- Operations are now a shared const function block as with most other Linux
  objects

- Introduce wrappers for some optional functions to get consistent behaviour

- Wrap put_char which used to be patched by the tty layer

- Document which functions are needed/optional

- Make put_char report success/fail

- Cache the driver->ops pointer in the tty as tty->ops

- Remove various surplus lock calls we no longer need

- Remove proc_write method as noted by Alexey Dobriyan

- Introduce some missing sanity checks where certain driver/ldisc
  combinations would oops as they didn't check needed methods were present

[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: NAlan Cox <alan@redhat.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

According to one of OOPSes reported by Jann softirq can break
while skb is prepared for netif_rx. The report isn't complete,
so the real reason of the later bug could be different, but
IMHO this locking break in ax_bump is unsafe and unnecessary.
Reported-and-tested-by: NJann Traschewski <jann@gmx.de>
Signed-off-by: NJarek Poplawski <jarkao2@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since hardware header operations are part of the protocol class
not the device instance, make them into a separate object and
save memory.
Signed-off-by: NStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Only the callsign but not the SSID part of an AX.25 address is ASCII
based but Linux by initializes the SSID which should be just a 4-bit
number from ASCII anyway.

Fix that and convert the code to use a shared constant for both default
addresses.  While at it, use the same style for null_ax25_address also.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Various drivers use xmit_lock internally to synchronise with their
transmission routines.  They do so without setting xmit_lock_owner.
This is fine as long as netpoll is not in use.

With netpoll it is possible for deadlocks to occur if xmit_lock_owner
isn't set.  This is because if a printk occurs while xmit_lock is held
and xmit_lock_owner is not set can cause netpoll to attempt to take
xmit_lock recursively.

While it is possible to resolve this by getting netpoll to use
trylock, it is suboptimal because netpoll's sole objective is to
maximise the chance of getting the printk out on the wire.  So
delaying or dropping the message is to be avoided as much as possible.

So the only alternative is to always set xmit_lock_owner.  The
following patch does this by introducing the netif_tx_lock family of
functions that take care of setting/unsetting xmit_lock_owner.

I renamed xmit_lock to _xmit_lock to indicate that it should not be
used directly.  I didn't provide irq versions of the netif_tx_lock
functions since xmit_lock is meant to be a BH-disabling lock.

This is pretty much a straight text substitution except for a small
bug fix in winbond.  It currently uses
netif_stop_queue/spin_unlock_wait to stop transmission.  This is
unsafe as an IRQ can potentially wake up the queue.  So it is safer to
use netif_tx_disable.

The hamradio bits used spin_lock_irq but it is unnecessary as
xmit_lock must never be taken in an IRQ handler.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

MODULE_PARM was actually breaking: recent gcc version optimize them out as
unused.  It's time to replace the last users, which are generally in the
most unloved drivers anyway.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.

This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.

When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.

For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).

Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.

The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.

I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.

Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real.  That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.

Description:

tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification].  It
does now also return the number of chars inserted

There are also

tty_buffer_request_room(tty, len)

which asks for a buffer block of the length requested and returns the space
found.  This improves efficiency with hardware that knows how much to
transfer.

and tty_insert_flip_string_flags(tty, str, flags, len)

to insert a string of characters and flags

For a smart interface the usual code is

    len = tty_request_buffer_room(tty, amount_hardware_says);
    tty_insert_flip_string(tty, buffer_from_card, len);

More description!

At the moment tty buffers are attached directly to the tty.  This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)

I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers.  This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.

So far so good.  Lots of drivers reference tty->flip.*.  Several of them also
call directly and unsafely into function pointers it provides.  This will all
break.  Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.

At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say

 int tty_buffer_request_room(tty, size)

Try and ensure at least size bytes are available, returns actual room (may be
zero).  At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative.  (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space.  The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.

 int tty_insert_flip_char(tty, ch, flag)

As before insert a character if there is room.  Now returns 1 for success, 0
for failure.

 int tty_insert_flip_string(tty, str, len)

Insert a block of non error characters.  Returns the number inserted.

 int tty_prepare_flip_string(tty, strptr, len)

Adjust the buffer to allow len characters to be added.  Returns a buffer
pointer in strptr and the length available.  This allows for hardware that
needs to use functions like insl or mencpy_fromio.
Signed-off-by: NAlan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: NHirokazu Takata <takata@linux-m32r.org>
Signed-off-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NJohn Hawkes <hawkes@sgi.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

With the previous missing-unlock fix the spinlock is dropped only
after the tty->driver->write() call which might sleep.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The unlocking disappeared during commit
5793f4be.
Signed-off-by: NFrancois Romieu <romieu@fr.zoreil.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If .owner isn't set the module can be unloaded even while still active.
Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

SMACK (Stuttgart Modified Amateurradio CRC KISS) is a KISS variant that
uses CRC16 checksums to secure data transfers between the modem and host.
It's also used to communicate over a pty to applications such as Wampes.

Patches for Linux 2.4 by Thomas Osterried DL9SAU, upgraded to the latest
mkiss 2.6 mkiss driver by me.
Signed-off-by: NThomas Osterried DL9SAU <thomas@x-berg.in-berlin.de>
Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>

 drivers/net/hamradio/mkiss.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>

--

 drivers/net/hamradio/mkiss.c |    1 -
 1 files changed, 1 deletion(-)
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

Rename ax25_encapsulate to ax25_hard_header which these days more
accurately describes what the function is supposed to do.
Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Rewrite the mkiss driver to make it SMP-proof following the example of
6pack.c.
Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

Use of time_before() macro, defined at linux/jiffies.h, which deal with
wrapping correctly and are nicer to read.
Signed-off-by: NMarcelo Feitoza Parisi <marcelo@feitoza.com.br>
Signed-off-by: NDomen Puncer <domen@coderock.org>
Signed-off-by: NRalf Baechle DL5RB <ralf@linux-mips.org>

 baycom_epp.c     |    3 ++-
 baycom_par.c     |    3 ++-
 baycom_ser_fdx.c |    3 ++-
 baycom_ser_hdx.c |    3 ++-
 mkiss.c          |    3 ++-
 5 files changed, 10 insertions(+), 5 deletions(-)
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

tty_register_ldisc(N_FOO, NULL) => tty_unregister_ldisc(N_FOO)
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Replacing the open coded equivalents and making ax25 look more like
a linux network protocol, i.e. more similar to inet.
Signed-off-by: NArnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!