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: Anton Blanchard <anton@samba.org>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph 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: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Amit 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: Greg Kroah-Hartman <gregkh@suse.de>
vtermnos[] is unsigned, so this test was wrong.
Signed-off-by: Roel 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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: Amit Shah <amit.shah@redhat.com>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Benjamin 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: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Benjamin 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: Amit Shah <amit.shah@redhat.com>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Benjamin 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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Benjamin 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: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin 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: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus 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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Replace kmalloc() + memset() with kzalloc().
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin 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 33f0f88f1c
[PATCH] TTY layer buffering revamp
added this new api.
v2.6.16-rc3 via 8977d929e4
[PATCH] tty buffering stall fix
claims to fix a stall discovered with hvc_console
v2.6.16-rc5 via fb5c594c2a
[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: Benjamin 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: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin 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: Alan Cox <alan@redhat.com>
Signed-off-by: Linus 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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty 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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Paul 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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paul 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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin 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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin 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: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> (virtio_console)
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin 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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
I have added a hangup notifier that can be used by hvc console
backends to handle a tty hangup. The default irq hangup notifier
calls the notifier_del_irq() for compatibility.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
commit 611e097d77
Author: Christian Borntraeger <borntraeger@de.ibm.com>
hvc_console: rework setup to replace irq functions with callbacks
introduced a spinlock recursion problem. The notifier_del is
called with a lock held, and in turns calls free_irq which then
complains when manipulating procfs. This fixes it by moving the
call to the notifier to outside of the locked section.
Signed-off-by: Christian Borntraeger<borntraeger@de.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The call to put_tty_driver is out of place and is applied to the wrong
argument.
The function enclosing the patched code calls alloc_tty_driver and stores
the result in drv. Subsequently, there are two occurrences of error
handling code, one making a goto to put_tty and one making a goto to
stop_thread. At the point of the first one the assignment hvc_driver = drv
has not yet been executed, and from inspecting the rest of the file it
seems that hvc_driver would be NULL. Thus the current call to
put_tty_driver is useless, and one applied to drv is needed. The goto
stop_thread is in the error handling code for a call to
tty_register_driver, but the error cases in tty_register_driver do not free
its argument, so it should be done here. Thus, I have moved the put_tty
label after the stop_thread label, so that put_tty_driver is called in both
cases.
The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@r exists@
local idexpression x;
expression E,f;
position p1,p2,p3;
identifier l;
statement S;
@@
x = alloc_tty_driver@p1(...)
...
if (x == NULL) S
... when != E = x
when != put_tty_driver(x)
goto@p2 l;
... when != E = x
when != f(...,x,...)
when any
(
return \(0\|x\);
|
return@p3 ...;
)
@script:python@
p1 << r.p1;
p2 << r.p2;
p3 << r.p3;
@@
print "%s: call on line %s not freed or saved before return on line %s via line %s" % (p1[0].file,p1[0].line,p3[0].line,p2[0].line)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
commit 611e097d77
Author: Christian Borntraeger <borntraeger@de.ibm.com>
hvc_console: rework setup to replace irq functions with callbacks
introduced a spinlock recursion problem.
request_irq tries to call the handler if the IRQ is shared.
The irq handler of hvc_console calls hvc_poll and hvc_kill
which might take the hvc_struct spinlock. Therefore, we have
to call request_irq outside the spinlock.
We can move the notifier_add safely outside the spinlock as ->data must
not be changed by the backend. Otherwise, tty_hangup would fail anyway.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I also added a small Kconfig change that allows the user to specify the
virtio console in menuconfig.
(Fixes to export symbols from Stephen Rothwell <sfr@canb.auug.org.au>)
(Fixes for CONFIG_VIRTIO_CONSOLE=y vs CONFIG_VIRTIO=m from Christian himself)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
This patch tries to change hvc_console to not use request_irq/free_irq if
the backend does not use irqs. This allows virtio_console to use hvc_console
without having a linker reference to request_irq/free_irq.
In addition, together with patch 2/3 it improves the performance for virtio
console input. (an earlier version of this patch was tested by Yajin on lguest)
The irq specific code is moved to hvc_irq.c and selected by the drivers that
use irqs (System p, System i, XEN).
