There are several pretty much unfixable races in the old ldisc code, especially
with respect to pty behaviour and also to hangup. It's easier to rewrite the
code than simply try and patch it up.
This patch
- splits the ldisc from the tty (so we will be able to refcount it more cleanly
later)
- introduces a mutex lock for ldisc changing on an active device
- fixes the complete mess that hangup caused
- implements hopefully correct setldisc/close/hangup locking
There are still some problems around pty pairs that have always been there but
at least it is now possible to understand the code and fix further problems.
This fixes the following known bugs
- hang up can leak ldisc references
- hang up may not call open/close on ldisc in a matched way
- pty/tty pairs can deadlock during an ldisc change
- reading the ldisc proc files can cause every ldisc to be loaded
and probably a few other of the mysterious ldisc race reports.
I'm sure it also adds the odd new one.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before trying to tackle the ldisc bugs the code needs to be a good deal
more readable, so do the simple extractions of routines first.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need this for devices that cannot flush and wait, but which do not order
data and modem events. Without it we will hang up before all the data
clears the hardware. Needed for the USB changes.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some drivers implement this internally, others miss it out. Push the
behaviour into the core code as that way everyone will do it consistently.
Update the dtr rts method to raise or lower depending upon flags. Having a
single method in this style fits most of the implementations more cleanly than
two funtions.
We need this in place before we tackle the USB side
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Again this is a lot of common code we can unify
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Start sucking more commonality out of the drivers into a single piece of
core code.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This helps set the basis for moving block_til_ready into common code. We also
introduce a tty_port_hangup helper as this will also be generally needed.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This moves another per device special out of what should be shared open
wait paths into private methods
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the first step to generalising the various pieces of waiting logic
duplicated in all sorts of serial drivers.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Fixes the loss of echoed (and other ldisc-generated characters) when
the tty is stopped or when the driver output buffer is full (happens
frequently for input during continuous program output, such as ^C)
and removes the Big Kernel Lock from the N_TTY line discipline.
Adds an "echo buffer" to the N_TTY line discipline that handles all
ldisc-generated output (including echoed characters). Along with the
loss of characters, this also fixes the associated loss of sync between
tty output and the ldisc state when characters cannot be immediately
written to the tty driver.
The echo buffer stores (in addition to characters) state operations that need
to be done at the time of character output (like management of the column
position). This allows echo to cooperate correctly with program output,
since the ldisc state remains consistent with actual characters written.
Since the echo buffer code now isolates the tty column state code
to the process_out* and process_echoes functions, we can remove the
Big Kernel Lock (BKL) and replace it with mutex locks.
Highlights are:
* Handles echo (and other ldisc output) when tty driver buffer is full
- continuous program output can block echo
* Saves echo when tty is in stopped state (e.g. ^S)
- (e.g.: ^Q will correctly cause held characters to be released for output)
* Control character pairs (e.g. "^C") are treated atomically and not
split up by interleaved program output
* Line discipline state is kept consistent with characters sent to
the tty driver
* Remove the big kernel lock (BKL) from N_TTY line discipline
Signed-off-by: Joe Peterson <joe@skyrush.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (241 commits)
sched, trace: update trace_sched_wakeup()
tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3
Revert "x86: disable X86_PTRACE_BTS"
ring-buffer: prevent false positive warning
ring-buffer: fix dangling commit race
ftrace: enable format arguments checking
x86, bts: memory accounting
x86, bts: add fork and exit handling
ftrace: introduce tracing_reset_online_cpus() helper
tracing: fix warnings in kernel/trace/trace_sched_switch.c
tracing: fix warning in kernel/trace/trace.c
tracing/ring-buffer: remove unused ring_buffer size
trace: fix task state printout
ftrace: add not to regex on filtering functions
trace: better use of stack_trace_enabled for boot up code
trace: add a way to enable or disable the stack tracer
x86: entry_64 - introduce FTRACE_ frame macro v2
tracing/ftrace: add the printk-msg-only option
tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()
x86, bts: correctly report invalid bts records
...
