Instead of using chip->release() we can achieve the same
using a simple wrapper for free_irq().
We have already um_request_irq(), so um_free_irq() is the perfect
counterpart.
Signed-off-by: NRichard Weinberger <richard@nod.at>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

... and switch chan_interrupt() to directly calling close_one_chan(),
so we can lose delay_free_irq argument of close_chan() as well.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

... since chan_interrupt() might schedule it if there's too much
incoming data.  Kill task argument of chan_interrupt(), while
we are at it - it's always &line->task.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

put references to in and out chans associated with line into
explicit struct chan * fields in it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

Pull parse_chan_pair() call into setup_one_line(), under the mutex.
We really don't want open() to succeed before parse_chan_pair() had
been done (or after it has failed, BTW).  We also want "remove con<n>"
to free irqs, etc., same as "config con<n>=none".
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

delay_free_irq is always 0 for those...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NRichard Weinberger <richard@nod.at>

GCC 4.6's -Wunused-but-set-variable found some dead code.
Signed-off-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When I use OpenSUSE-11.2 on UML (> 2.6.25)
I get lots of such errors:

Registering fd 1 twice
Irqs : 3, 3
Ids : 0x09cb41a0, 0x09cb4120
------------[ cut here ]------------
WARNING: at kernel/irq/manage.c:896 __free_irq+0x79/0x11a()
Trying to free already-free IRQ 3
Modules linked in:
09dadc6c:  [<081b2edb>] dump_stack+0x1c/0x20
09dadc84:  [<080716da>] warn_slowpath_common+0x49/0x77
09dadc9c:  [<08071772>] warn_slowpath_fmt+0x26/0x2a
09dadcb4:  [<08094e08>] __free_irq+0x79/0x11a
09dadce4:  [<08094ed6>] free_irq+0x2d/0x49
09dadcf4:  [<0805b4bc>] close_one_chan+0x70/0x9c
09dadd0c:  [<0805b833>] close_chan+0x17/0x22
09dadd1c:  [<0805bdda>] enable_chan+0x70/0x7c
09dadd3c:  [<0805cbb7>] line_open+0x34/0x9f
09dadd54:  [<0805b21e>] con_open+0x13/0x35
09dadd6c:  [<0814dc89>] tty_open+0x285/0x384
09dadda0:  [<080b754e>] chrdev_open+0xe0/0xf9
09daddc0:  [<080b3fb2>] __dentry_open+0xf3/0x1e2
09dadde4:  [<080b4142>] nameidata_to_filp+0x35/0x49
09daddfc:  [<080bd270>] do_last+0x409/0x50e
09dade28:  [<080bea04>] do_filp_open+0x175/0x446
09dadecc:  [<080b3d89>] do_sys_open+0x4a/0x128
09dadf04:  [<080b3ea2>] sys_open+0x19/0x21
09dadf28:  [<0805ab5a>] handle_syscall+0x7a/0x98
09dadf78:  [<08068441>] userspace+0x2c9/0x370
09dadfe0:  [<08058bb3>] fork_handler+0x53/0x5b
09dadffc:  [<00766564>] 0x766564

---[ end trace 9ebc1094aaf4bded ]---

This patch fixes the issue.
Signed-off-by: NRichard Weinberger <richard@nod.at>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/chan_kern.c::chan_out_fd() is not used by anyone.  Remove it.
Acked-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NWANG Cong <wangcong@zeuux.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/chan_kern.c::open_chan() can become static.
Acked-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NWANG Cong <wangcong@zeuux.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The previous console cleanup patch switched generic_read and generic_write
from calling os_{read,write}_file to calling read and write directly.  Because
the calling convention is different, they now need to get any error from errno
rather than the return value.  I did this for generic_read, but forgot about
generic_write.

While chasing some output corruption, I noticed that line_write was
unnecessarily calling flush_buffer, and deleted it.  I don't understand why,
but the corruption disappeared.  This is unneeded because there already is a
perfectly good mechanism for finding out when the host output device has some
room to write data - there is an interrupt that comes in when writes can
happen again.  line_write calling flush_buffer seemed to just be an attempt to
opportunistically get some data out to the host.

I also made write_chan short-circuit calling into the host-level code for
zero-length writes.  Calling libc write with a length of zero conflated write
not being able to write anything with asking it not to write anything.  Better
to just cut it off as soon as possible.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This does a lot of cleanup on the UML console system.  This patch should be
entirely non-functional.

The tidying is as follows:
	header cleanups - the includes should be closer to minimal and complete
	all printks now have a severity
	lots of style fixes
	fd_close is restructured a little in order to reduce the nesting
	some functions were calling the os_* wrappers when they can
call libc directly
	port_accept had a unnecessary variable
	it also tested a pid unecessarily before killing it
	some functions were made static
	xterm_free is gone, as it was identical to generic_free
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move some code from a kernelspace file to a userspace file where it fits
better.  This enables some tidying which is the subject of a later patch.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The previous DEBUG_SHIRQ patch missed one case.  The console doesn't
set its host descriptors non-blocking.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the host side of a console can't be opened, this will now produce visible
error messages.

enable_chan now returns a status and this is passed up to con_open and
ssl_open, which will complain if anything went wrong.

