Commit graph

240 commits

Author SHA1 Message Date
Peter Hurley
e2dfa3d387 tty: core: Add tty_debug() for printk(KERN_DEBUG) messages
Introduce tty_debug() macro to output uniform debug information for
tty core debug messages (function name and tty name).

Note: printk(KERN_DEBUG) is retained here over pr_debug() since
messages can be enabled in non-DEBUG builds.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-23 18:37:31 -07:00
Greg Kroah-Hartman
02730d3c05 Merge 4.1-rc4 into tty-next
This resolves some tty driver merge issues.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-18 14:08:58 -07:00
Peter Hurley
1a48632ffe pty: Fix input race when closing
A read() from a pty master may mistakenly indicate EOF (errno == -EIO)
after the pty slave has closed, even though input data remains to be read.
For example,

       pty slave       |        input worker        |    pty master
                       |                            |
                       |                            |   n_tty_read()
pty_write()            |                            |     input avail? no
  add data             |                            |     sleep
  schedule worker  --->|                            |     .
                       |---> flush_to_ldisc()       |     .
pty_close()            |       fill read buffer     |     .
  wait for worker      |       wakeup reader    --->|     .
                       |       read buffer full?    |---> input avail ? yes
                       |<---   yes - exit worker    |     copy 4096 bytes to user
  TTY_OTHER_CLOSED <---|                            |<--- kick worker
                       |                            |

		                **** New read() before worker starts ****

                       |                            |   n_tty_read()
                       |                            |     input avail? no
                       |                            |     TTY_OTHER_CLOSED? yes
                       |                            |     return -EIO

Several conditions are required to trigger this race:
1. the ldisc read buffer must become full so the input worker exits
2. the read() count parameter must be >= 4096 so the ldisc read buffer
   is empty
3. the subsequent read() occurs before the kicked worker has processed
   more input

However, the underlying cause of the race is that data is pipelined, while
tty state is not; ie., data already written by the pty slave end is not
yet visible to the pty master end, but state changes by the pty slave end
are visible to the pty master end immediately.

Pipeline the TTY_OTHER_CLOSED state through input worker to the reader.
1. Introduce TTY_OTHER_DONE which is set by the input worker when
   TTY_OTHER_CLOSED is set and either the input buffers are flushed or
   input processing has completed. Readers/polls are woken when
   TTY_OTHER_DONE is set.
2. Reader/poll checks TTY_OTHER_DONE instead of TTY_OTHER_CLOSED.
3. A new input worker is started from pty_close() after setting
   TTY_OTHER_CLOSED, which ensures the TTY_OTHER_DONE state will be
   set if the last input worker is already finished (or just about to
   exit).

Remove tty_flush_to_ldisc(); no in-tree callers.

Fixes: 52bce7f8d4 ("pty, n_tty: Simplify input processing on final close")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96311
BugLink: http://bugs.launchpad.net/bugs/1429756
Cc: <stable@vger.kernel.org> # 3.19+
Reported-by: Andy Whitcroft <apw@canonical.com>
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-10 19:26:37 +02:00
Rasmus Villemoes
429b474990 tty: remove buf parameter from tty_name()
tty_name no longer uses the buf parameter, so remove it along with all
the 64 byte stack buffers that used to be passed in.

Mostly generated by the coccinelle script

@depends on patch@
identifier buf;
constant C;
expression tty;
@@
- char buf[C];
  <+...
- tty_name(tty, buf)
+ tty_name(tty)
  ...+>

allmodconfig compiles, so I'm fairly confident the stack buffers
weren't used for other purposes as well.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-06 22:26:57 +02:00
Rasmus Villemoes
1d6b98774c tty: constify return type of tty_name
All users of tty_name pass the result directly to a printf-like
function. This means we can actually let tty_name return the literal
"NULL tty" or tty->name directly, avoiding the strcpy and a lot of
medium-sized stack buffers. In preparation for that, make the return
type const char*.

While at it, we can also constify the tty parameter.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-06 22:26:57 +02:00
Frederic Danis
b00f5c2dc0 tty: Re-add external interface for tty_set_termios()
This is needed by Bluetooth hci_uart module to be able to change speed
of Bluetooth controller and local UART.

Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-04-28 14:26:20 +02:00
Peter Hurley
632f32e210 tty: Remove external interface for tty_set_termios()
tty_set_termios() is an internal helper intended for file scope use.

UART drivers which are capable of driving the RTS pin must
properly handle the tiocmset() method, regardless of termios settings.
A failure to do so is a UART driver bug and should be fixed there.
Do not use this interface to workaround UART driver bugs.

Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: <linux-bluetooth@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02 10:11:28 -08:00
Peter Hurley
d2b6f44779 n_tty: Fix signal handling flushes
BRKINT and ISIG requires input and output flush when a signal char
is received. However, the order of operations is significant since
parallel i/o may be ongoing.

Merge the signal handling for BRKINT with ISIG handling.

Process the signal first. This ensures any ongoing i/o is aborted;
without this, a waiting writer may continue writing after the flush
occurs and after the signal char has been echoed.

Write lock the termios_rwsem, which excludes parallel writers from
pushing new i/o until after the output buffers are flushed; claiming
the write lock is necessary anyway to exclude parallel readers while
the read buffer is flushed.

Subclass the termios_rwsem for ptys since the slave pty performing
the flush may appear to reorder the termios_rwsem->tty buffer lock
lock order; adding annotation clarifies that
  slave tty_buffer lock-> slave termios_rwsem -> master tty_buffer lock
is a valid lock order.

Flush the echo buffer. In this context, the echo buffer is 'output'.
Otherwise, the output will appear discontinuous because the output buffer
was cleared which contains older output than the echo buffer.

Open-code the read buffer flush since the input worker does not need
kicking (this is the input worker).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02 10:11:27 -08:00
Peter Hurley
1d1d14da12 pty: Fix buffer flush deadlock
The pty driver does not clear its write buffer when commanded.
This is to avoid an apparent deadlock between parallel flushes from
both pty ends; specifically when handling either BRK or INTR input.
However, parallel flushes from this source is not possible since
the pty master can never be set to BRKINT or ISIG. Parallel flushes
from other sources are possible but these do not threaten deadlocks.

Annotate the tty buffer mutex for lockdep to represent the nested
tty_buffer locking which occurs when the pty slave is processing input
(its buffer mutex held) and receives INTR or BRK and acquires the
linked tty buffer mutex via tty_buffer_flush().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02 10:11:27 -08:00
Peter Hurley
3abf87cd3e tty: Make lock subclasses available for other tty locks
Besides nested legacy_mutex locking which is required on pty pair
teardown, other nested pty operations require lock subclassing.

Move lock subclass definition to tty interface header, include/linux/tty.h,
and document its use.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02 10:11:27 -08:00
Peter Hurley
413ba63853 tty: Convert tty->closing to int
tty->closing is a bitfield member; prevent corruption from non-atomic
update by assigning a unique memory location.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 14:57:27 -08:00
Peter Hurley
b9104f5cec tty: Remove defunct serial_console_init() declaration
serial_console_init() is not defined by the tty core; remove
declaration.

Note that the powerpc arch boot code contains a serial_console_init()
declaration in arch/powerpc/boot/ops.h which is restricted to
the powerpc arch boot.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 20:18:30 -08:00
Peter Hurley
1d597e7c26 tty: Remove defunct pcxe_open() declaration
pcxe_open() has no definition in mainline; remove declaration.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 20:18:30 -08:00
Peter Hurley
86c80a8e2a tty: Flush ldisc buffer atomically with tty flip buffers
tty_ldisc_flush() first clears the line discipline input buffer,
then clears the tty flip buffers. However, this allows for existing
data in the tty flip buffers to be added after the ldisc input
buffer has been cleared, but before the flip buffers have been cleared.

Add an optional ldisc parameter to tty_buffer_flush() to allow
tty_ldisc_flush() to pass the ldisc to clear.

NB: Initially, the plan was to do this automatically in
tty_buffer_flush(). However, an audit of the behavior of existing
line disciplines showed that performing a ldisc buffer flush on
ioctl(TCFLSH) was not always the outcome. For example, some line
disciplines have flush_buffer() methods but not ioctl() methods,
so a ->flush_buffer() command would be unexpected.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:43 -08:00
Peter Hurley
35af935ee4 tty: Remove tty_unhangup() declaration
The tty_unhangup() function is not defined.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:42 -08:00
Peter Hurley
2febdb632b tty: Preset lock subclass for nested tty locks
Eliminate the requirement of specifying the tty lock nesting at
lock time; instead, set the lock subclass for slave ptys at pty
install (normal ttys and master ptys use subclass 0).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:42 -08:00
Peter Hurley
2aff5e2bc6 tty: Change tty lock order to master->slave
When releasing the master pty, the slave pty also needs to be locked
to prevent concurrent tty count changes for the slave pty and to
ensure that only one parallel master and slave release observe the
final close, and proceed to destruct the pty pair. Conversely, when
releasing the slave pty, locking the master pty is not necessary
(since the master's state can be inferred by the slave tty count).

Introduce tty_lock_slave()/tty_unlock_slave() which acquires/releases
the tty lock of the slave pty. Remove tty_lock_pair()/tty_unlock_pair().

