HVC returns a size of -1 bytes for the write room in some cases.
This is bogus and not handled by the tty layer at all.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This has two outcomes:
* we give the TTY layer a tty_port
* we do not find the info structure every time open is called on that
  tty

Since we take a reference to a port in ->install, we need also
->cleanup to drop that reference.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: linuxppc-dev@lists.ozlabs.org
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A -next commit "TTY: HVC, use tty from tty_port" switched the driver
to use tty_port helper for tty refcounting. But it omitted to remove
manual tty refcounting from open, close and hangup. So now we are
getting random crashes caused by use-after-free:
Unable to handle kernel paging request for data at address 0xc0000003f9d550
Faulting instruction address: 0xc0000000001b7f40
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP: c0000000001b7f40 LR: c0000000001b7f14 CTR: c0000000000e04f0
...
NIP [c0000000001b7f40] .__kmalloc+0x70/0x230
LR [c0000000001b7f14] .__kmalloc+0x44/0x230
Call Trace:
[c0000003f68bf930] [c0000003f68bf9b0] 0xc0000003f68bf9b0 (unreliable)
[c0000003f68bf9e0] [c0000000001e5424] .alloc_fdmem+0x24/0x70
[c0000003f68bfa60] [c0000000001e54f8] .alloc_fdtable+0x88/0x130
[c0000003f68bfaf0] [c0000000001e5924] .dup_fd+0x384/0x450
[c0000003f68bfbd0] [c00000000009a310] .copy_process+0x880/0x11d0
[c0000003f68bfcd0] [c00000000009aee0] .do_fork+0x70/0x400
[c0000003f68bfdc0] [c0000000000141c4] .sys_clone+0x54/0x70
[c0000003f68bfe30] [c000000000009aa0] .ppc_clone+0x8/0xc

Fix that by complete removal of tty_kref_get/put in open/close/hangup
paths.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Reported-and-tested-by: NMichael Neuling <mikey@neuling.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: ppc-dev <linuxppc-dev@lists.ozlabs.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now, count is used from tty_port and protected by tty_port->lock.

n_outbuf is left unprotected in hvc_hangup now, because there is no
point to hold any lock, since other uses are unprotected too.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The driver already used refcounting. So we just switch it to tty_port
helpers. And switch to tty_port->lock for tty.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

And use kref from that. This means we need tty_port->ops->destruct to
properly free the structure. This is what destroy_hvc_struct used to
do so we leverage that.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

All num, magic and owner are set by alloc_tty_driver. No need to
re-set them on each allocation site.

pti driver sets something different to what it passes to
alloc_tty_driver. It is not a bug, since we don't use the lines
parameter in any way. Anyway this is fixed, and now we do the right
thing.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Acked-by: NTilman Schmidt <tilman@imap.cc>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 36116245.

It causes an infinite loop when booting Linux under Xen, as so:

  [    2.382984] console [hvc0] enabled
  [    2.382984] console [hvc0] enabled
  [    2.382984] console [hvc0] enabled
  ...

as reported by Konrad Rzeszutek Wilk.  And Rusty reports the same for
lguest.  He goes on to say:

   "This is not a concurrency problem: the issue seems to be that
    calling register_console() twice on the same struct console is a bad
    idea."

and Greg says he'll fix it up properly at some point later. Revert for now.
Reported-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: NRusty Russell <rusty@ozlabs.org>
Requested-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Miche Baker-Harvey <miche@google.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

printk only works for "registered consoles."  Currently, the hvc_console
code calls register_console() from hvc_instantiate(), but that's only
used in the early console case.  In hvc_alloc(), register_console() was
not called.

Add a call to register_console() in hvc_alloc(), set up the index in
the hvc_console, and set up the necessary vtermnos[] and cons_op[]
entries so that printk functions work.
Signed-off-by: NMiche Baker-Harvey <miche@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Let's use the newly added helper to avoid stalls in drivers which are
not yet ported to tty_port helpers.

Those which are broken (call tty_wait_until_sent with irqs disabled)
are left untouched. They are in a deeper trouble than we are trying to
solve here. This includes amiserial, 68328serial, 68360serial and
crisv10.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add poll_get_char and poll_put_char for kdb. Enable kdb at boot with:

kgdboc=hvc0

or at runtime with:

echo hvc0 > /sys/module/kgdboc/parameters/kgdboc
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Currently, the hvc_console_print() function drops console output if the
hvc backend's put_chars() returns 0.  This patch changes this behavior
to allow a retry through returning -EAGAIN.

This change also affects the hvc_push() function.  Both functions are
changed to handle -EAGAIN and to retry the put_chars() operation.

