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Al Viro 2f46a2c1d4 tty_ioctl(): start taking TIOC[SG]SERIAL into separate methods
->set_serial() and ->get_serial() resp., both taking tty and
a kernel pointer to serial_struct.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-09-14 11:19:30 -04:00
Christoph Hellwig 8a8dcabffb tty: replace ->proc_fops with ->proc_show
Just set up the show callback in the tty_operations, and use
proc_create_single_data to create the file without additional
boilerplace code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
2018-05-16 07:24:30 +02:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Masatake YAMATO d01c3289e7 pty: show associative slave of ptmx in fdinfo
This patch adds "tty-index" field to /proc/PID/fdinfo/N if N
specifies /dev/ptmx. The field shows the index of associative
slave pts.

Though a minor number is given for each pts instance, ptmx is not.
It means there is no way in user-space to know the association between
file descriptors for pts/n and ptmx. (n = 0, 1, ...)

This is different from pipe. About pipe such association can be solved
by inode of pipefs.

Providing the way to know the association between pts/n and ptmx helps
users understand the status of running system. lsof can utilize this field.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-08-28 20:51:23 +02:00
Kees Cook 3859a271a0 randstruct: Mark various structs for randomization
This marks many critical kernel structures for randomization. These are
structures that have been targeted in the past in security exploits, or
contain functions pointers, pointers to function pointer tables, lists,
workqueues, ref-counters, credentials, permissions, or are otherwise
sensitive. This initial list was extracted from Brad Spengler/PaX Team's
code in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.

Left out of this list is task_struct, which requires special handling
and will be covered in a subsequent patch.

Signed-off-by: Kees Cook <keescook@chromium.org>
2017-06-30 12:00:51 -07:00
Linus Torvalds 8ead9dd547 devpts: more pty driver interface cleanups
This is more prep-work for the upcoming pty changes.  Still just code
cleanup with no actual semantic changes.

This removes a bunch pointless complexity by just having the slave pty
side remember the dentry associated with the devpts slave rather than
the inode.  That allows us to remove all the "look up the dentry" code
for when we want to remove it again.

Together with moving the tty pointer from "inode->i_private" to
"dentry->d_fsdata" and getting rid of pointless inode locking, this
removes about 30 lines of code.  Not only is the end result smaller,
it's simpler and easier to understand.

The old code, for example, depended on the d_find_alias() to not just
find the dentry, but also to check that it is still hashed, which in
turn validated the tty pointer in the inode.

That is a _very_ roundabout way to say "invalidate the cached tty
pointer when the dentry is removed".

The new code just does

	dentry->d_fsdata = NULL;

in devpts_pty_kill() instead, invalidating the tty pointer rather more
directly and obviously.  Don't do something complex and subtle when the
obvious straightforward approach will do.

The rest of the patch (ie apart from code deletion and the above tty
pointer clearing) is just switching the calling convention to pass the
dentry or file pointer around instead of the inode.

Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Jann Horn <jann@thejh.net>
Cc: Greg KH <greg@kroah.com>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Florian Weimer <fw@deneb.enyo.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-26 15:47:32 -07:00
Richard Watts a3a10ce342 Avoid usb reset crashes by making tty_io cdevs truly dynamic
Avoid usb reset crashes by making tty_io cdevs truly dynamic

Signed-off-by: Richard Watts <rrw@kynesim.co.uk>
Reported-by: Duncan Mackintosh <DMackintosh@cbnl.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-08-03 15:24:43 -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 ed617e4423 tty: Document locking for tty driver methods
The tty core calls the tty driver's open, close and hangup
methods holding the tty lock.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-10 16:05:19 -07:00
Peter Hurley 7be88b4ccb tty: Document required behavior of tty driver close()
If the tty driver open() fails, the tty driver close() is still
called during the resultant tty release.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-02-04 15:40:28 -08:00
Jiri Slaby 7e73eca6a7 TTY: move cdev_add to tty_register_device
We need the /dev/ node not to be available before we call
tty_register_device. Otherwise we might race with open and
tty_struct->port might not be available at that time.