Fixed up trivial conflict in scripts/recordmcount.pl due to SH bits
being already partly merged by the SH merge.
AUDIT_TTY records currently log all data read by processes marked for
TTY input auditing, even if the data was "pushed back" using the TIOCSTI
ioctl, not typed by the user.
This patch records all TIOCSTI calls to disambiguate the input. It
generates one audit message per character pushed back; considering
TIOCSTI is used very rarely, this simple solution is probably good
enough. (The only program I could find that uses TIOCSTI is mailx/nail
in "header editing" mode, e.g. using the ~h escape. mailx is used very
rarely, and the escapes are used even rarer.)
Signed-Off-By: Miloslav Trmac <mitr@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>
Stephen Rothwell reported tht this warning started triggering in
linux-next:
In file included from init/main.c:27:
include/linux/tty.h: In function ‘tty_kref_get’:
include/linux/tty.h:330: warning: ‘______f’ is static but declared in inline function ‘tty_kref_get’ which is not static
Which gcc emits for 'extern inline' functions that nevertheless define
static variables. Change it to 'static inline', which is the norm
in the kernel anyway.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Move the set up on ldisc change into the ldisc
Move the INQ/OUTQ cases into the driver not in shared ioctl code where it
gives bogus answers for other ldisc values
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The majority of the remaining init_dev code is pty special cases. We
refactor this code into the driver->install method.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original suggestion and proposal from Sukadev Bhattiprolu.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Carry on pushing code out of tty_io when it belongs to other drivers. I'm
not 100% happy with some of this and it will be worth revisiting some of the
exports later when the restructuring work is done.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
We now have the infrastructure to sort this out but rather than teaching
the syscall tty lock rules we move the hard work into a tty helper
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.
Contains two err->dev_err changes merged together to fix clashes in the
-next tree.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Introduce a kref to the tty structure and use it to protect the tty->signal
tty references. For now we don't introduce it for anything else.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new line discipline for "pulse per second" devices connected to
a serial port.
Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The two are basically independent chunks of code so lets split them up for
readability and sanity. It also makes the API boundaries much clearer.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Every tty driver has its own concept of a port structure and because
they all differ we cannot extract commonality. Begin fixing this by
creating a structure drivers can elect to use so that over time we can
push fields into this and create commonality and then introduce common
methods.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Although if people have questions about ARCnet, perhaps it's _better_
for them to be mailing dwmw2@cam.ac.uk about it...
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
- 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>
This fixes the last couple of pid struct locking failures I know about.
[oleg@tv-sign.ru: clean up do_task_stat()]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Historically tty->pgrp and friends were pid_t and the code "knew" they were
safe. The change to pid structs opened up a few races and the removal of the
BKL in places made them quite hittable. We put tty->pgrp under the ctrl_lock
for the tty.
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Push the BKL down into the line disciplines
- Switch the tty layer to unlocked_ioctl
- Introduce a new ctrl_lock spin lock for the control bits
- Eliminate much of the lock_kernel use in n_tty
- Prepare to (but don't yet) call the drivers with the lock dropped
on the paths that historically held the lock
BKL now primarily protects open/close/ldisc change in the tty layer
[jirislaby@gmail.com: a couple of fixes]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the code that automatically disables TTY input auditing in processes
that open TTYs when they have no other TTY open; this heuristic was
intended to automatically handle daemons, but it has false positives (e.g.
with sshd) that make it impossible to control TTY input auditing from a PAM
module. With this patch, TTY input auditing is controlled from user-space
only.
On the other hand, not even for daemons does it make sense to audit "input"
from PTY masters; this data was produced by a program writing to the PTY
slave, and does not represent data entered by the user.
Signed-off-by: Miloslav Trmac <mitr@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Previously I added sessionid output to all audit messages where it was
available but we still didn't know the sessionid of the sender of
netlink messages. This patch adds that information to netlink messages
so we can audit who sent netlink messages.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This legacy define from the old buffer code is now only used in a single
power pc driver than doesn't compile anyway.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I couldn't find any users, so removing it..
