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authorLinus Torvalds <torvalds@linux-foundation.org>2012-07-24 10:01:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-07-24 10:01:50 -0700
commit3c4cfadef6a1665d9cd02a543782d03d3e6740c6 (patch)
tree3df72faaacd494d5ac8c9668df4f529b1b5e4457 /Documentation/networking/caif/Linux-CAIF.txt
parente017507f37d5cb8b541df165a824958bc333bec3 (diff)
parent320f5ea0cedc08ef65d67e056bcb9d181386ef2c (diff)
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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking changes from David S Miller: 1) Remove the ipv4 routing cache. Now lookups go directly into the FIB trie and use prebuilt routes cached there. No more garbage collection, no more rDOS attacks on the routing cache. Instead we now get predictable and consistent performance, no matter what the pattern of traffic we service. This has been almost 2 years in the making. Special thanks to Julian Anastasov, Eric Dumazet, Steffen Klassert, and others who have helped along the way. I'm sure that with a change of this magnitude there will be some kind of fallout, but such things ought the be simple to fix at this point. Luckily I'm not European so I'll be around all of August to fix things :-) The major stages of this work here are each fronted by a forced merge commit whose commit message contains a top-level description of the motivations and implementation issues. 2) Pre-demux of established ipv4 TCP sockets, saves a route demux on input. 3) TCP SYN/ACK performance tweaks from Eric Dumazet. 4) Add namespace support for netfilter L4 conntrack helpers, from Gao Feng. 5) Add config mechanism for Energy Efficient Ethernet to ethtool, from Yuval Mintz. 6) Remove quadratic behavior from /proc/net/unix, from Eric Dumazet. 7) Support for connection tracker helpers in userspace, from Pablo Neira Ayuso. 8) Allow userspace driven TX load balancing functions in TEAM driver, from Jiri Pirko. 9) Kill off NLMSG_PUT and RTA_PUT macros, more gross stuff with embedded gotos. 10) TCP Small Queues, essentially minimize the amount of TCP data queued up in the packet scheduler layer. Whereas the existing BQL (Byte Queue Limits) limits the pkt_sched --> netdevice queuing levels, this controls the TCP --> pkt_sched queueing levels. From Eric Dumazet. 11) Reduce the number of get_page/put_page ops done on SKB fragments, from Alexander Duyck. 12) Implement protection against blind resets in TCP (RFC 5961), from Eric Dumazet. 13) Support the client side of TCP Fast Open, basically the ability to send data in the SYN exchange, from Yuchung Cheng. Basically, the sender queues up data with a sendmsg() call using MSG_FASTOPEN, then they do the connect() which emits the queued up fastopen data. 14) Avoid all the problems we get into in TCP when timers or PMTU events hit a locked socket. The TCP Small Queues changes added a tcp_release_cb() that allows us to queue work up to the release_sock() caller, and that's what we use here too. From Eric Dumazet. 15) Zero copy on TX support for TUN driver, from Michael S. Tsirkin. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1870 commits) genetlink: define lockdep_genl_is_held() when CONFIG_LOCKDEP r8169: revert "add byte queue limit support". ipv4: Change rt->rt_iif encoding. net: Make skb->skb_iif always track skb->dev ipv4: Prepare for change of rt->rt_iif encoding. ipv4: Remove all RTCF_DIRECTSRC handliing. ipv4: Really ignore ICMP address requests/replies. decnet: Don't set RTCF_DIRECTSRC. net/ipv4/ip_vti.c: Fix __rcu warnings detected by sparse. ipv4: Remove redundant assignment rds: set correct msg_namelen openvswitch: potential NULL deref in sample() tcp: dont drop MTU reduction indications bnx2x: Add new 57840 device IDs tcp: avoid oops in tcp_metrics and reset tcpm_stamp niu: Change niu_rbr_fill() to use unlikely() to check niu_rbr_add_page() return value niu: Fix to check for dma mapping errors. net: Fix references to out-of-scope variables in put_cmsg_compat() net: ethernet: davinci_emac: add pm_runtime support net: ethernet: davinci_emac: Remove unnecessary #include ...
Diffstat (limited to 'Documentation/networking/caif/Linux-CAIF.txt')
-rw-r--r--Documentation/networking/caif/Linux-CAIF.txt91
1 files changed, 27 insertions, 64 deletions
diff --git a/Documentation/networking/caif/Linux-CAIF.txt b/Documentation/networking/caif/Linux-CAIF.txt
index e52fd62..0aa4bd3 100644
--- a/Documentation/networking/caif/Linux-CAIF.txt
+++ b/Documentation/networking/caif/Linux-CAIF.txt
@@ -19,60 +19,36 @@ and host. Currently, UART and Loopback are available for Linux.
Architecture:
------------
The implementation of CAIF is divided into:
-* CAIF Socket Layer, Kernel API, and Net Device.
+* CAIF Socket Layer and GPRS IP Interface.
* CAIF Core Protocol Implementation
* CAIF Link Layer, implemented as NET devices.
RTNL
!
- ! +------+ +------+ +------+
- ! +------+! +------+! +------+!