This is not an issue now, but would be a problem after "TTY: use
tty_port_register_device" is applied.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-13 16:45:39 -07:00
Jiri Slaby 0019b4089c TTY: add support for unnumbered device nodes
This allows drivers like ttyprintk to avoid hacks to create an
unnumbered node in /dev. It used to set TTY_DRIVER_DYNAMIC_DEV in
flags and call device_create on its own. That is incorrect, because
TTY_DRIVER_DYNAMIC_DEV may be set only if tty_register_device is
called explicitly.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-13 16:45:38 -07:00
Jiri Slaby 21aca2fa00 TTY: pty, switch to tty_alloc_driver
Switch to the new driver allocation interface, as this is one of the
special call-sites. Here, we need TTY_DRIVER_DYNAMIC_ALLOC to not
allocate tty_driver->ports, cdevs and potentially other structures
because we reserve too many lines in pty. Instead, it provides the
tty_port<->tty_struct link in tty->ops->install already.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-13 16:45:38 -07:00
Jiri Slaby 7f0bc6a68e TTY: pass flags to alloc_tty_driver
We need to allow drivers that use neither tty_port_install nor
tty_port_register_device to link a tty_port to a tty somehow.  To
avoid a race with open, this has to be performed before
tty_register_device. But currently tty_driver->ports is allocated even
in tty_register_device because we do not know whether this is the PTY
driver. The PTY driver is special here due to an excessive count of
lines it declares to handle. We cannot handle tty_ports there this
way.

To circumvent this, we start passing tty_driver flags to
alloc_tty_driver already and we create tty_alloc_driver for this
purpose. There we can allocate tty_driver->ports and do all the magic
between tty_alloc_driver and tty_register_device. Later we will
introduce tty_port_link_device function for that purpose.

All drivers should eventually switch to this new tty driver allocation
interface.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-08-10 13:29:58 -07:00
Alan Cox 36b3c070d2 tty: Move the handling of the tty release logic
Now that we don't have tty->termios tied to drivers->tty we can untangle
the logic here. In addition we can push the removal logic out of the
destructor path.

At that point we can think about sorting out tty_port and console and all
the other ugly hangovers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-17 09:13:38 -07:00
Jiri Slaby 04831dc154 TTY: add ports array to tty_driver
It will hold tty_port structures for all drivers which do not want to
define tty->ops->install hook.

We ignore PTY here because it wants 1 million lines and it installs
tty_port in ->install anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-06-13 17:30:54 -07:00
Jiri Slaby 26b23209c0 TTY: tty_driver, document tty->ops->shutdown limitation
Note that tty->ops->shutdown is called from whatever context the user
drops the last tty reference from. E.g. if one takes a reference in
an ISR, tty close happens on other CPU and the final tty put is from
the ISR, tty->ops->shutdown will be called from that hard irq context.

We would have a problem in vt if we start using tty refcounting from
other contexts than user there. It is because vt's shutdown uses
mutexes. This is yet to be fixed.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-03-08 11:38:51 -08:00
Jiri Slaby 87cab16beb TTY: remove minor_num from tty_driver
It was added back in 2004 and never used for anything real. Remove the
only assignment in the tree as well.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-03-08 11:30:21 -08:00
Jiri Slaby 1a54a76d51 TTY: let alloc_tty_driver deduce the owner automatically
Like the rest of the kernel, make a stub from alloc_tty_driver which
calls __alloc_tty_driver with proper owner. This will save us one more
assignment on the driver side.

Also this fixes some drivers which didn't set the owner. This allowed
user to remove the module from the system even though a tty from the
driver is still open.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-03-08 11:30:21 -08:00
Konstantin Khlebnikov 20c300b10c tty: remove unused tty_driver->termios_locked
This field is unused since 2.6.28 (commit fe6e29fdb1a7: "tty: simplify
ktermios allocation", to be exact)

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-17 10:30:38 -08:00
Jiri Slaby 24d406a6bf TTY: pty, fix pty counting
tty_operations->remove is normally called like:
queue_release_one_tty
 ->tty_shutdown
   ->tty_driver_remove_tty
     ->tty_operations->remove

However tty_shutdown() is called from queue_release_one_tty() only if
tty_operations->shutdown is NULL. But for pty, it is not.
pty_unix98_shutdown() is used there as ->shutdown.