Dropping the tty_lock is no longer required to re-establish a stable
lock order.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:50:42 -08:00
Peter Hurley
62462aefeb tty: Simplify tty_ldisc_release() interface
Passing the 'other' tty to tty_ldisc_release() only makes sense
for a pty pair; make o_tty function local instead.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:42:46 -08:00
Peter Hurley
04980706c8 tty: Remove TTY_CLOSING
Now that re-open is not permitted for a legacy BSD pty master,
using TTY_CLOSING to indicate when a tty can be torn-down is
no longer necessary.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:24:10 -08:00
Peter Hurley
3ff51a199f tty: Remove TTY_HUPPING
Now that tty_ldisc_hangup() does not drop the tty lock, it is no
longer possible to observe TTY_HUPPING while holding the tty lock
on another cpu.

Remove TTY_HUPPING bit definition.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 18:24:10 -08:00
Peter Hurley
8f166e0019 tty: Remove tty_pair_get_tty()/tty_pair_get_pty() api
tty_pair_get_pty() has no in-tree users and tty_pair_get_tty()
has only one file-local user. Remove the external declarations,
the export declarations, and declare tty_pair_get_tty() static.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-05 16:26:13 -08:00
Peter Hurley
cc952e7017 tty: Fix width of unsigned long bitfield padding
Commit c545b66c69,
'tty: Serialize tcflow() with other tty flow control changes' and
commit 99416322dd,
'tty: Workaround Alpha non-atomic byte storage in tty_struct' work around
compiler bugs and non-atomic storage on multiple arches by padding
bitfields out to the declared type which is unsigned long. However, the
width varies by arch.

Pad bitfields to actual width of unsigned long (which is BITS_PER_LONG).

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-25 12:17:25 +02:00
Peter Hurley
99416322dd tty: Workaround Alpha non-atomic byte storage in tty_struct
The Alpha EV4/EV5 cpus can corrupt adjacent byte and short data because
those cpus use RMW to store byte and short data. Thus, concurrent adjacent
byte stores could become corrupted, if serialized by a different lock.
tty_struct uses different locks to protect certain fields within the
structure, and thus is vulnerable to byte stores which are not atomic.

Merge the ->ctrl_status byte and packet mode bit, both protected by the
->ctrl_lock, into an unsigned long.

The padding bits are necessary to force the compiler to allocate the
type specified; otherwise, gcc will ignore the type specifier and
allocate the minimum number of bytes required to store the bitfield.
In turn, this would allow Alpha EV4/EV5 cpus to corrupt adjacent byte
or short storage (because those cpus use RMW to store byte and short data).

gcc versions < 4.7.2 will also corrupt storage adjacent to bitfields
smaller than unsigned long on ia64, ppc64, hppa64, and sparc64, thus
requiring more than unsigned int storage (which would otherwise be
sufficient to fix the Alpha non-atomic storage problem).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:36 -07:00
Peter Hurley
136d5258b2 tty: Move and rename send_prio_char() as tty_send_xchar()
Relocate the file-scope function, send_prio_char(), as a global
helper tty_send_xchar(). Remove the global declarations for
tty_write_lock()/tty_write_unlock(), as these are file-scope only now.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Peter Hurley
c545b66c69 tty: Serialize tcflow() with other tty flow control changes
Use newly-introduced tty->flow_lock to serialize updates to
tty->flow_stopped (via tcflow()) and with concurrent tty flow
control changes from other sources.

Merge the storage for ->stopped and ->flow_stopped, now that both
flags are serialized by ->flow_lock.

The padding bits are necessary to force the compiler to allocate the
type specified; otherwise, gcc will ignore the type specifier and
allocate the minimum number of bytes necessary to store the bitfield.
In turn, this would allow Alpha EV4 and EV5 cpus to corrupt adjacent
byte storage because those cpus use RMW to store byte and short data.

gcc versions < 4.7.2 will also corrupt storage adjacent to bitfields
smaller than unsigned long on ia64, ppc64, hppa64 and sparc64, thus
requiring more than unsigned int storage (which would otherwise be
sufficient to workaround the Alpha non-atomic byte/short storage problem).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Peter Hurley
f9e053dcfc tty: Serialize tty flow control changes with flow_lock
Without serialization, the flow control state can become inverted
wrt. the actual hardware state. For example,

CPU 0                          | CPU 1
stop_tty()                     |
  lock ctrl_lock               |
  tty->stopped = 1             |
  unlock ctrl_lock             |
                               | start_tty()
                               |   lock ctrl_lock
                               |   tty->stopped = 0
                               |   unlock ctrl_lock
                               |   driver->start()
  driver->stop()               |

In this case, the flow control state now indicates the tty has
been started, but the actual hardware state has actually been stopped.

