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  1. 09 7月, 2010 1 次提交
  3. 08 4月, 2010 1 次提交
    • A
      hvc_console: Fix race between hvc_close and hvc_remove · 320718ee
      由 Anton Blanchard 提交于 
      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>
      320718ee
  5. 30 3月, 2010 1 次提交
    • T
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      由 Tejun Heo 提交于 
      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>
      5a0e3ad6
  7. 19 3月, 2010 1 次提交
    • A
      hvc_console: Fix race between hvc_close and hvc_remove · e74d098c
      由 Amit Shah 提交于 
      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>
      e74d098c
  9. 03 3月, 2010 1 次提交
  11. 24 2月, 2010 1 次提交
  13. 03 2月, 2010 2 次提交
  15. 08 12月, 2009 1 次提交
  17. 24 9月, 2009 1 次提交
  19. 20 8月, 2009 1 次提交
  21. 21 7月, 2009 1 次提交
  23. 16 1月, 2009 1 次提交
    • H
      hvc_console: Remove tty->low_latency · 7f8030d1
      由 Hendrik Brueckner 提交于 
      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>
      7f8030d1
  25. 13 1月, 2009 3 次提交
  27. 03 1月, 2009 1 次提交
  29. 30 12月, 2008 1 次提交
  31. 21 12月, 2008 1 次提交
    • H
      hvc_console: Escape magic sysrq key · 368c1e32
      由 Hendrik Brueckner 提交于 
      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>
      368c1e32
  33. 03 12月, 2008 1 次提交
  35. 22 10月, 2008 5 次提交
  37. 15 10月, 2008 1 次提交
    • C
      hvc_console: Fix free_irq in spinlocked section · eef2622a
      由 Christian Borntraeger 提交于 
          commit 611e097d
    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: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
      eef2622a
  39. 14 10月, 2008 1 次提交
    • J
      drivers/char/hvc_console.c: adjust call to put_tty_driver · 2571cd6a
      由 Julia Lawall 提交于 
      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: NJulia Lawall <julia@diku.dk>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2571cd6a
  41. 12 8月, 2008 1 次提交
    • C
      fix spinlock recursion in hvc_console · b1b135c8
      由 Christian Borntraeger 提交于 
      commit 611e097d
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: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      b1b135c8
  43. 25 7月, 2008 2 次提交
    • C
      virtio: console as a config option · 7721c494
      由 Christian Borntraeger 提交于 
      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: NRusty Russell <rusty@rustcorp.com.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      7721c494
    • C
      hvc_console: rework setup to replace irq functions with callbacks · 611e097d
      由 Christian Borntraeger 提交于 
      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: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      611e097d
  45. 14 5月, 2008 1 次提交
  47. 07 2月, 2008 1 次提交
  49. 25 1月, 2008 1 次提交
    • G
      kobject: convert hvc_console to use kref, not kobject · 12b20ded
      由 Greg Kroah-Hartman 提交于 
      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: NGreg Kroah-Hartman <gregkh@suse.de>
      12b20ded
  51. 17 10月, 2007 1 次提交
  53. 18 7月, 2007 1 次提交
    • R
      Freezer: make kernel threads nonfreezable by default · 83144186
      由 Rafael J. Wysocki 提交于 
      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: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NNigel 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      83144186
  55. 10 7月, 2007 1 次提交
  57. 09 5月, 2007 1 次提交
  59. 24 4月, 2007 2 次提交
  61. 27 2月, 2007 1 次提交