So tty_operations->remove of pty (i.e. pty_unix98_remove()) is never
called. This results in invalid pty_count. I.e. what can be seen in
/proc/sys/kernel/pty/nr.

I see this was already reported at:
  https://lkml.org/lkml/2009/11/5/370
But it was not fixed since then.

This patch is kind of a hackish way. The problem lies in ->install. We
allocate there another tty (so-called tty->link). So ->install is
called once, but ->remove twice, for both tty and tty->link. The fix
here is to count both tty and tty->link and divide the count by 2 for
user.

And to have ->remove called, let's make tty_driver_remove_tty() global
and call that from pty_unix98_shutdown() (tty_operations->shutdown).

While at it, let's document that when ->shutdown is defined,
tty_shutdown() is not called.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-08-23 10:10:38 -07:00
Alan Cox 6caa76b778 tty: now phase out the ioctl file pointer for good
Only oddities here are a couple of drivers that bogusly called the ldisc
helpers instead of returning -ENOIOCTLCMD. Fix the bug and the rest goes
away.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-02-17 11:59:56 -08:00
Alan Cox 20b9d17715 tiocmset: kill the file pointer argument
Doing tiocmget was such fun we should do tiocmset as well for the same
reasons

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-02-17 11:52:43 -08:00
Alan Cox 60b33c133c tiocmget: kill off the passing of the struct file
We don't actually need this and it causes problems for internal use of
this functionality. Currently there is a single use of the FILE * pointer.
That is the serial core which uses it to check tty_hung_up_p. However if
that is true then IO_ERROR is also already set so the check may be removed.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-02-17 11:47:33 -08:00
Timur Tabi 6ce5b1ce5f tty: fix typos/errors in tty_driver.h comments
Fix various typos and other errors in comments of tty_driver.h.  The most
significant is the wrong name of a function for the description of
TTY_DRIVER_DYNAMIC_DEV.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-12-16 13:14:32 -08:00
Jiri Slaby 3dfbd044d0 TTY: include termios.h in tty_driver.h
We reference termios and termiox in tty_driver.h, but we do not include
linux/termios.h where these are defined. Add the #include properly.

Otherwise when we include tty_driver.h, we get compile errors.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-11-16 12:50:17 -08:00
Alan Cox d281da7ff6 tty: Make tiocgicount a handler
Dan Rosenberg noted that various drivers return the struct with uncleared
fields. Instead of spending forever trying to stomp all the drivers that
get it wrong (and every new driver) do the job in one place.

This first patch adds the needed operations and hooks them up, including
the needed USB midlayer and serial core plumbing.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-10-22 10:20:04 -07:00
Dave Young f278a2f7bb tty: Fix regressions caused by commit b50989dc
The following commit made console open fails while booting:

	commit b50989dc44
	Author: Alan Cox <alan@linux.intel.com>
	Date:   Sat Sep 19 13:13:22 2009 -0700

	tty: make the kref destructor occur asynchronously

Due to tty release routines run in a workqueue now, error like the
following will be reported while booting:

INIT open /dev/console Input/output error

It also causes hibernation regression to appear as reported at
http://bugzilla.kernel.org/show_bug.cgi?id=14229

The reason is that now there's latency issue with closing, but when
we open a "closing not finished" tty, -EIO will be returned.

Fix it as per the following Alan's suggestion:

  Fun but it's actually not a bug and the fix is wrong in itself as
  the port may be closing but not yet being destructed, in which case
  it seems to do the wrong thing.  Opening a tty that is closing (and
  could be closing for long periods) is supposed to return -EIO.

  I suspect a better way to deal with this and keep the old console
  timing is to split tty->shutdown into two functions.

  tty->shutdown() - called synchronously just before we dump the tty
  onto the waitqueue for destruction

  tty->cleanup() - called when the destructor runs.

  We would then do the shutdown part which can occur in IRQ context
  fine, before queueing the rest of the release (from tty->magic = 0
  ...  the end) to occur asynchronously

  The USB update in -next would then need a call like

       if (tty->cleanup)
               tty->cleanup(tty);

  at the top of the async function and the USB shutdown to be split
  between shutdown and cleanup as the USB resource cleanup and final
  tidy cannot occur synchronously as it needs to sleep.