If a hvc backend returns -EAGAIN, the retry handling differs:

  - hvc_console_print() spins to write the complete console output.
  - hvc_push() behaves the same way as for returning 0.

Now hvc backends can indirectly control the way how console output is
handled through the hvc console layer.
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: NAnton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

On pseries machines, consoles are provided by the hypervisor using
a low level get_chars/put_chars type interface. However, this is
really just a transport to the service processor which implements
them either as "raw" console (networked consoles, HMC, ...) or as
"hvsi" serial ports.

The later is a simple packet protocol on top of the raw character
interface that is supposed to convey additional "serial port" style
semantics. In practice however, all it does is provide a way to
read the CD line and set/clear our DTR line, that's it.

We currently implement the "raw" protocol as an hvc console backend
(/dev/hvcN) and the "hvsi" protocol using a separate tty driver
(/dev/hvsi0).

However this is quite impractical. The arbitrary difference between
the two type of devices has been a major source of user (and distro)
confusion. Additionally, there's an additional mini -hvsi implementation
in the pseries platform code for our low level debug console and early
boot kernel messages, which means code duplication, though that low
level variant is impractical as it's incapable of doing the initial
protocol negociation to establish the link to the FSP.

This essentially replaces the dedicated hvsi driver and the platform
udbg code completely by extending the existing hvc_vio backend used
in "raw" mode so that:

 - It now supports HVSI as well
 - We add support for hvc backend providing tiocm{get,set}
 - It also provides a udbg interface for early debug and boot console

This is overall less code, though this will only be obvious once we
remove the old "hvsi" driver, which is still available for now. When
the old driver is enabled, the new code still kicks in for the low
level udbg console, replacing the old mini implementation in the platform
code, it just doesn't provide the higher level "hvc" interface.

In addition to producing generally simler code, this has several benefits
over our current situation:

 - The user/distro only has to deal with /dev/hvcN for the hypervisor
console, avoiding all sort of confusion that has plagued us in the past

 - The tty, kernel and low level debug console all use the same code
base which supports the full protocol establishment process, thus the
console is now available much earlier than it used to be with the
old HVSI driver. The kernel console works much earlier and udbg is
available much earlier too. Hackers can enable a hard coded very-early
debug console as well that works with HVSI (previously that was only
supported for the "raw" mode).

I've tried to keep the same semantics as hvsi relative to how I react
to things like CD changes, with some subtle differences though:

 - I clear DTR on close if HUPCL is set

 - Current hvsi triggers a hangup if it detects a up->down transition
   on CD (you can still open a console with CD down). My new implementation
   triggers a hangup if the link to the FSP is severed, and severs it upon
   detecting a up->down transition on CD.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

As requested by Arnd Bergmann, the hvc drivers are now
moved to the drivers/tty/hvc/ directory.  The virtio_console.c driver
was also moved, as it required the hvc_console.h file to be able to be
built, and it really is a hvc driver.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This doesn't do anything.

Cc: Timur Tabi <timur@freescale.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Amit Shah <amit.shah@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Kumar Gala <galak@gate.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sysrq operations do not accept tty argument anymore so no need to pass
it to us.

[Stephen Rothwell <sfr@canb.auug.org.au>: fix build breakage in drm code
 caused by sysrq using bool but not including linux/types.h]

[Sachin Sant <sachinp@in.ibm.com>: fix build breakage in s390 keyboadr
 driver]
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

The use of "hvc_con_driver" as the name for a file-static "struct
console" with a ".setup" field pointing to an __init function causes
a modpost warning, since a non-initdata structure points to init code.
Using "hvc_console" as the name triggers the hacky "*_console"
workaround in modpost to silence the warning, and is the same thing
that most of the other console drivers already do.

I made the same change in hvsi.c since I happened to notice it was
likely to suffer from the same problem.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

I don't claim to understand the tty layer, but it seems like hvc_open and
hvc_close should be balanced in their kref reference counting.

Right now we get a kref every call to hvc_open:

        if (hp->count++ > 0) {
                tty_kref_get(tty); <----- here
                spin_unlock_irqrestore(&hp->lock, flags);
                hvc_kick();
                return 0;
        } /* else count == 0 */

        tty->driver_data = hp;

        hp->tty = tty_kref_get(tty); <------ or here if hp->count was 0

But hvc_close has:

        tty_kref_get(tty);

        if (--hp->count == 0) {
...
                /* Put the ref obtained in hvc_open() */
                tty_kref_put(tty);
...
        }

        tty_kref_put(tty);

Since the outside kref get/put balance we only do a single kref_put when
count reaches 0.

