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  1. 19 3月, 2013 1 次提交
    • P
      tty: Add safe tty throttle/unthrottle functions · 70bc1264
      由 Peter Hurley 提交于 
      The tty driver can become stuck throttled due to race conditions
between throttle and unthrottle, when the decision to throttle
or unthrottle is conditional. The following example helps to
illustrate the race:

  CPU 0                        |  CPU 1
                               |
if (condition A)               |
                               | <processing such that A not true>
                               | if (!condition A)
                               |     unthrottle()
    throttle()                 |
                               |

Note the converse is also possible; ie.,

  CPU 0                        |  CPU 1
                               |
                               | if (!condition A)
<processing such that A true>  |
if (condition A)               |
    throttle()                 |
                               |     unthrottle()
                               |

Add new throttle/unthrottle functions based on the familiar model
of task state and schedule/wake. For example,

    while (1) {
        tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
        if (!condition)
            break;
        if (!tty_throttle_safe(tty))
            break;
    }
    __tty_set_flow_change(tty, 0);

In this example, if an unthrottle occurs after the condition is
evaluated but before tty_throttle_safe(), then tty_throttle_safe()
will return non-zero, looping and forcing the re-evaluation of
condition.
Reported-by: NVincent Pillet <vincentx.pillet@intel.com>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      70bc1264
  3. 05 2月, 2013 1 次提交
  5. 19 1月, 2013 1 次提交
    • I
      tty: Add driver unthrottle in ioctl(...,TCFLSH,..). · a1bf9584
      由 Ilya Zykov 提交于 
      Regression 'tty: fix "IRQ45: nobody cared"'
Regression commit 7b292b4b

  Function reset_buffer_flags() also invoked during the ioctl(...,TCFLSH,..).
At the time of request we can have full buffers and throttled driver too.
If we don't unthrottle driver, we can get forever throttled driver, because,
after request, we will have empty buffers and throttled driver and
there is no place to unthrottle driver.
It simple reproduce with "pty" pair then one side sleep on tty->write_wait,
and other side do ioctl(...,TCFLSH,..). Then there is no place to do writers wake up.
Signed-off-by: NIlya Zykov <ilya@ilyx.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a1bf9584
  7. 26 10月, 2012 1 次提交
  9. 18 7月, 2012 1 次提交
  11. 17 7月, 2012 1 次提交
  13. 29 3月, 2012 1 次提交
  15. 19 10月, 2011 1 次提交
    • T
      tty: Support compat_ioctl get/set termios_locked · 8193c429
      由 Thomas Meyer 提交于 
      When running a Fedora 15 (x86) on an x86_64 kernel, in the boot process
plymouthd complains about those two missing ioctls:
[    2.581783] ioctl32(plymouthd:186): Unknown cmd fd(10) cmd(00005457){t:'T';sz:0} arg(ffb6a5d0) on /dev/tty1
[    2.581803] ioctl32(plymouthd:186): Unknown cmd fd(10) cmd(00005456){t:'T';sz:0} arg(ffb6a680) on /dev/tty1

both ioctl functions work on the 'struct termios' resp. 'struct termios2',
which has the same size (36 bytes resp. 44 bytes) on x86 and x86_64,
so it's just a matter of converting the pointer from userland.
Signed-off-by: NThomas Meyer <thomas@m3y3r.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAndrew Morton <akpm@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
      8193c429
  17. 20 4月, 2011 1 次提交
  19. 12 4月, 2011 1 次提交
  21. 31 3月, 2011 1 次提交
  23. 18 2月, 2011 1 次提交
  25. 05 11月, 2010 1 次提交
  27. 11 8月, 2010 1 次提交
    • H
      tty: Add EXTPROC support for LINEMODE · 26df6d13
      由 hyc@symas.com 提交于 
      This patch is against the 2.6.34 source.

Paraphrased from the 1989 BSD patch by David Borman @ cray.com:

     These are the changes needed for the kernel to support
     LINEMODE in the server.

     There is a new bit in the termios local flag word, EXTPROC.
     When this bit is set, several aspects of the terminal driver
     are disabled.  Input line editing, character echo, and mapping
     of signals are all disabled.  This allows the telnetd to turn
     off these functions when in linemode, but still keep track of
     what state the user wants the terminal to be in.

     New ioctl:
         TIOCSIG         Generate a signal to processes in the
                         current process group of the pty.

     There is a new mode for packet driver, the TIOCPKT_IOCTL bit.
     When packet mode is turned on in the pty, and the EXTPROC bit
     is set, then whenever the state of the pty is changed, the
     next read on the master side of the pty will have the TIOCPKT_IOCTL
     bit set.  This allows the process on the server side of the pty
     to know when the state of the terminal has changed; it can then
     issue the appropriate ioctl to retrieve the new state.