The default host device for the serial line driver is now a pts device rather
than a pty device since lots of hosts have LEGACY_PTYS disabled.  This had
always been failing on such hosts, but silently.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Rename os_{read_write}_file_k back to os_{read_write}_file, delete
the originals and their bogus infrastructure, and fix all the callers.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert all remaining os_{read_write}_file users to use the simple
{read,write} wrappers, os_{read_write}_file_k.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

user_util.h isn't needed any more, so delete it and remove all includes of it.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As the comment immediately preceding this points out, this list is changed in
irq context, so it needs to be protected with spin_lock_irqsave in process
context when it is processed.

Sometimes, gcc should just compile the comments and forget the code.

The IRQ side of this was better, in the sense that it blocked and unblocked
interrupts, but it still should have saved and restored them.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The chan_opts structure is mostly const, and needs no locking.  Comment the
lack of locking on the one field that can change.

Make all the other fields const.  It turned out that console_open_chan didn't
use its chan_opts argument, so that is deleted from the function and its
callers.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix (i.e. add some) the locking around the irqs_to_free list.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I noticed that errors happening while hotplugging devices from the host were
never returned back to the mconsole client.  In some cases, success was
returned instead of even an information-free error.

This patch cleans that up by having the low-level configuration code pass back
an error string along with an error code.  At the top level, which knows
whether it is early boot time or responding to an mconsole request, the string
is printk'd or returned to the mconsole client.

There are also whitespace and trivial code cleanups in the surrounding code.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix up arch-specific work items where possible to use the new work_struct and
delayed_work structs.

Three places that enqueue bits of their stack and then return have been marked
with #error as this is not permitted.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>

Make lots of structures const in order to make it obvious that they need no
locking.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There were a bunch of missed ARRAY_SIZE opportunities.

Also, some formatting fixes in the affected areas of code.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix some simple sparse warnings - a lot more staticness and a misplaced
__user.
Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
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>

This patch adds support for throttling and unthrottling input when the tty
driver can't handle it.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When the tty flip_buf is full, it's a good idea to delay the input processing
for a jiffy, rather than just scheduling the tasklet immediately.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch simplifies the opening and closing of host console devices and the
registration and deregistration of IRQs.  The intent is to make it obvious
that an IRQ can't exist without an open file descriptor.

chan_enable will now open the channel, and when both opening and IRQ
registration are desired, this should be used.  Opening only is done for the
initial console, so that interface still needs to exist.

The free_irqs_later interface is now gone.  It was intended to avoid freeing
an IRQ while it was being processed.  It did this, but it didn't eliminate the
possiblity of free_irq being called from an interrupt, which is bad.  In its
place is a list of irqs to be freed, which is processed by the signal handler
just before exiting.  close_one_chan now disables irqs.

When a host device disappears, it is just closed, and that disables IRQs.

The device id registered with the IRQ is now the chan structure, not the tty.
This is because the interrupt arrives on a descriptor associated with the
channel.  This caused equivalent changes in the arguments to line_timer_cb.
line_disable is gone since it is not used any more.

The count field in the line structure is gone.  tty->count is used instead.

The complicated logic in sigio_handler with freeing IRQs when necessary and
making sure its idea of the next irq is correct is now much simpler.  The irq
list can't be rearranged underneath it, so it is now a simple list walk.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch changes when console devices are configured in order to prepare the
ground for the next patch.

parse_chan_pair is now done earlier, when initcalls are run, rather than when
the device is opened.

When a host device disappears, the channel list is closed, but not freed.
This is required by the previous change.  line_config now takes the options
structure as an argument, and line_open doesn't.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This removes a structure field which turned out to be pointless, and
references to it.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch makes a bunch of non-functional changes -
    return(foo); becomes return foo;
    some statements are broken across lines for readability
    some trailing whitespace is cleaned up
    open_one_chan took four arguments, three of which could be
       deduced from the first.  Accordingly, they were eliminated.
    some examples of "} else {" had a newline added
    some whitespace cleanup in the indentation
    lines_init got some control flow cleanup
    some long lines were broken
    removed another emacs-specific C formatting comment
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Since the 4th param is unused, remove it altogether.
Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

User get *a lot* confused when consoles don't work but we don't report
anything.  And, as reported in the comment, using printk to report "your
console doesn't work" isn't likely to go that far.

Fix the problem on the base of this: stack consumption by host printf().  Use
kernel sprintf() and os_write_file, using a wild guess that one page will be
enough for the message, to preallocate the buffer with kmalloc().
Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

setup_initial_poll is only called with sigio_lock() held, so use appropriate
allocation.

Also, parse_chan() can also be called when holding a spinlock (see line_open()
 -> parse_chan_pair()).

I have sporadic problems (spinlock taken twice, with spinlock debugging on UP)
which could be caused by a sequence like "take spinlock, alloc and go to
sleep, take again the spinlock in the other thread".
Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

From: Al Viro - we have error messages with KERN_ERR in them, so they
should be printk-ed rather than printf-ed.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix some console locking problems (including scheduling in atomic) and various
reorderings and cleanup in that code.  Not yet ready for 2.6.12 probably.
Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>