Introduce tty->flow_lock spinlock to serialize tty flow control changes.
Split out unlocked __start_tty()/__stop_tty() flavors for use by
ioctl(TCXONC) in follow-on patch.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Peter Hurley
d7a855bd6a tty: Convert tty_struct bitfield to ints
The stopped, hw_stopped, flow_stopped and packet bits are smp-unsafe
and interrupt-unsafe. For example,

CPU 0                         | CPU 1
                              |
tty->flow_stopped = 1         | tty->hw_stopped = 0

One of these updates will be corrupted, as the bitwise operation
on the bitfield is non-atomic.

Ensure each flag has a separate memory location, so concurrent
updates do not corrupt orthogonal states. Because DEC Alpha EV4 and EV5
cpus (from 1995) perform RMW on smaller-than-machine-word storage,
"separate memory location" must be int instead of byte.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-09-23 21:19:35 -07:00
Rasmus Villemoes
2c964a2f41 drivers: tty: Merge alloc_tty_struct and initialize_tty_struct
The two functions alloc_tty_struct and initialize_tty_struct are
always called together. Merge them into alloc_tty_struct, updating its
prototype and the only two callers of these functions.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-11 17:54:28 -07:00
Peter Hurley
5fbf1a65dd Revert "tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc"
This reverts commit 6a20dbd6ca.

Although the commit correctly identifies an unsafe race condition
between __tty_buffer_request_room() and flush_to_ldisc(), the commit
fixes the race with an unnecessary spinlock in a lockless algorithm.

The follow-on commit, "tty: Fix lockless tty buffer race" fixes
the race locklessly.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-03 18:14:28 -04:00
Manfred Schlaegl
6a20dbd6ca tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc
The race was introduced while development of linux-3.11 by
e8437d7ecb and
e9975fdec0.
Originally it was found and reproduced on linux-3.12.15 and
linux-3.12.15-rt25, by sending 500 byte blocks with 115kbaud to the
target uart in a loop with 100 milliseconds delay.

In short:
 1. The consumer flush_to_ldisc is on to remove the head tty_buffer.
 2. The producer adds a number of bytes, so that a new tty_buffer must
	be allocated and added by __tty_buffer_request_room.
 3. The consumer removes the head tty_buffer element, without handling
	newly committed data.

Detailed example:
 * Initial buffer:
   * Head, Tail -> 0: used=250; commit=250; read=240; next=NULL
 * Consumer: ''flush_to_ldisc''
   * consumed 10 Byte
   * buffer:
     * Head, Tail -> 0: used=250; commit=250; read=250; next=NULL
{{{
		count = head->commit - head->read;	// count = 0
		if (!count) {				// enter
			// INTERRUPTED BY PRODUCER ->
			if (head->next == NULL)
				break;
			buf->head = head->next;
			tty_buffer_free(port, head);
			continue;
		}
}}}
 * Producer: tty_insert_flip_... 10 bytes + tty_flip_buffer_push
   * buffer:
     * Head, Tail -> 0: used=250; commit=250; read=250; next=NULL
   * added 6 bytes: head-element filled to maximum.
     * buffer:
       * Head, Tail -> 0: used=256; commit=250; read=250; next=NULL
   * added 4 bytes: __tty_buffer_request_room is called
     * buffer:
       * Head -> 0: used=256; commit=256; read=250; next=1
       * Tail -> 1: used=4; commit=0; read=250 next=NULL
   * push (tty_flip_buffer_push)
     * buffer:
       * Head -> 0: used=256; commit=256; read=250; next=1
       * Tail -> 1: used=4; commit=4; read=250 next=NULL
 * Consumer
{{{
		count = head->commit - head->read;
		if (!count) {
			// INTERRUPTED BY PRODUCER <-
			if (head->next == NULL)		// -> no break
				break;
			buf->head = head->next;
			tty_buffer_free(port, head);
			// ERROR: tty_buffer head freed -> 6 bytes lost
			continue;
		}
}}}

This patch reintroduces a spin_lock to protect this case. Perhaps later
a lock-less solution could be found.

Signed-off-by: Manfred Schlaegl <manfred.schlaegl@gmx.at>
Cc: stable <stable@vger.kernel.org> # 3.11
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-24 15:18:02 -07:00
Linus Torvalds
cd6362befe Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:
 "Here is my initial pull request for the networking subsystem during
  this merge window:

   1) Support for ESN in AH (RFC 4302) from Fan Du.

   2) Add full kernel doc for ethtool command structures, from Ben
      Hutchings.

   3) Add BCM7xxx PHY driver, from Florian Fainelli.

   4) Export computed TCP rate information in netlink socket dumps, from
      Eric Dumazet.