  In other words the logic becomes

       final kref put
               make object unfindable

       async
               clean it up

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
[ rjw: Rebased on top of 2.6.31-git, reworked the changelog. ]
Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl>
[ Changed serial naming to match new rules, dropped tty_shutdown as per
  comments from Alan Stern  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-27 13:35:16 -07:00
Alan Cox 38db89799b tty: throttling race fix
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: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-11 08:50:59 -07:00
Adrian Bunk f786ddd285 tty: Correct inline types for tty_driver_kref_get()
tty_driver_kref_get() should be static inline and not extern inline
(the latter even changed it's semantics in gcc >= 4.3).

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-07 08:44:04 -07:00
Alexey Dobriyan 0f043a81eb proc tty: remove struct tty_operations::read_proc
struct tty_operations::proc_fops took it's place and there is one less
create_proc_read_entry() user now!

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-01 08:59:10 -07:00
Alexey Dobriyan ae149b6bec proc tty: add struct tty_operations::proc_fops
Used for gradual switch of TTY drivers from using ->read_proc which helps
with gradual switch from ->read_proc for the whole tree.

As side effect, fix possible race condition when ->data initialized after
PDE is hooked into proc tree.

->proc_fops takes precedence over ->read_proc.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-01 08:59:08 -07:00
Alan Cox fc6f623822 pty: simplify resize
We have special case logic for resizing pty/tty pairs. We also have a per
driver resize method so for the pty case we should use it.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02 10:19:36 -08:00
Sukadev Bhattiprolu 15f1a6338d Add an instance parameter devpts interfaces
Pass-in 'inode' or 'tty' parameter to devpts interfaces.  With multiple
devpts instances, these parameters will be used in subsequent patches
to identify the instance of devpts mounted. The parameters also help
simplify devpts implementation.

Changelog[v3]:
	- minor changes due to merge with ttydev updates
	- rename parameters to emphasize they are ptmx or pts inodes
	- pass-in tty_struct * to devpts_pty_kill() (this will help
	  cleanup the get_node() call in a subsequent patch)

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:43 -07:00
Alan Cox 8b0a88d591 tty: More driver operations
We have the lookup operation abstracted which is nice for pty cleanup but
we really want to abstract the add/remove entries as well so that we can
pull the pty code out of the tty core and create a clear defined interface
for the tty driver table.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:42 -07:00
Alan Cox 7d7b93c145 tty: kref the tty driver object
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:42 -07:00
Alan Cox 99f1fe189d tty: Clean up the tty_init_dev changes further
Fix up the naming, style and extract some bits of code into the driver
specific code

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:42 -07:00
Alan Cox feebed6515 tty: shutdown method
Right now there are various drivers that try to use tty->count to know when
they get the final close. Aristeau Rozanski showed while debugging the vt
sysfs race that this isn't entirely safe.

Instead of driver side tricks to work around this introduce a shutdown which
is called when the tty is being destructed. This also means that the shutdown
method is tied into the refcounting.

Use this to rework the console close/sysfs logic.

Remove lots of special case code from the tty core code. The pty code can now
have a shutdown() method that replaces the special case hackery in the tree
free up paths.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:42 -07:00
Alan Cox 1d65b4a088 tty: Add termiox
We need a way to describe the various additional modes and flow control
features that random weird hardware shows up and software such as wine
wants to emulate as Windows supports them.

TCGETX/TCSETX and the termiox ioctl are a SYS5 extension that we might as
well adopt. This patches adds the structures and the basic ioctl interfaces
when the TCGETX etc defines are added for an architecture. Drivers wishing
to use this stuff need to add new methods.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:40 -07:00
Alan Cox 8c9a9dd0fa tty: remove resize window special case
This moves it to being a tty operation. That removes special cases and now
also means that resize can be picked up by um and other non vt consoles
which may have a resize operation.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-15 10:34:07 -07:00
Alan Cox 9e98966c7b tty: rework break handling
Some hardware needs to do break handling itself and may have partial
support only. Make break_ctl return an error code. Add a tty driver flag
so you can indicate driver hardware side break support.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-22 13:03:28 -07:00
Alan Cox 36c7343b4e tty_driver: Update required method documentation
Some of the requirement rules are now more relaxed. Also correct a
contradiction in the previous update

