commit 8bfbe2de769afda051c56aba5450391670e769fc upstream.

Commit 19e2ad6a09f0c06dbca19c98e5f4584269d913dd ("n_tty: Remove overflow
tests from receive_buf() path") moved the increment of read_head into
the arguments list of read_buf_addr(). Function calls represent a
sequence point in C. Therefore read_head is incremented before the
character c is placed in the buffer. Since the circular read buffer is
a lock-less design since commit 6d76bd2618535c581f1673047b8341fd291abc67
("n_tty: Make N_TTY ldisc receive path lockless"), this creates a race
condition that leads to communication errors.

This patch modifies the code to increment read_head _after_ the data
is placed in the buffer and thus fixes the race for non-SMP machines.
To fix the problem for SMP machines, memory barriers must be added in
a separate patch.

Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 1ff383a4c3eda8893ec61b02831826e1b1f46b41 upstream.

This patch adds waiting until transmit buffer and shifter will be empty
before clock disabling.

Without this fix it's possible to have clock disabled while data was
not transmited yet, which causes unproper state of TX line and problems
in following data transfers.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 6b1f40cf4840820051d69646af0b6503878cb1bc upstream.

The mcb_device_id table is supposed to be zero-terminated.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 2dea53bf57783f243c892e99c10c6921e956aa7e.

Turns out to be broken :(

Cc: Jingchang Lu <jingchang.lu@freescale.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit f95499c3030f ("n_tty: Don't wait for buffer work in read() loop")
introduces a race window where a pty master can be signalled that the pty
slave was closed before all the data that the slave wrote is delivered.
Commit f8747d4a466a ("tty: Fix pty master read() after slave closes") fixed the
problem in case of n_tty_read, but the problem still exists for n_tty_poll.
This can be seen by running 'for ((i=0; i<100;i++));do ./test.py ;done'
where test.py is:

import os, select, pty

(pid, pty_fd) = pty.fork()

if pid == 0:
   os.write(1, 'This string should be received by parent')
else:
   poller = select.epoll()
   poller.register( pty_fd, select.EPOLLIN )
   ready = poller.poll( 1 * 1000 )
   for fd, events in ready:
      if not events & select.EPOLLIN:
         print 'missed POLLIN event'
      else:
         print os.read(fd, 100)
   poller.close()

The string from the slave is missed several times.
This patch takes the same approach as the fix for read and special cases
this condition for poll.
Tested on 3.16.

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The info pointer points to an uninitialized kmalloced space.
If a device doesn't have clk property, then info->clk may
have unpredicated value and cause call trace. So use kzalloc
to make sure it is NULL initialized.

Signed-off-by: Jingchang Lu <jingchang.lu@freescale.com>
Acked-by: Arnd Bergmann <arnd@arndb.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We can call this function for a dummy console that doesn't support
setting the font mapping, which will result in a null ptr BUG. So check
for this case and return error for consoles w/o font mapping support.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=59321
Signed-off-by: Imre Deak <imre.deak@intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The calculation of value quot for highspeed register set to three
was wrong. This patch fixes the calculation so that the serial port
for baudrates bigger then 576000 baud is working correctly.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Only print one warning when a task is on the read_wait or write_wait
wait queue at final tty release.

Cc: <stable@vger.kernel.org> # 3.4.x+
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Kernel oops can cause the tty to be unreleaseable (for example, if
n_tty_read() crashes while on the read_wait queue). This will cause
tty_release() to endlessly loop without sleeping.

Use a killable sleep timeout which grows by 2n+1 jiffies over the interval
[0, 120 secs.) and then jumps to forever (but still killable).

NB: killable just allows for the task to be rewoken manually, not
to be terminated.

Cc: <stable@vger.kernel.org> # since before 2.6.32
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>