   5) Allow IPSEC SA to be dumped partially using a filter, from Nicolas
      Dichtel.

   6) Convert many drivers to pci_enable_msix_range(), from Alexander
      Gordeev.

   7) Record SKB timestamps more efficiently, from Eric Dumazet.

   8) Switch to microsecond resolution for TCP round trip times, also
      from Eric Dumazet.

   9) Clean up and fix 6lowpan fragmentation handling by making use of
      the existing inet_frag api for it's implementation.

  10) Add TX grant mapping to xen-netback driver, from Zoltan Kiss.

  11) Auto size SKB lengths when composing netlink messages based upon
      past message sizes used, from Eric Dumazet.

  12) qdisc dumps can take a long time, add a cond_resched(), From Eric
      Dumazet.

  13) Sanitize netpoll core and drivers wrt.  SKB handling semantics.
      Get rid of never-used-in-tree netpoll RX handling.  From Eric W
      Biederman.

  14) Support inter-address-family and namespace changing in VTI tunnel
      driver(s).  From Steffen Klassert.

  15) Add Altera TSE driver, from Vince Bridgers.

  16) Optimizing csum_replace2() so that it doesn't adjust the checksum
      by checksumming the entire header, from Eric Dumazet.

  17) Expand BPF internal implementation for faster interpreting, more
      direct translations into JIT'd code, and much cleaner uses of BPF
      filtering in non-socket ocntexts.  From Daniel Borkmann and Alexei
      Starovoitov"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1976 commits)
  netpoll: Use skb_irq_freeable to make zap_completion_queue safe.
  net: Add a test to see if a skb is freeable in irq context
  qlcnic: Fix build failure due to undefined reference to `vxlan_get_rx_port'
  net: ptp: move PTP classifier in its own file
  net: sxgbe: make "core_ops" static
  net: sxgbe: fix logical vs bitwise operation
  net: sxgbe: sxgbe_mdio_register() frees the bus
  Call efx_set_channels() before efx->type->dimension_resources()
  xen-netback: disable rogue vif in kthread context
  net/mlx4: Set proper build dependancy with vxlan
  be2net: fix build dependency on VxLAN
  mac802154: make csma/cca parameters per-wpan
  mac802154: allow only one WPAN to be up at any given time
  net: filter: minor: fix kdoc in __sk_run_filter
  netlink: don't compare the nul-termination in nla_strcmp
  can: c_can: Avoid led toggling for every packet.
  can: c_can: Simplify TX interrupt cleanup
  can: c_can: Store dlc private
  can: c_can: Reduce register access
  can: c_can: Make the code readable
  ...
2014-04-02 20:53:45 -07:00
Peter Hurley
a9c3f68f3c tty: Fix low_latency BUG
The user-settable knob, low_latency, has been the source of
several BUG reports which stem from flush_to_ldisc() running
in interrupt context. Since 3.12, which added several sleeping
locks (termios_rwsem and buf->lock) to the input processing path,
the frequency of these BUG reports has increased.

Note that changes in 3.12 did not introduce this regression;
sleeping locks were first added to the input processing path
with the removal of the BKL from N_TTY in commit
a88a69c912,
'n_tty: Fix loss of echoed characters and remove bkl from n_tty'
and later in commit 38db89799b,
'tty: throttling race fix'. Since those changes, executing
flush_to_ldisc() in interrupt_context (ie, low_latency set), is unsafe.

However, since most devices do not validate if the low_latency
setting is appropriate for the context (process or interrupt) in
which they receive data, some reports are due to misconfiguration.
Further, serial dma devices for which dma fails, resort to
interrupt receiving as a backup without resetting low_latency.

Historically, low_latency was used to force wake-up the reading
process rather than wait for the next scheduler tick. The
effect was to trim multiple milliseconds of latency from
when the process would receive new data.

Recent tests [1] have shown that the reading process now receives
data with only 10's of microseconds latency without low_latency set.

Remove the low_latency rx steering from tty_flip_buffer_push();
however, leave the knob as an optional hint to drivers that can
tune their rx fifos and such like. Cleanup stale code comments
regarding low_latency.

[1] https://lkml.org/lkml/2014/2/20/434

"Yay.. thats an annoying historical pain in the butt gone."
	-- Alan Cox

Reported-by: Beat Bolli <bbolli@ewanet.ch>
Reported-by: Pavel Roskin <proski@gnu.org>
Acked-by: David Sterba <dsterba@suse.cz>
Cc: Grant Edwards <grant.b.edwards@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Hal Murray <murray+fedora@ip-64-139-1-69.sjc.megapath.net>
Cc: <stable@vger.kernel.org> # 3.12.x+
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-28 16:31:00 -08:00
Peter Hurley
c0fdfb8038 tty: Fix ref counting for port krefs
The tty core supports two models for handling tty_port lifetimes;
the tty_port can use the kref supplied by tty_port (which will
automatically destruct the tty_port when the ref count drops to
zero) or it can destruct the tty_port manually.