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-23 10:36:47 -07:00
Alan Cox 39c2e60f8c tty: add throttle/unthrottle helpers
Something Arjan suggested which allows us to clean up the code nicely

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 08:29:47 -07:00
Alan Cox f34d7a5b70 tty: The big operations rework
- Operations are now a shared const function block as with most other Linux
  objects

- Introduce wrappers for some optional functions to get consistent behaviour

- Wrap put_char which used to be patched by the tty layer

- Document which functions are needed/optional

- Make put_char report success/fail

- Cache the driver->ops pointer in the tty as tty->ops

- Remove various surplus lock calls we no longer need

- Remove proc_write method as noted by Alexey Dobriyan

- Introduce some missing sanity checks where certain driver/ldisc
  combinations would oops as they didn't check needed methods were present

[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 08:29:47 -07:00
Jason Wessel f2d937f3bf consoles: polling support, kgdboc
polled console handling support, to access a console in an irq-less
way while in debug or irq context.

absolutely zero impact as long as CONFIG_CONSOLE_POLL is disabled.
(which is the default)

[ jan.kiszka@siemens.com: lots of cleanups ]
[ mingo@elte.hu: redesign, splitups, cleanups. ]

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-17 20:05:37 +02:00
Paul Fulghum e10cc1df1d tty: add compat_ioctl
Add compat_ioctl method for tty code to allow processing of 32 bit ioctl
calls on 64 bit systems by tty core, tty drivers, and line disciplines.

Based on patch by Arnd Bergmann:
http://www.uwsg.iu.edu/hypermail/linux/kernel/0511.0/1732.html

[akpm@linux-foundation.org: make things static]
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11 08:29:35 -07:00
Alan Cox edc6afc549 [PATCH] tty: switch to ktermios and new framework
This is the core of the switch to the new framework.  I've split it from the
driver patches which are mostly search/replace and would encourage people to
give this one a good hard stare.

The references to BOTHER and ISHIFT are the termios values that must be
defined by a platform once it wants to turn on "new style" ioctl support.  The
code patches here ensure that providing

1. The termios overlays the ktermios in memory
2. The only new kernel only fields are c_ispeed/c_ospeed (or none)

the existing behaviour is retained.  This is true for the patches at this
point in time.

Future patches will define BOTHER, ISHIFT and enable newer termios structures
for each architecture, and once they are all done some of the ifdefs also
vanish.

[akpm@osdl.org: warning fix]
[akpm@osdl.org: IRDA fix]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 08:28:56 -08:00
Jeff Dike b68e31d0eb [PATCH] const struct tty_operations
As part of an SMP cleanliness pass over UML, I consted a bunch of
structures in order to not have to document their locking.  One of these
structures was a struct tty_operations.  In order to const it in UML
without introducing compiler complaints, the declaration of
tty_set_operations needs to be changed, and then all of its callers need to
be fixed.

This patch declares all struct tty_operations in the tree as const.  In all
cases, they are static and used only as input to tty_set_operations.  As an
extra check, I ran an i386 allyesconfig build which produced no extra
warnings.

53 drivers are affected.  I checked the history of a bunch of them, and in
most cases, there have been only a handful of maintenance changes in the
last six months.  serial_core.c was the busiest one that I looked at.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 07:57:14 -07:00
Greg Kroah-Hartman 331b831983 [PATCH] devfs: Rename TTY_DRIVER_NO_DEVFS to TTY_DRIVER_DYNAMIC_DEV
I've always found this flag confusing.  Now that devfs is no longer around, it
has been renamed, and the documentation for when this flag should be used has
been updated.

Also fixes all drivers that use this flag.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-06-26 12:25:09 -07:00
Greg Kroah-Hartman f4eaa37017 [PATCH] devfs: Remove the tty_driver devfs_name field as it's no longer needed
Also fixes all drivers that set this field.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-06-26 12:25:09 -07:00