- ! ! Sock !! !Kernel!! ! Net !!
- ! ! API !+ ! API !+ ! Dev !+ <- CAIF Client APIs
- ! +------+ +------! +------+
- ! ! ! !
- ! +----------!----------+
- ! +------+ <- CAIF Protocol Implementation
- +-------> ! CAIF !
- ! Core !
- +------+
- +--------!--------+
- ! !
- +------+ +-----+
- ! ! ! TTY ! <- Link Layer (Net Devices)
- +------+ +-----+
-
-
-Using the Kernel API
-----------------------
-The Kernel API is used for accessing CAIF channels from the
-kernel.
-The user of the API has to implement two callbacks for receive
-and control.
-The receive callback gives a CAIF packet as a SKB. The control
-callback will
-notify of channel initialization complete, and flow-on/flow-
-off.
-
-
- struct caif_device caif_dev = {
- .caif_config = {
- .name = "MYDEV"
- .type = CAIF_CHTY_AT
- }
- .receive_cb = my_receive,
- .control_cb = my_control,
- };
- caif_add_device(&caif_dev);
- caif_transmit(&caif_dev, skb);
-
-See the caif_kernel.h for details about the CAIF kernel API.
+ ! +------+ +------+
+ ! +------+! +------+!
+ ! ! IP !! !Socket!!
+ +-------> !interf!+ ! API !+ <- CAIF Client APIs
+ ! +------+ +------!
+ ! ! !
+ ! +-----------+
+ ! !
+ ! +------+ <- CAIF Core Protocol
+ ! ! CAIF !
+ ! ! Core !
+ ! +------+
+ ! +----------!---------+
+ ! ! ! !
+ ! +------+ +-----+ +------+
+ +--> ! HSI ! ! TTY ! ! USB ! <- Link Layer (Net Devices)
+ +------+ +-----+ +------+
+
I M P L E M E N T A T I O N
===========================
-===========================
+
CAIF Core Protocol Layer
=========================================
@@ -88,17 +64,13 @@ The Core CAIF implementation contains:
- Simple implementation of CAIF.
- Layered architecture (a la Streams), each layer in the CAIF
specification is implemented in a separate c-file.
- - Clients must implement PHY layer to access physical HW
- with receive and transmit functions.
- Clients must call configuration function to add PHY layer.
- Clients must implement CAIF layer to consume/produce
CAIF payload with receive and transmit functions.
- Clients must call configuration function to add and connect the
Client layer.
- When receiving / transmitting CAIF Packets (cfpkt), ownership is passed
- to the called function (except for framing layers' receive functions
- or if a transmit function returns an error, in which case the caller
- must free the packet).
+ to the called function (except for framing layers' receive function)
Layered Architecture
--------------------
@@ -109,11 +81,6 @@ Implementation. The support functions include:
CAIF Packet has functions for creating, destroying and adding content
and for adding/extracting header and trailers to protocol packets.
- - CFLST CAIF list implementation.
-
- - CFGLUE CAIF Glue. Contains OS Specifics, such as memory
- allocation, endianness, etc.
-
The CAIF Protocol implementation contains:
- CFCNFG CAIF Configuration layer. Configures the CAIF Protocol
@@ -128,7 +95,7 @@ The CAIF Protocol implementation contains:
control and remote shutdown requests.
- CFVEI CAIF VEI layer. Handles CAIF AT Channels on VEI (Virtual
- External Interface). This layer encodes/decodes VEI frames.
+ External Interface). This layer encodes/decodes VEI frames.
- CFDGML CAIF Datagram layer. Handles CAIF Datagram layer (IP
traffic), encodes/decodes Datagram frames.
@@ -170,7 +137,7 @@ The CAIF Protocol implementation contains:
+---------+ +---------+
! !
+---------+ +---------+
- | | | Serial |
+ | | | Serial |
| | | CFSERL |
+---------+ +---------+
@@ -186,24 +153,20 @@ In this layered approach the following "rules" apply.
layer->dn->transmit(layer->dn, packet);
-Linux Driver Implementation
+CAIF Socket and IP interface
===========================
-Linux GPRS Net Device and CAIF socket are implemented on top of the
-CAIF Core protocol. The Net device and CAIF socket have an instance of
+The IP interface and CAIF socket API are implemented on top of the
+CAIF Core protocol. The IP Interface and CAIF socket have an instance of
'struct cflayer', just like the CAIF Core protocol stack.
Net device and Socket implement the 'receive()' function defined by
'struct cflayer', just like the rest of the CAIF stack. In this way, transmit and
receive of packets is handled as by the rest of the layers: the 'dn->transmit()'
function is called in order to transmit data.
-The layer on top of the CAIF Core implementation is
-sometimes referred to as the "Client layer".
-
-
Configuration of Link Layer
---------------------------
-The Link Layer is implemented as Linux net devices (struct net_device).
+The Link Layer is implemented as Linux network devices (struct net_device).
Payload handling and registration is done using standard Linux mechanisms.
The CAIF Protocol relies on a loss-less link layer without implementing
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