For tty drivers that choose to use the port kref to manage the
tty_port lifetime, it is not possible to safely acquire a port
reference conditionally. If the last reference is released after
evaluating the condition but before acquiring the reference, a
bogus reference will be held while the tty_port destruction
commences.

Rather, only acquire a port reference if the ref count is non-zero
and allow the caller to distinguish if a reference has successfully
been acquired.

Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-02-14 13:39:29 -08:00
Linus Torvalds
ec513b16c4 USB patches for 3.14-rc1
Here's the big USB pull request for 3.14-rc1
 
 Lots of little things all over the place, and the usual USB gadget
 updates, and XHCI fixes (some for an issue reported by a lot of people.)
 USB PHY updates as well as chipidea updates and fixes.
 
 All of these have been in the linux-next tree with no reported issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.22 (GNU/Linux)
 
 iEYEABECAAYFAlLdjwIACgkQMUfUDdst+ylBIQCgkRoR8lJc0L5lZ3fugIJL4IzZ
 j6AAn0nBLP6VI0cvUEi3TcrPTzv4MEuL
 =Yb+I
 -----END PGP SIGNATURE-----

Merge tag 'usb-3.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB updates from Greg KH:
 "Here's the big USB pull request for 3.14-rc1

  Lots of little things all over the place, and the usual USB gadget
  updates, and XHCI fixes (some for an issue reported by a lot of
  people).  USB PHY updates as well as chipidea updates and fixes.

  All of these have been in the linux-next tree with no reported issues"

* tag 'usb-3.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (318 commits)
  usb: chipidea: udc: using MultO at TD as real mult value for ISO-TX
  usb: chipidea: need to mask INT_STATUS when write otgsc
  usb: chipidea: put hw_phymode_configure before ci_usb_phy_init
  usb: chipidea: Fix Internal error: : 808 [#1] ARM related to STS flag
  usb: chipidea: imx: set CI_HDRC_IMX28_WRITE_FIX for imx28
  usb: chipidea: add freescale imx28 special write register method
  usb: ehci: add freescale imx28 special write register method
  usb: core: check for valid id_table when using the RefId feature
  usb: cdc-wdm: resp_count can be 0 even if WDM_READ is set
  usb: core: bail out if user gives an unknown RefId when using new_id
  usb: core: allow a reference device for new_id
  usb: core: add sanity checks when using bInterfaceClass with new_id
  USB: image: correct spelling mistake in comment
  USB: c67x00: correct spelling mistakes in comments
  usb: delete non-required instances of include <linux/init.h>
  usb:hub set hub->change_bits when over-current happens
  Revert "usb: chipidea: imx: set CI_HDRC_IMX28_WRITE_FIX for imx28"
  xhci: Set scatter-gather limit to avoid failed block writes.
  xhci: Avoid infinite loop when sg urb requires too many trbs
  usb: gadget: remove unused variable in gr_queue_int()
  ...
2014-01-20 16:13:02 -08:00
Andrew Lunn
e58b57a354 tty: Add C_CMSPAR(tty)
Add the missing C_CMSPAR(tty) macro.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-03 12:32:32 -08:00
Chuansheng Liu
e12348c6d0 tty: Removing the deprecated function tty_vhangup_locked()
The function tty_vhangup_locked() was deprecated, removed it
from the tty.h also.

Signed-off-by: Liu, Chuansheng <chuansheng.liu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-18 16:59:11 -08:00
Peter Hurley
acc0f67f30 tty: Halve flip buffer GFP_ATOMIC memory consumption
tty flip buffers use GFP_ATOMIC allocations for received data
which is to be processed by the line discipline. For each byte
received, an extra byte is used to indicate the error status of
that byte.

Instead, if the received data is error-free, encode the entire
buffer without status bytes.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-09 11:09:24 -08:00
Peter Hurley
5dda4ca558 tty: Rename tty buffer memory_used field
Trim up the memory_used field name to mem_used.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-08 16:57:38 -08:00
Peter Hurley
4d18e6eff8 tty: Enable configurable tty flip buffer limit
Allow driver to configure its maximum flip buffer memory
consumption/limit. This is necessary for very-high speed line
rates (in excess of 10MB/sec) because the flip buffers can
be saturated before the line discipline has a chance to
throttle the input.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-08 16:57:38 -08:00
Linus Torvalds
39cf275a1a Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes from Ingo Molnar:
 "The main changes in this cycle are:

   - (much) improved CONFIG_NUMA_BALANCING support from Mel Gorman, Rik
     van Riel, Peter Zijlstra et al.  Yay!