Signed-off-by: Daniel Walker <dwalker@mvista.com>
Acked-by: Alan Cox <alan@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds a protocol/address family number, ARP hardware type,
ethernet packet type, and a line discipline number for the SocketCAN
implementation.
Signed-off-by: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
Signed-off-by: Urs Thuermann <urs.thuermann@volkswagen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cleaning out all the incorrect 'no change made' checks for termios
settings showed up a problem with the PL2303. The hardware here seems to
lose sync and bits if you tell it to make no changes. This shows up with
a real world application.
To fix this the driver check for meaningful hardware changes is restored
but doing the tests correctly and as a tty layer function so it doesn't
get duplicated wrongly everywhere if other drivers turn out to need it.
Signed-off-by: Alan Cox <alan@redhat.com>
Tested-by: Mirko Parthey <mirko.parthey@informatik.tu-chemnitz.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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: Alan Cox <alan@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This adds three new functions (or in one case to be more exact makes it
always available)
tty_termios_copy_hw
Copies all the hardware settings from one termios structure to the other.
This is intended for drivers that support little or no hardware setting
tty_termios_encode_baud_rate
Allows you to set the input and output baud rate in a termios structure. A
driver is supposed to set the resulting baud rate from a request so most
will want to use this function to set the resulting input and output rates
to match the hardware values. Internally it knows about keeping Bxxx
encoding when possible to maximise compatibility.
tty_encode_baud_rate
As above but for the tty's own current termios structure
I suspect this will initially need some tweaking as it gets enabled by
driver patches over the next few mm cycles so consider this lot -mm only
for the moment so it can stabilize and end up neat before it goes to base.
I've tried not to break any obscure architectures - if you get a speed you
can't represent the code will print warnings on non updated termios systems
but not break.
Once this is merged and seems sane I've got a growing pile of driver
updates to use it - notably for USB serial drivers.
[akpm@linux-foundation.org: cleanups]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No longer used. TTY_FLIPBUF_SIZE will also go soon but needs a couple of
other cleanups first
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch c5c34d4862 (tty: flush flip buffer on
ldisc input queue flush) introduces a race condition which can lead to memory
leaks.
The problem can be triggered when tcflush() is called when data are being
pushed to the line discipline driver by flush_to_ldisc().
flush_to_ldisc() releases tty->buf.lock when calling the line discipline
receive_buf function. At that poing tty_buffer_flush() kicks in and sets both
tty->buf.head and tty->buf.tail to NULL. When flush_to_ldisc() finishes, it
restores tty->buf.head but doesn't touch tty->buf.tail. This corrups the
buffer queue, and the next call to tty_buffer_request_room() will allocate a
new buffer and overwrite tty->buf.head. The previous buffer is then lost
forever without being released.
(Thanks to Laurent for the above text, for finding, disgnosing and reporting
the bug)
- Use tty->flags bits for the flush status.
- Wait for the flag to clear again before returning
- Fix the doc error noted
- Fix flush of empty queue leaving stale flushpending
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Paul Fulghum <paulkf@microgate.com>
Cc: Laurent Pinchart <laurentp@cse-semaphore.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add TTY input auditing, used to audit system administrator's actions. This is
required by various security standards such as DCID 6/3 and PCI to provide
non-repudiation of administrator's actions and to allow a review of past
actions if the administrator seems to overstep their duties or if the system
becomes misconfigured for unknown reasons. These requirements do not make it
necessary to audit TTY output as well.
Compared to an user-space keylogger, this approach records TTY input using the
audit subsystem, correlated with other audit events, and it is completely
transparent to the user-space application (e.g. the console ioctls still
work).
TTY input auditing works on a higher level than auditing all system calls
within the session, which would produce an overwhelming amount of mostly
useless audit events.
Add an "audit_tty" attribute, inherited across fork (). Data read from TTYs
by process with the attribute is sent to the audit subsystem by the kernel.
The audit netlink interface is extended to allow modifying the audit_tty
attribute, and to allow sending explanatory audit events from user-space (for
example, a shell might send an event containing the final command, after the
interactive command-line editing and history expansion is performed, which
might be difficult to decipher from the TTY input alone).
