The tty count sanity check may need the BKL, that isn't clear. However it
is clear that the count use of the lock is internal and independant of the
bigger use of the lock.

Furthermore the file list locking is also separately locked already
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

There are two call points, both want to check that tty->signal->leader is
set. Move the test into disassociate_ctty() as that will make locking
changes easier in a bit
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

We know that the redirect field is handled via its own locking in all
places
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Start trying to untangle the remaining BKL mess

Updated to fix missing unlock_kernel noted by Dan Carpenter
Signed-off-by: NAlan "I must be out of my tree" Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

moxa_openlock is used for several situations where we want to handle the
case of an ioctl that crosses many ports (not just the open tty), and also
cases where an open races a deinit (eg a pci unplug) and we hangup a port
before we can cope with that.

The non open race cases can use the moxa_lock spinlock. This simplifies sorting
out the remaining mess.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

It isn't needed here any more
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This is overkill and mostly not needed
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The tty flag can be tested so the shadow flag isn't needed
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

- The open lock is needed to fix up the case of a board reset occuring during
  tty open but too early for a sane hangup response.
- The lock can however got for other cases
- Use the port mutex for get/setserial
- Fix up the confused lack of locking on the THROTTLE and other bits in the
  private flags. Just use set/test/clear bit and it covers the cases we need
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Introduce a lock for moxafunc() to protect the cases where were get collisions
between two function requests at the same time.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Rework a few bits of this into tty_port format
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Alexander Strakh <strakh@ispras.ru> reported

	KERNEL_VERSION: 2.6.31
	DESCRIBE:
Driver drivers/char/isicom.c might sleep in atomic  context, because it
calls 
tty_port_xmit_buf under spin_lock.

./drivers/char/isicom.c:
1307 static void isicom_hangup(struct tty_struct *tty)
1308 {
...
1315         spin_lock_irqsave(&port->card->card_lock, flags);
1316         isicom_shutdown_port(port);
...

Path to might_sleep macro from isicom_hangup:
1. isicom_hangup calls spin_lock_irqsave (drivers/char/isicom.c:1315) and
then 
calls isicom_shutdown_port.
2. isiscom_shutdown_port calls tty_port_free_xmit_buf at 
drivers/char/isicom.c:906
3. tty_port_free_xmit_buf calls mutex_lock at drivers/char/tty_port:48

Found by Linux Driver Verification Project.
Reported-by: NAlexander Strakh <strakh@ispras.ru>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Propogate the init/shutdown mutex through the setserial logic. Use the proper
locks for the various bits still using the BKL. Kill the BKL in this driver.

Updated to fix the bug noted by Dan Carpenter
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

At first this looks a fairly trivial conversion but we can't quite push
everything into the right format yet. The open side is easy but care is needed
over the setserial methods. Fix up the locking now that we've adopted the
port->mutex locking rule for the initialization.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Split this into two flags - INIT meaning the board is set up and ACTIVE
meaning the board has ports open. Remove the broken HUPCL casing and push
the counts somewhere sensible.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Trivial conversion in this case so might as well do it while testing the
port_open design is right
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Users of tty port need a way to refcount ports when hotplugging is
involved.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Slice/dice/repeat as with the stallion driver this is just code shuffling
and removal
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The driver is already structured this way so just slice and dice
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Some devices want to set IO_ERROR in their activate methods so that you can
be handed a 'dead' port for operations like setserial. Thus we need to
clear the flag before activate so that activate can choose to set the flag
and still return 0.

This is fine as the file handle/tty are not accessible to the user yet.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

To propogate tty_port_open/close to a few other devices we need to start
handling the IO_ERROR flag on the tty. We can do this pretty trivially.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

We want to be able to do this without regard for the activate/own open
method being used which causes a problem using port->mutex. Add another
mutex for now. Once everything uses port_open to do buffer allocs we can
kill it back off
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The new dtr_rts function didn't take the port->func lock as it should
so add use of the lock there.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add the POSIX block for carrier

Linux TIOCMIWAIT functionality is still lacking from the driver.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Running the current code through checkpatch shows a few bits of noise
mostly but not entirely from before the changes.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Switching between two non standard baud rates fails because of the cflag
test. Do as we did elsewhere and just kill the "optimisation".
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Gets us proper tty semantics, removes some code and fixes up a few corner
case races (hangup during open etc)
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