I replaced "int irq" with the opaque "int data". The request_irq and
free_irq calls are replaced with notifier_add and notifier_del. I have also
changed the code a bit to call the notifier_add and notifier_del inside the
spinlock area as the callbacks are found via hp->ops.
Changes since last version:
o remove ifdef
o reintroduce "irq_requested" as "notified"
o cleanups, sparse..
I did not move the timer based polling into a separate polling scheme. I
played with several variants, but it seems we need to sleep/schedule in
a thread even for irq based consoles, as there are throttleing and buffer
size constraints.
I also kept hvc_struct defined in hvc_console.h so that hvc_irq.c can access
the irq_requested element.
Feedback is appreciated. virtio_console is currently the only available console
for kvm on s390. I plan to push this change as soon as all affected parties
agree on it. I would love to get test results from System p, Xen etc.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is a little messier than I'd like because xmon.h only exists
on powerpc and we can't have a static inline and an extern declaration
visible at the same time.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
single list_head variable initialized with LIST_HEAD_INIT could almost
always can be replaced with LIST_HEAD declaration, this shrinks the code
and looks better.
Signed-off-by: Denis Cheng <crquan@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hvc_console is using a kobject only for reference counting, nothing
else. So switch it to use a kref instead, which is all that is needed,
and is much smaller.
Cc: Anton Blanchard <anton@au.ibm.com>
Cc: Paul Mackerras <paulus@au.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ryan S. Arnold <rsa@us.ibm.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This changes hvc_init() to be called only when someone actually uses the
hvc_console driver. Dave Jones complained when profiling bootup.
hvc_console used to only be for Power aka pSeries: now lguest and Xen both
want it built-in in case the kernel is a guest under one of those, even
though usually it will be a native boot.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves. This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.
It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.
The patch causes all kernel threads to be nonfreezable by default (ie. to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE. It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear. Additionally, it updates documentation to
describe the freezing of tasks more accurately.
[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- make needlessly global code static
- remove the unused EXPORT_SYMBOL's
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix a handful of comment typos for hvc_console.
Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add a back-off mechanism to hvc_console's polling logic. This change
drops the timers/second ratio from ~90 to ~1/2 while the console is
idle.
This change is most noticeable when watching /proc/timer_stats output.
This only affects when the hvc_console is running in poll mode, i.e.
power4 and cell systems.
I've tested on Power4, Michael Ellerman has both contributed to the
patch and tested on cell.
Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Paulus preferred this over #defining NO_IRQ in the file, since that's
0 for powerpc anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move process freezing functions from include/linux/sched.h to freezer.h, so
that modifications to the freezer or the kernel configuration don't require
recompiling just about everything.
[akpm@osdl.org: fix ueagle driver]
Signed-off-by: Nigel Cunningham <nigel@suspend2.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
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>
No other tty driver will print on the console when the open of it fails.
On systems that happen to be configured for both ttyS0 and hvc0 console,
this will keep flooding the console output. This is most likely to
happen with systems booted between with and without hypervisor from the
same filesystem.
Let's just remove it. When it's really needed (i.e. when the open fails
and someone is trying to debug it), noone will see the output anyway. And
init will report the opens failing in due time through the syslog.
Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Ryan S. Arnold <rsa@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
So the iSeries console will be faster since it can send up to 200 bytes at
a time to the Hypervisor. This only affects the tty part of the console,
the console writes are still in 16 byte lots.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Currently the hvc_rtas driver is painfully slow to use. Our "benchmark" is
ls -R /etc, which spits out about 27866 characters. The theoretical maximum
speed would be about 2.2 seconds, the current code takes ~50 seconds.
The core of the problem is that sometimes when the tty layer asks us to push
characters the firmware isn't able to handle some or all of them, and so
returns an error. The current code sees this and just returns to the tty code
with the buffer half sent.
The khvcd thread will eventually wake up and try to push more characters, which
will usually work because by then the firmware's had time to make room. But
the khvcd thread only wakes up every 10 milliseconds, which isn't fast enough.
So change the khvcd thread logic so that if there's an incomplete write we
yield() and then immediately try writing again. Doing so makes POLL_QUICK and
POLL_WRITE synonymous, so remove POLL_QUICK.
With this patch our "benchmark" takes ~2.8 seconds.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