Because the "audit_tty" attribute is inherited across fork (), it would be set
e.g. for sshd restarted within an audited session. To prevent this, the
audit_tty attribute is cleared when a process with no open TTY file
descriptors (e.g. after daemon startup) opens a TTY.
See https://www.redhat.com/archives/linux-audit/2007-June/msg00000.html for a
more detailed rationale document for an older version of this patch.
[akpm@linux-foundation.org: build fix]
Signed-off-by: Miloslav Trmac <mitr@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Paul Fulghum <paulkf@microgate.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Without this a tty write could block if a previous blocking tty write was
in progress on the same tty and blocked by a line discipline or hardware
event. Originally found and reported by Dave Johnson.
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Dave Johnson <djohnson+linux-kernel@sw.starentnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While researching the tty layer pid leaks I found a weird case in selinux when
we drop a controlling tty because of inadequate permissions we don't do the
normal hangup processing. Which is a problem if it happens the session leader
has exec'd something that can no longer access the tty.
We already have code in the kernel to handle this case in the form of the
TIOCNOTTY ioctl. So this patch factors out a helper function that is the
essence of that ioctl and calls it from the selinux code.
This removes the inconsistency in handling dropping of a controlling tty and
who knows it might even make some part of user space happy because it received
a SIGHUP it was expecting.
In addition since this removes the last user of proc_set_tty outside of
tty_io.c proc_set_tty is made static and removed from tty.h
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Of kernel subsystems that work with pids the tty layer is probably the largest
consumer. But it has the nice virtue that the assiation with a session only
lasts until the session leader exits. Which means that no reference counting
is required. So using struct pid winds up being a simple optimization to
avoid hash table lookups.
In the long term the use of pid_nr also ensures that when we have multiple pid
spaces mixed everything will work correctly.
Signed-off-by: Eric W. Biederman <eric@maxwell.lnxi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every call to is_orphaned_pgrp passed in process_group(current) which is racy
with respect to another thread changing our process group. It didn't bite us
because we were dealing with integers and the worse we would get would be a
stale answer.
In switching the checks to use struct pid to be a little more efficient and
prepare the way for pid namespaces this race became apparent.
So I simplified the calls to the more specialized is_current_pgrp_orphaned so
I didn't have to worry about making logic changes to avoid the race.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The aim of this patch set is to start wrapping up the struct pid conversions.
As such this patchset culminates with the removal of kill_pg, kill_pg_info,
__kill_pg_info, do_each_task_pid, and while_each_task_pid.
kill_proc, daemonize, and kernel_thread are still in my sights but there is
still work to get to them.
The first three are basic cleanups around disassociate_ctty, while working on
converting it I found several issues. tty_old_pgrp can be a tricky concept to
wrap your head around.
1 tty: Make __proc_set_tty static.
2 tty: Clarify disassociate_ctty
3 tty: Fix the locking for signal->session in disassociate_ctty
These just stop using the old helper functions.
4 signal: Use kill_pgrp not kill_pg in the sunos compatibility code.
5 signal: Rewrite kill_something_info so it uses newer helpers.
Then the grind to convert the tty layer and all of it's helper functions to
struct pid.
6 pid: Make session_of_pgrp use struct pid instead of pid_t.
7 pid: Use struct pid for talking about process groups in exit.c
8 pid: Replace is_orphaned_pgrp with is_current_pgrp_orphaned
9 tty: Update the tty layer to work with struct pid.
A final helper function update.
10 pid: Replace do/while_each_task_pid with do/while_each_pid_task
And the removal of the functions that are now unused.
11 pid: Remove now unused do_each_task_pid and while_each_task_pid
12 pid: Remove the now unused kill_pg kill_pg_info and __kill_pg_info
All of these should be fairly simple and to the point.