When we move to the tty_port logic the port mutex will protect open v close
v hangup. Move to this first in the existing open code so we have a bisection
point.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The tty can go away underneath us, so we must refcount it. Do the naïve
implementation initially. We will worry about startup shortly.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Now... testing reveals that the very first patch "sdio_uart: use
tty_port" causes a segmentation fault in sdio_uart_open():

Unable to handle kernel NULL pointer dereference at virtual address 00000084
pgd = dfb44000 [00000084] *pgd=1fb99031, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT
last sysfs file:
/sys/devices/platform/mvsdio/mmc_host/mmc0/mmc0:f111/uevent
Modules linked in:
CPU: 0    Not tainted  (2.6.32-rc5-next-20091102-00001-gb36eae9 #10)
PC is at sdio_uart_open+0x204/0x2cc
[...]
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add a tty_port object to the sdio uart. For the moment just begin using the
tty field of the port, as this is the critical one to clean up.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Move the HUCPL handling from the end of close_port_start to the beginning
of close_port_end. What this actually does is change the ordering from

	port shutdown
	port->dtr_rts

to

	port->dtr_rts
	port shutdown

Some hardware drops the physical connection on shutdown so we must perform
the port operations before the shutdown.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

devpts_get_tty() assumes that the inode passed in is associated with a valid
pty.  But if the only reference to the pty is via a bind-mount, the inode
passed to devpts_get_tty() while valid, would refer to a pty that no longer
exists.

With a lot of debug effort, Grzegorz Nosek developed a small program (see
below) to reproduce a crash on recent kernels. This crash is a regression
introduced by the commit:

	commit 527b3e47
	Author: Sukadev Bhattiprolu <sukadev@us.ibm.com>
	Date:   Mon Oct 13 10:43:08 2008 +0100

To fix, ensure that the dentry associated with the inode has not yet been
deleted/unhashed by devpts_pty_kill().

See also:
https://lists.linux-foundation.org/pipermail/containers/2009-July/019273.html 

tty-bug.c:

#define _GNU_SOURCE
#include <fcntl.h>
#include <sched.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/signal.h>
#include <unistd.h>
#include <stdio.h>

#include <linux/fs.h>

void dummy(int sig)
{
}

static int child(void *unused)
{
	int fd;

	signal(SIGINT, dummy); signal(SIGHUP, dummy);
	pause(); /* cheesy synchronisation to wait for /dev/pts/0 to appear */

	mount("/dev/pts/0", "/dev/console", NULL, MS_BIND, NULL);
	sleep(2);

	fd = open("/dev/console", O_RDWR);
	dup(0); dup(0);
	write(1, "Hello world!\n", sizeof("Hello world!\n")-1);
	return 0;
}

int main(void)
{
	pid_t pid;
	char *stack;

	stack = malloc(16384);
	pid = clone(child, stack+16384, CLONE_NEWNS|SIGCHLD, NULL);

	open("/dev/ptmx", O_RDWR|O_NOCTTY|O_NONBLOCK);

	unlockpt(fd); grantpt(fd);

	sleep(2);
	kill(pid, SIGHUP);
	sleep(1);
	return 0; /* exit before child opens /dev/console */
}
Reported-by: NGrzegorz Nosek <root@localdomain.pl>
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: NSerge Hallyn <serue@us.ibm.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Do not read IIR in serial8250_start_tx when UART_BUG_TXEN

Reading the IIR clears some oustanding interrupts so it is not safe.
Instead, simply transmit immediately if the buffer is empty without
regard to IIR.
Signed-off-by: NIan Jackson <ian.jackson@eu.citrix.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NJiri Kosina <jkosina@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

A small addition to the ldisc method descriptions.
Signed-off-by: NTilman Schmidt <tilman@imap.cc>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Intel(R) PXA27x Processor Family Specification Update (Nov 2005)
says:

  E75. UART: Baud rate may not be programmed correctly on
       back-to-back writes.

  Problem:
  When programming the Divisor Latch registers, Low and High (DLL and
  DLH), with back-to-back writes, the second register write may not
  take effect. The result is an incorrect baud rate.

  Workaround:
  After programming the first Divisor Latch register, read and verify
  it before programming the second Divisor Latch register.

This was hit when changing the baud rate from 115200 to 9600 while
receiving characters at 9600 Bd.

And fixed indention of some comments nearby.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: NWolfram Sang <w.sang@pengutronix.de>
Acked-by: NMarc Kleine-Budde <mkl@pengutronix.de>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NAndré Goddard Rosa <andre.goddard@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NAndré Goddard Rosa <andre.goddard@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>