The patch below changes things to call tty_kref_put once for every
hvc_close call, and with that my machine boots fine.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Acked-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

Alan pointed out a race in the code where hvc_remove is invoked. The
recent virtio_console work is the first user of hvc_remove().

Alan describes it thus:

The hvc_console assumes that a close and remove call can't occur at the
same time.

In addition tty_hangup(tty) is problematic as tty_hangup is asynchronous
itself....

So this can happen

        hvc_close                               hvc_remove
        hung up ? - no
                                                lock
                                                tty = hp->tty
                                                unlock
        lock
        hp->tty = NULL
        unlock
        notify del
        kref_put the hvc struct
        close completes
        tty is destroyed
                                                tty_hangup dead tty
                                                tty->ops will be NULL
                                                NULL->...

This patch adds some tty krefs and also converts to using tty_vhangup().
Reported-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: linuxppc-dev@ozlabs.org
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

vtermnos[] is unsigned, so this test was wrong.
Signed-off-by: NRoel Kluin <roel.kluin@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This is nicer for modern R/O protection.  And noone needs it non-const, so
constify the callers as well.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linuxppc-dev@ozlabs.org

Virtio consoles can be hotplugged, so hvc_alloc gets called from
multiple sites: from the initial probe() routine as well as later on
from workqueue handlers which aren't __devinit code.

So, drop the __devinit annotation for hvc_alloc.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This is nicer for modern R/O protection.  And noone needs it non-const, so
constify the callers as well.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The virtio console, which uses hvc, will get the ability to hot-unplug
ports. Export hvc_remove so that virtio_console can disassociate with
hvc.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Rename the locking free hvc_resize() function to __hvc_resize() and
provide an inline function that locks the hvc_struct and calls
__hvc_resize().

The rationale for this patch is that virtio_console calls the hvc_resize()
function without locking the hvc_struct. So it needs to call the lock
itself.

According to naming rules, the unlocked version is renamed and
prefixed with "__".
References to unlocked function calls in hvc back-ends has been updated.
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The result of container_of should not be NULL.  In particular, in this case
the argument to the enclosing function has passed though INIT_WORK, which
dereferences it, implying that its container cannot be NULL.

A simplified version of the semantic patch that makes this change is as
follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
identifier fn,work,x,fld;
type T;
expression E1,E2;
statement S;
@@

static fn(struct work_struct *work) {
  ... when != work = E1
  x = container_of(work,T,fld)
  ... when != x = E2
- if (x == NULL) S
  ...
}
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This function does not have an error return and returning an error is
instead interpreted as having a lot of pending bytes.

Reported by Jeff Harris who provided a list of some of the remaining
offenders.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch removes the tty->low_latency setting.

For irq based hvc_console backends the tty->low_latency must be set to 0,
because the tty_flip_buffer_push() function must not be called from IRQ context
(see drivers/char/tty_buffer.c).

For polled backends, the low_latency setting causes the bug trace below, because
tty_flip_buffer_push() is called within an atomic context and subsequent calls
might sleep due to mutex_lock.

BUG: sleeping function called from invalid context at /root/cvs/linux-2.6.git/kernel/mutex.c:207
in_atomic(): 1, irqs_disabled(): 0, pid: 748, name: khvcd
1 lock held by khvcd/748:
 #0:  (hvc_structs_lock){--..}, at: [<00000000002ceb50>] khvcd+0x58/0x12c
CPU: 0 Not tainted 2.6.29-rc1git #29
Process khvcd (pid: 748, task: 000000002fb9a480, ksp: 000000002f66bd78)
070000000000000a 000000002f66ba00 0000000000000002 (null)
       000000002f66baa0 000000002f66ba18 000000002f66ba18 0000000000104f08
       ffffffffffffc000 000000002f66bd78 (null) (null)
       000000002f66ba00 000000000000000c 000000002f66ba00 000000002f66ba70
       0000000000466af8 0000000000104f08 000000002f66ba00 000000002f66ba50
Call Trace:
([<0000000000104e7c>] show_trace+0x138/0x158)
 [<0000000000104f62>] show_stack+0xc6/0xf8
 [<0000000000105740>] dump_stack+0xb0/0xc0
 [<000000000013144a>] __might_sleep+0x14e/0x17c
 [<000000000045e226>] mutex_lock_nested+0x42/0x3b4
 [<00000000002c443e>] echo_char_raw+0x3a/0x9c
 [<00000000002c688c>] n_tty_receive_buf+0x1154/0x1208
 [<00000000002ca0a2>] flush_to_ldisc+0x152/0x220
 [<00000000002ca1da>] tty_flip_buffer_push+0x6a/0x90
 [<00000000002cea74>] hvc_poll+0x244/0x2c8
 [<00000000002ceb68>] khvcd+0x70/0x12c
 [<000000000015bbd0>] kthread+0x68/0xa0
 [<0000000000109d5a>] kernel_thread_starter+0x6/0xc
 [<0000000000109d54>] kernel_thread_starter+0x0/0xc
1 lock held by khvcd/748:
 #0:  (hvc_structs_lock){--..}, at: [<00000000002ceb50>] khvcd+0x58/0x12c
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Replace kmalloc() + memset()  with kzalloc().
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

