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  1. Nov 03, 2009
  3. Oct 30, 2009
  5. Oct 22, 2009
  7. Oct 14, 2009
    • Andreas Schwab's avatar
      tty: fix vt_compat_ioctl · 4b1fe779
      Andreas Schwab authored 
      

Call compat_unimap_ioctl, not do_unimap_ioctl.

This was broken by commit e9216651.

The compat_unimap_ioctl was originally called do_unimap_ioctl in
fs/compat_ioctl.h which got moved to drivers/char/vt_ioctl.c.
In that patch, the caller was not updated and consequently called
the native handler.

Signed-off-by: default avatarAndreas Schwab <schwab@linux-m68k.org>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      4b1fe779
    • Linus Torvalds's avatar
      tty: use the new 'flush_delayed_work()' helper to do ldisc flush · 97ad5a03
      Linus Torvalds authored 
      

This way all flush_to_ldisc work is always done through the workqueues,
and we thus have a single point of serialization.  It also means that we
can avoid calling flush_to_ldisc() entirely if there was no delayed work
pending.

[ Side note: using workqueues and keventd as the single way to enter
  flush_to_ldisc() still doesn't absolutely guarantee that we can't have
  concurrency: keventd is multithreaded and has a thread per CPU, and
  while the WORK_STRUCT_PENDING bit guarantees a single work only being
  on the pending list once, the work might be both pending and _running_
  at the same time. Workqueues are not simple. ]

This was also confirmed to fix bugzilla #14388, even without the earlier
locking fix and cleanup (commit c8e33141: "tty: Make flush_to_ldisc()
locking more robust").  So both commits fix the same bug differently,
and either would have worked on its own.  But I'm committing them both
since they are cleanups independent of each other.

Reported-and-tested-by: default avatarBoyan <btanastasov@yahoo.co.uk>
Acked-by: default avatarAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      97ad5a03
    • Linus Torvalds's avatar
      tty: Make flush_to_ldisc() locking more robust · c8e33141
      Linus Torvalds authored 
      The locking logic in this function is extremely subtle, and it broke
when we started doing potentially concurrent 'flush_to_ldisc()' calls in
commit e043e42b ("pty: avoid forcing
'low_latency' tty flag").

The code in flush_to_ldisc() used to set 'tty->buf.head' to NULL, with
the intention that this would then cause any other concurrent calls to
not do anything (locking note: we have to drop the buf.lock over the
call to ->receive_buf that can block, which is why we can have
concurrency here at all in the first place).

It also used to set the TTY_FLUSHING bit, which would then cause any
concurrent 'tty_buffer_flush()' to not free all the tty buffers and
clear 'tty->buf.tail'.  And with 'buf.head' being NULL, and 'buf.tail'
being non-NULL, new data would never touch 'buf.head'.

Does that sound a bit too subtle? It was.  If another concurrent call to
'flush_to_ldisc()' were to come in, the NULL buf.head would indeed cause
it to not process the buffer list, but it would still clear TTY_FLUSHING
afterwards, making the buffer protection against 'tty_buffer_flush()' no
longer work.

So this clears it all up.  We depend purely on TTY_FLUSHING for handling
re-entrancy, and stop playing games with the buffer list entirely.  In
fact, the buffer list handling is now robust enough that we could
probably stop doing the whole "protect against 'tty_buffer_flush()'"
thing entirely.

However, Alan also points out that we would probably be better off
simplifying the locking even further, and just take the tty ldisc_mutex
around all the buffer flushing calls.  That seems like a good idea, but
in the meantime this is a conceptually minimal fix (with the patch
itself being bigger than required just to clean the code up and make it
readable).

This fixes keyboard trouble under X:

	http://bugzilla.kernel.org/show_bug.cgi?id=14388



Reported-and-tested-by: default avatarFrédéric Meunier <fredlwm@gmail.com>
Reported-and-tested-by: default avatarBoyan <btanastasov@yahoo.co.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c8e33141
    • Linus Torvalds's avatar
      tty: use the new 'flush_delayed_work()' helper to do ldisc flush · 514fc01d
      Linus Torvalds authored 
      

This way all flush_to_ldisc work is always done through the workqueues,
and we thus have a single point of serialization.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      514fc01d
    • Linus Torvalds's avatar
      Make flush_to_ldisc properly handle parallel calls · 45242006
      Linus Torvalds authored
      45242006
  9. Oct 13, 2009
  11. Oct 11, 2009
  13. Oct 09, 2009
  15. Oct 04, 2009
  17. Oct 03, 2009
  19. Oct 01, 2009
  21. Sep 30, 2009
    • Linus Torvalds's avatar
      pty: reconnect the BSD TIOCSPTLCK handling to legacy ptys · 342a5971
      Linus Torvalds authored 
      

David Howells noticed (due to the compiler warning about an unused
'pty_ops_bsd' variable) that we haven't actually been using the code
that implements TIOCSPTLCK for legacy pty handling.  It's been that way
since 2.6.26, commit 3e8e88ca to be
exact ("pty: prepare for tty->ops changes").

DavidH initially submitted a patch just removing the dead code entirely,
and since nobody has apparently ever complained, I'm not entirely sure
that wouldn't be the right thing to do.  But since the whole and only
point of the legacy pty code is to be compatible with legacy distros
that don't use the new unix98 pty model, let's just wire it up again.

And clean it up a bit while we're at it.

Acked-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      342a5971
  23. Sep 27, 2009
    • Dave Young's avatar
      tty: Fix regressions caused by commit b50989dc · f278a2f7
      Dave Young authored 
      The following commit made console open fails while booting:

	commit b50989dc
	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: default avatarDave Young <hidave.darkstar@gmail.com>
[ rjw: Rebased on top of 2.6.31-git, reworked the changelog. ]
Signed-off-by: default avatar"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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f278a2f7
    • Alexey Dobriyan's avatar
      const: mark struct vm_struct_operations · f0f37e2f
      Alexey Dobriyan authored 
      

* mark struct vm_area_struct::vm_ops as const
* mark vm_ops in AGP code

But leave TTM code alone, something is fishy there with global vm_ops
being used.

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f0f37e2f
  25. Sep 24, 2009
  27. Sep 23, 2009
  29. Sep 22, 2009
  31. Sep 21, 2009