This patch:
Currently all users of __proc_set_tty are in tty_io.c so make the function
static.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The line discipline numbers N_* are currently defined for each architecture
individually, but (except for a seeming mistake) identically, in
asm/termios.h. There is no obvious reason why these numbers should be
architecture specific, nor any apparent relationship with the termios
structure. The total number of these, NR_LDISCS, is defined in linux/tty.h
anyway. So I propose the following patch which moves the definitions of
the individual line disciplines to linux/tty.h too.
Three of these numbers (N_MASC, N_PROFIBUS_FDL, and N_SMSBLOCK) are unused
in the current kernel, but the patch still keeps the complete set in case
there are plans to use them yet.
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This does several things.
- It moves looking up of the current foreground console into process
context where we can safely take the semaphore that protects this
operation.
- It uses the new flavor of work queue processing.
- This generates a factor of do_SAK, __do_SAK that runs immediately.
- This calls __do_SAK with the console semaphore held ensuring nothing
else happens to the console while we process the SAK operation.
- With the console SAK processing moved into process context this
patch removes the xchg operations that I used to attempt to attomically
update struct pid, because of the strange locking used in the SAK processing.
With SAK using the normal console semaphore nothing special is needed.
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Fix the locking of signal->tty.
Use ->sighand->siglock to protect ->signal->tty; this lock is already used
by most other members of ->signal/->sighand. And unless we are 'current'
or the tasklist_lock is held we need ->siglock to access ->signal anyway.
(NOTE: sys_unshare() is broken wrt ->sighand locking rules)
Note that tty_mutex is held over tty destruction, so while holding
tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys
are governed by their open file handles. This leaves some holes for tty
access from signal->tty (or any other non file related tty access).
It solves the tty SLAB scribbles we were seeing.
(NOTE: the change from group_send_sig_info to __group_send_sig_info needs to
be examined by someone familiar with the security framework, I think
it is safe given the SEND_SIG_PRIV from other __group_send_sig_info
invocations)
[schwidefsky@de.ibm.com: 3270 fix]
[akpm@osdl.org: various post-viro fixes]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Alan Cox <alan@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Conflicts:
drivers/infiniband/core/iwcm.c
drivers/net/chelsio/cxgb2.c
drivers/net/wireless/bcm43xx/bcm43xx_main.c
drivers/net/wireless/prism54/islpci_eth.c
drivers/usb/core/hub.h
drivers/usb/input/hid-core.c
net/core/netpoll.c
Fix up merge failures with Linus's head and fix new compilation failures.
Signed-Off-By: David Howells <dhowells@redhat.com>
Converts from using struct "class_device" to "struct device" making
everything show up properly in /sys/devices/ with symlinks from the
/sys/class directory.
Also fixes up the isdn drivers that were putting something in the class
device's directory.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Separate delayable work items from non-delayable work items be splitting them
into a separate structure (delayed_work), which incorporates a work_struct and
the timer_list removed from work_struct.
The work_struct struct is huge, and this limits it's usefulness. On a 64-bit
architecture it's nearly 100 bytes in size. This reduces that by half for the
non-delayable type of event.
Signed-Off-By: David Howells <dhowells@redhat.com>
Create a new header file, fs/internal.h, for common definitions local to the
sources in the fs/ directory.
Move extern definitions that should be in header files from fs/*.c to
fs/internal.h or other main header files where they span directories.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[akpm@osdl.org: fix]
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Unlike the other tty comment patch this one has code changes. Specifically
it limits the queue size for a tty to 64K characters (128Kbytes) worst case
even if the tty is ignoring tty->throttle. This is because certain drivers
don't honour the throttle value correctly, although it is a useful
safeguard anyway.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
screen_info.h doesn't have anything to do with the tty layer and shouldn't be
included by tty.h. This patches removes the include and modifies all users to
directly include screen_info.h. struct screen_info is mainly used to
communicate with the console drivers in drivers/video/console. Note that this
patch touches every arch and I have no way of testing it. If there is a
mistake the worst thing that will happen is a compile error.