   - optimize preemption counter handling: merge the NEED_RESCHED flag
     into the preempt_count variable, by Peter Zijlstra.

   - wait.h fixes and code reorganization from Peter Zijlstra

   - cfs_bandwidth fixes from Ben Segall

   - SMP load-balancer cleanups from Peter Zijstra

   - idle balancer improvements from Jason Low

   - other fixes and cleanups"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
  ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
  stop_machine: Fix race between stop_two_cpus() and stop_cpus()
  sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus
  sched: Fix asymmetric scheduling for POWER7
  sched: Move completion code from core.c to completion.c
  sched: Move wait code from core.c to wait.c
  sched: Move wait.c into kernel/sched/
  sched/wait: Fix __wait_event_interruptible_lock_irq_timeout()
  sched: Avoid throttle_cfs_rq() racing with period_timer stopping
  sched: Guarantee new group-entities always have weight
  sched: Fix hrtimer_cancel()/rq->lock deadlock
  sched: Fix cfs_bandwidth misuse of hrtimer_expires_remaining
  sched: Fix race on toggling cfs_bandwidth_used
  sched: Remove extra put_online_cpus() inside sched_setaffinity()
  sched/rt: Fix task_tick_rt() comment
  sched/wait: Fix build breakage
  sched/wait: Introduce prepare_to_wait_event()
  sched/wait: Add ___wait_cond_timeout() to wait_event*_timeout() too
  sched: Remove get_online_cpus() usage
  sched: Fix race in migrate_swap_stop()
  ...
2013-11-12 10:20:12 +09:00
Peter Zijlstra
35a2af94c7 sched/wait: Make the __wait_event*() interface more friendly
Change all __wait_event*() implementations to match the corresponding
wait_event*() signature for convenience.

In particular this does away with the weird 'ret' logic. Since there
are __wait_event*() users this requires we update them too.

Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131002092529.042563462@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-04 10:16:25 +02:00
Peter Zijlstra
0d1e1c8a43 sched/wait: Collapse __wait_event_interruptible_tty()
Reduce macro complexity by using the new ___wait_event() helper.
No change in behaviour, identical generated code.

Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131002092528.831085521@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-04 10:16:20 +02:00
Peter Zijlstra
2f2a2b60ad sched/wait: Make the signal_pending() checks consistent
There's two patterns to check signals in the __wait_event*() macros:

  if (!signal_pending(current)) {
	schedule();
	continue;
  }
  ret = -ERESTARTSYS;
  break;

And the more natural:

  if (signal_pending(current)) {
	ret = -ERESTARTSYS;
	break;
  }
  schedule();

Change them all into the latter form.

Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131002092527.956416254@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-04 10:14:44 +02:00
Peter Hurley
469d6d0631 tty: Remove unused drop() method from tty_port interface
Although originally conceived as a hook for port drivers to know
when a port reference is dropped, no driver uses this method.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-25 18:08:34 -07:00
Peter Hurley
dee4a0be69 tty: Fix lock order in tty_do_resize()
Commits 6a1c0680cf and
9356b535fc, respectively
  'tty: Convert termios_mutex to termios_rwsem' and
  'n_tty: Access termios values safely'
introduced a circular lock dependency with console_lock and
termios_rwsem.

The lockdep report [1] shows that n_tty_write() will attempt
to claim console_lock while holding the termios_rwsem, whereas
tty_do_resize() may already hold the console_lock while
claiming the termios_rwsem.

Since n_tty_write() and tty_do_resize() do not contend
over the same data -- the tty->winsize structure -- correct
the lock dependency by introducing a new lock which
specifically serializes access to tty->winsize only.

[1] Lockdep report

======================================================
[ INFO: possible circular locking dependency detected ]
3.10.0-0+tip-xeon+lockdep #0+tip Not tainted
-------------------------------------------------------
modprobe/277 is trying to acquire lock:
 (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0

but task is already holding lock:
 ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 ((fb_notifier_list).rwsem){.+.+.+}:
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff8175b797>] down_read+0x47/0x5c
       [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0
       [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
       [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
       [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
       [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
       [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
       [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
       [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
       [<ffffffff813b1701>] pci_device_probe+0x111/0x120
       [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
       [<ffffffff81497bab>] __driver_attach+0xab/0xb0
       [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
       [<ffffffff814971fe>] driver_attach+0x1e/0x20
       [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
       [<ffffffff814982b7>] driver_register+0x77/0x170
       [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
       [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
       [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
       [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
       [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
       [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