Since the original BSD patches accompanied the source code for telnet
I've left that reference here, but obviously the feature is useful for
any remote terminal protocol, including ssh.

The corresponding feature has existed in the BSD tty driver since 1989.
For historical reference, a good copy of the relevant files can be found
here:

http://anonsvn.mit.edu/viewvc/krb5/trunk/src/appl/telnet/?pathrev=17741Signed-off-by: NHoward Chu <hyc@symas.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
      26df6d13
  29. 09 11月, 2009 1 次提交
  31. 20 9月, 2009 1 次提交
  33. 13 7月, 2009 1 次提交
  35. 17 6月, 2009 1 次提交
  37. 11 6月, 2009 2 次提交
    • A
      tty: Untangle termios and mm mutex dependencies · 26a2e20f
      由 Alan Cox 提交于 
      Although this doesn't cause any problems it could potentially do so for
future mmap using devices. No real work is needed to sort it out so untangle
it before it causes problems
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      26a2e20f
    • A
      tty: throttling race fix · 38db8979
      由 Alan Cox 提交于 
      The tty throttling code can race due to the lock drops. It takes very high
loads but this has been observed and verified by Rob Duncan.

The basic problem is that on an SMP box we can go

	CPU #1				CPU #2
	need to throttle ?
	suppose we should		buffer space cleared
					are we throttled
					yes ? - unthrottle
	call throttle method

This changeet take the termios lock to protect against this. The termios
lock isn't the initial obvious candidate but many implementations of throttle
methods already need to poke around their own termios structures (and nobody
really locks them against a racing change of flow control).

This does mean that anyone who is setting tty->low_latency = 1 and then
calling tty_flip_buffer_push from their unthrottle method is going to end up
collapsing in a pile of locks. However we've removed all the known bogus
users of low_latency = 1 and such use isn't safe anyway for other reasons so
catching it would be an improvement.
Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      38db8979
  39. 16 1月, 2009 1 次提交
  41. 14 10月, 2008 4 次提交
  43. 28 8月, 2008 1 次提交
  45. 21 7月, 2008 1 次提交
    • A
      tty: Ldisc revamp · a352def2
      由 Alan Cox 提交于 
      Move the line disciplines towards a conventional ->ops arrangement.  For
the moment the actual 'tty_ldisc' struct in the tty is kept as part of
the tty struct but this can then be changed if it turns out that when it
all settles down we want to refcount ldiscs separately to the tty.

Pull the ldisc code out of /proc and put it with our ldisc code.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a352def2
  47. 24 6月, 2008 1 次提交
  49. 30 4月, 2008 6 次提交
  51. 09 2月, 2008 1 次提交
  53. 09 1月, 2008 1 次提交
  55. 24 12月, 2007 1 次提交
    • C
      tty: fix logic change introduced by wait_event_interruptible_timeout() · db99247a
      由 Cory T. Tusar 提交于 
      Commit 5a52bd4a introduced a subtle logic
change in tty_wait_until_sent().  The original version would only error out
of the 'do { ...  } while (timeout)' loop if signal_pending() evaluated to
true; a timeout or break due to an empty buffer would fall out of the loop
and into the tty->driver->wait_until_sent handling.  The current
implementation will error out on either a pending signal or an empty
buffer, falling through to the tty->driver->wait_until_sent handling only
on a timeout.

The ->wait_until_sent() will not be reached if the buffer empties before
timeout jiffies have elapsed.  This behavior differs from that prior to commit
5a52bd4a.

I turned this up while using a little serial download utility to bootstrap an
ARM-based eval board.  The util worked fine on 2.6.22.x, but consistently
failed on 2.6.23.x.  Once I'd determined that, I narrowed things down with git
bisect, and found the above difference in logic in tty_wait_until_sent() by
inspection.

This change reverts the logic flow in tty_wait_until_sent() to match that
prior to the aforementioned commit.
Signed-off-by: NCory T. Tusar <ctusar@videon-central.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NJiri Slaby <jirislaby@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      db99247a
  57. 07 11月, 2007 1 次提交
    • A
      [TTY]: Fix network driver interactions with TCGET/SET calls. · 0fc00e24
      由 Alan Cox 提交于 
      Dave Miller noted various cases where line disciplines for things like
ppp go poking around in termios themselves in ways that broke with the
new termios code. Rather than have them all learning about termios
internals provide proper methods for this

- tty_mode_ioctl()

	This handles all the terminal mode handling for speed/carrier
etc and none of the methods are ldisc dependant so they can be called
by any user

- tty_perform_flush()

	This extracts the flush functionality and enables pppd the ppp
layer to share it cleanly.

The existing n_tty_ioctl code is refactored in this patch to provide
the new functions and to call them itself appropriately. This patch
has no (intended) behaviour changes and simply prepares for the other
fixes.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0fc00e24
  59. 20 10月, 2007 1 次提交
  61. 19 10月, 2007 1 次提交