[akpm@osdl.org: fix arm build]
[akpm@osdl.org: fix alpha build]
Signed-off-by: Jon Smirl <jonsmir@gmail.com>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
MAX_NR_CONSOLES, fg_console, want_console and last_console are more of a
function of the VT layer than the TTY one. Moving these to vt.h and vt_kern.h
allows all of the framebuffer and VT console drivers to remove their
dependency on tty.h.
[akpm@osdl.org: fix alpha build]
Signed-off-by: Jon Smirl <jonsmir@gmail.com>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove 'active' field from tty buffer structure. This was added in 2.6.16
as part of a patch to make the new tty buffering SMP safe. This field is
unnecessary with the more intelligently written flush_to_ldisc that adds
receive_room handling.
Removing this field reverts to simpler logic where the tail buffer is
always the 'active' buffer, which should not be freed by flush_to_ldisc.
(active == buffer being filled with new data)
The result is simpler, smaller, and faster tty buffer code.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove TTY_DONT_FLIP tty flag. This flag was introduced in 2.1.X kernels
to prevent the N_TTY line discipline functions read_chan() and
n_tty_receive_buf() from running at the same time. 2.2.15 introduced
tty->read_lock to protect access to the N_TTY read buffer, which is the
only state requiring protection between these two functions.
The current TTY_DONT_FLIP implementation is broken for SMP, and is not
universally honored by drivers that send data directly to the line
discipline receive_buf function.
Because TTY_DONT_FLIP is not necessary, is broken in implementation, and is
not universally honored, it is removed.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Let tty_register_device() return a pointer to the class device it creates.
This allows registrants to add their own sysfs files under the class
device node.
Signed-off-by: Hansjoerg Lipp <hjlipp@web.de>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Prevent stalled processing of received data when a driver allocates tty
buffer space but does not immediately follow the allocation with more data
and a call to schedule receive tty processing. (example: hvc_console) This
bug was introduced by the first locking patch for the new tty buffering.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Change locking in the new tty buffering facility from using tty->read_lock,
which is currently ignored by drivers and thus ineffective. New locking
uses a new tty buffering specific lock enforced centrally in the tty
buffering code.
Two drivers (esp and cyclades) are updated to use the tty buffering
functions instead of accessing tty buffering internals directly. This is
required for the new locking to work.
Minor checks for NULL buffers added to
tty_prepare_flip_string/tty_prepare_flip_string_flags
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.
This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.
When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.
For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).
Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.
The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.
I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.
Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real. That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.
Description:
tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification]. It
does now also return the number of chars inserted
There are also
tty_buffer_request_room(tty, len)
which asks for a buffer block of the length requested and returns the space
found. This improves efficiency with hardware that knows how much to
transfer.
and tty_insert_flip_string_flags(tty, str, flags, len)
to insert a string of characters and flags
For a smart interface the usual code is
len = tty_request_buffer_room(tty, amount_hardware_says);
tty_insert_flip_string(tty, buffer_from_card, len);
More description!
At the moment tty buffers are attached directly to the tty. This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)
I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers. This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.
So far so good. Lots of drivers reference tty->flip.*. Several of them also
call directly and unsafely into function pointers it provides. This will all
break. Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.
At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say
int tty_buffer_request_room(tty, size)
Try and ensure at least size bytes are available, returns actual room (may be
zero). At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative. (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space. The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.
int tty_insert_flip_char(tty, ch, flag)
As before insert a character if there is room. Now returns 1 for success, 0
for failure.
int tty_insert_flip_string(tty, str, len)
Insert a block of non error characters. Returns the number inserted.
int tty_prepare_flip_string(tty, strptr, len)
Adjust the buffer to allow len characters to be added. Returns a buffer
pointer in strptr and the length available. This allows for hardware that
needs to use functions like insl or mencpy_fromio.
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This makes it possible for boot code to use screen_info without dragging in
all of tty.h.
Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add rudimentary support by manipulating the VGA registers. However, not
all vesa modes are VGA compatible, so VGA compatiblity is checked first.
Only 2 levels are supported, powerup and powerdown.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
It's a bit strange to see tty_register_ldisc call in modules' exit
functions.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