-> #1 (console_lock){+.+.+.}:
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff810430a7>] console_lock+0x77/0x80
       [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50
       [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0
       [<ffffffff814541b9>] tty_write+0x159/0x2e0
       [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0
       [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0
       [<ffffffff811abec5>] SyS_write+0x55/0xa0
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

-> #0 (&tty->termios_rwsem){++++..}:
       [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff8175b724>] down_write+0x44/0x70
       [<ffffffff81452656>] tty_do_resize+0x36/0xe0
       [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0
       [<ffffffff8146c99f>] vc_resize+0x1f/0x30
       [<ffffffff813e4535>] fbcon_init+0x385/0x5a0
       [<ffffffff8146a4bc>] visual_init+0xbc/0x120
       [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320
       [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70
       [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0
       [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820
       [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110
       [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0
       [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
       [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
       [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
       [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
       [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
       [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
       [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
       [<ffffffff813b1701>] pci_device_probe+0x111/0x120
       [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
       [<ffffffff81497bab>] __driver_attach+0xab/0xb0
       [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
       [<ffffffff814971fe>] driver_attach+0x1e/0x20
       [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
       [<ffffffff814982b7>] driver_register+0x77/0x170
       [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
       [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
       [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
       [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
       [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
       [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

other info that might help us debug this:

Chain exists of:
  &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((fb_notifier_list).rwsem);
                               lock(console_lock);
                               lock((fb_notifier_list).rwsem);
  lock(&tty->termios_rwsem);

 *** DEADLOCK ***

7 locks held by modprobe/277:
 #0:  (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0
 #1:  (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0
 #2:  (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm]
 #3:  (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320
 #4:  (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60
 #5:  (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320
 #6:  ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0

stack backtrace:
CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip
Hardware name: Dell Inc. Precision WorkStation T5400  /0RW203, BIOS A11 04/30/2012
 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8
 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8
 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007
Call Trace:
 [<ffffffff81755f19>] dump_stack+0x19/0x1b
 [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c
 [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30
 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120
 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0
 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0
 [<ffffffff8175b724>] down_write+0x44/0x70
 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0
 [<ffffffff81452656>] tty_do_resize+0x36/0xe0
 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0
 [<ffffffff8146c99f>] vc_resize+0x1f/0x30
 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0
 [<ffffffff8146a4bc>] visual_init+0xbc/0x120
 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320
 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70
 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0
 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820
 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110
 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0
 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
 [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0
 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290
 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper]
 [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
 [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
 [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
 [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
 [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80
 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
 [<ffffffff813b1701>] pci_device_probe+0x111/0x120
 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
 [<ffffffff81497bab>] __driver_attach+0xab/0xb0
 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0
 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
 [<ffffffff814971fe>] driver_attach+0x1e/0x20
 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffff814982b7>] driver_register+0x77/0x170
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
 [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0
 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-24 15:12:53 -07:00
Peter Hurley
40d5e0905a n_tty: Fix EOF push handling
In canonical mode, an EOF which is not the first character of the line
causes read() to complete and return the number of characters read so
far (commonly referred to as EOF push). However, if the previous read()
returned because the user buffer was full _and_ the next character
is an EOF not at the beginning of the line, read() must not return 0,
thus mistakenly indicating the end-of-file condition.

The TTY_PUSH flag is used to indicate an EOF was received which is not
at the beginning of the line. Because the EOF push condition is
evaluated by a thread other than the read(), multiple EOF pushes can
cause a premature end-of-file to be indicated.

Instead, discover the 'EOF push as first read character' condition
from the read() thread itself, and restart the i/o loop if detected.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-23 17:08:40 -07:00
Peter Hurley
9114fe8ccf tty: Remove private constant from global namespace
TTY_BUFFER_PAGE is only used within drivers/tty/tty_buffer.c;
relocate to that file scope.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-23 16:47:10 -07:00
Peter Hurley
a7c8d58c79 tty: Fix unsafe vt paste_selection()
Convert the tty_buffer_flush() exclusion mechanism to a
public interface - tty_buffer_lock/unlock_exclusive() - and use
the interface to safely write the paste selection to the line
discipline.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-23 16:47:10 -07:00
Peter Hurley
0f56bd2f6a tty: Use non-atomic state to signal flip buffer flush pending
Atomic bit ops are no longer required to indicate a flip buffer
flush is pending, as the flush_mutex is sufficient barrier.

Remove the unnecessary port .iflags field and localize flip buffer
state to struct tty_bufhead.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-23 16:47:09 -07:00
Peter Hurley
8c1fb49ba1 tty: Avoid false-sharing flip buffer ptrs
Separate the head and tail ptrs to avoid cache-line contention
(so called 'false-sharing') between concurrent threads.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-23 16:47:09 -07:00