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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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 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>
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>
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>