hvc_console is setting low_latency unconditionally, but some clients are
interrupt driven and will call hvc_poll from irq context.  This will cause
tty_flip_buffer_push to be called from irq context, and it very clearly
states it must not be called from IRQ when low_latency is specified.

Looking back through history:
v2.6.16-rc1 via 33f0f88f
    [PATCH] TTY layer buffering revamp

added this new api.

v2.6.16-rc3 via 8977d929
    [PATCH] tty buffering stall fix

claims to fix a stall discovered with hvc_console

v2.6.16-rc5 via fb5c594c
   [PATCH] Fix race condition in hvc console.

said set this flag to avoid a stall problem, and was merged through
the powerpc arch tree.

Without searching for email discussions, it would appear to be an
overlapping "fix", but one that did not consider all users.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

I remember some history on this barrier.  There was a race between
open via /dev/console and the tty being fully setup.  Its also why
there is a temporary variable and the global is assigned at the end
of the function.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.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: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

this patch uses the new hvc callback hvc_resize to set the window size
which allows to change the tty size of hvc_console via a hvc_resize
function.

I have added a new feature bit VIRTIO_CONSOLE_F_SIZE. The driver will
change the window size on tty open and via the config_changed callback
of the transport. Currently lguest and kvm_s390 have not implemented this
callback, but the callback can be implemented at a later point in time.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The ctrl-o (^O) is a common control key used by several applications,
such as vim, but hvc_console uses ^O as the magic-sysrq key.  This
commit allows users to send ^O to applications by pressing ^O twice
in succession.

To implement this, this commit introduces a check if ^O is pressed
again if the sysrq_pressed variable is already set.  In this case,
clear sysrq_pressed state and flip the ^O character to the tty.  (The
old behavior has always set "sysrq_pressed" if ^O has been entered,
and it has not flipped the ^O character to the tty.)
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The test to check for a new winsize runs out-of-sync with the
underlying tty.  After a tty has been released and initialized again,
the winsize might differ between the tty and the hp struct.  The
solution is to simply remove the check and always schedule the resize
work.
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Removed __devexit annotation of hvc_remove() to avoid a section mismatch
if the backend initialization fails and hvc_remove() must be used to
clean up allocated hvc structs (called in section __init or __devinit).
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The patch provides the hvc_resize() function to update the terminal
window dimensions (struct winsize) for a specified hvc console.
The function stores the new window size and schedules a function
that finally updates the tty winsize and signals the change to
user space (SIGWINCH).
Because the winsize update must acquire a mutex and might sleep,
the function is scheduled instead of being called from hvc_poll()
or khvcd.

This patch uses the tty_do_resize() routine from the tty layer.
A pending resize work is canceled in hvc_close() and hvc_hangup().
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

If put_char() routine of a hvc console backend returns 0, then the
hvc console starts looping in the following scenarios:

1. hvc_console_print()
	If put_char() returns 0 then the while loop may loop forever.
	I have added the missing check for 0 to throw away console messages.

2. khvcd may loop:
	The thread calls hvc_poll() --> hvc_push()... if there are still
	buffered data then the HVC_POLL_WRITE bit is set and causes the
	khvcd thread to loop (if yield() returns immediately).

	However, instead of looping, the khvcd thread could sleep for
	MIN_TIMEOUT (doing the same as for get_chars()).
	The MIN_TIMEOUT is set if hvc_push() was not able to write
	data to the backend. If data has been written, the timeout is
	set to 0 to immediately re-schedule hvc_poll().
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> (virtio_console)
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

After a tty hangup() or close() operation, processes might not reset the
termio settings to a sane state. In order to reset the termios to its
default settings the tty driver flag TTY_DRIVER_RESET_TERMIOS has been added.

TTY driver flag description from include/linux/tty_driver.h:
	TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
	  termios setting when the last process has closed the device.
	  Used for PTY's, in particular.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>