC_AUTHED = 0x1,

		IEEE80211_MESH_SEC_SECURED = 0x2,

	} security;

	/* Extensible Synchronization Framework */

	struct ieee80211_mesh_sync_ops *sync_ops;

	s64 sync_offset_clockdrift_max;

	spinlock_t sync_offset_lock;

	bool adjusting_tbtt;

};



#ifdef CONFIG_MAC80211_MESH

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