linux-toradex.git/include/linux/wait.h, branch v2.6.36-rc5

Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6

2010-05-21T04:26:12+00:00

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (229 commits)
  USB: remove unused usb_buffer_alloc and usb_buffer_free macros
  usb: musb: update gfp/slab.h includes
  USB: ftdi_sio: fix legacy SIO-device header
  USB: kl5usb105: reimplement using generic framework
  USB: kl5usb105: minor clean ups
  USB: kl5usb105: fix memory leak
  USB: io_ti: use kfifo to implement write buffering
  USB: io_ti: remove unsused private counter
  USB: ti_usb: use kfifo to implement write buffering
  USB: ir-usb: fix incorrect write-buffer length
  USB: aircable: fix incorrect write-buffer length
  USB: safe_serial: straighten out read processing
  USB: safe_serial: reimplement read using generic framework
  USB: safe_serial: reimplement write using generic framework
  usb-storage: always print quirks
  USB: usb-storage: trivial debug improvements
  USB: oti6858: use port write fifo
  USB: oti6858: use kfifo to implement write buffering
  USB: cypress_m8: use kfifo to implement write buffering
  USB: cypress_m8: remove unused drain define
  ...

Fix up conflicts (due to usb_buffer_alloc/free renaming) in
	drivers/input/tablet/acecad.c
	drivers/input/tablet/kbtab.c
	drivers/input/tablet/wacom_sys.c
	drivers/media/video/gspca/gspca.c
	sound/usb/usbaudio.c

wait_event_interruptible_locked() interface

2010-05-20T20:21:42+00:00

New wait_event_interruptible{,_exclusive}_locked{,_irq} macros added.
They work just like versions without _locked* suffix but require the
wait queue's lock to be held.  Also __wake_up_locked() is now exported
as to pair it with the above macros.

The use case of this new facility is when one uses wait queue's lock
to  protect a data structure.  This may be advantageous if the
structure needs to be protected by a spinlock anyway.  In particular,
with additional spinlock the following code has to be used to wait
for a condition:

spin_lock(&data.lock);
...
for (ret = 0; !ret && !(condition); ) {
	spin_unlock(&data.lock);
	ret = wait_event_interruptible(data.wqh, (condition));
	spin_lock(&data.lock);
}
...
spin_unlock(&data.lock);

This looks bizarre plus wait_event_interruptible() locks the wait
queue's lock anyway so there is a unlock+lock sequence where it could
be avoided.

To avoid those problems and benefit from wait queue's lock, a code
similar to the following should be used:

/* Waiting */
spin_lock(&data.wqh.lock);
...
ret = wait_event_interruptible_locked(data.wqh, (condition));
...
spin_unlock(&data.wqh.lock);

/* Waiting exclusively */
spin_lock(&data.whq.lock);
...
ret = wait_event_interruptible_exclusive_locked(data.whq, (condition));
...
spin_unlock(&data.whq.lock);

/* Waking up */
spin_lock(&data.wqh.lock);
...
wake_up_locked(&data.wqh);
...
spin_unlock(&data.wqh.lock);

When spin_lock_irq() is used matching versions of macros need to be
used (*_locked_irq()).

Signed-off-by: Michal Nazarewicz 
Cc: Kyungmin Park 
Cc: Marek Szyprowski 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Takashi Iwai 
Cc: David Howells 
Cc: Andreas Herrmann 
Cc: Thomas Gleixner 
Cc: Mike Galbraith 
Signed-off-by: Greg Kroah-Hartman

sched, wait: Use wrapper functions

2010-05-11T15:43:58+00:00

epoll should not touch flags in wait_queue_t. This patch introduces a new
function __add_wait_queue_exclusive(), for the users, who use wait queue as a
LIFO queue.

__add_wait_queue_tail_exclusive() is introduced too instead of
add_wait_queue_exclusive_locked(). remove_wait_queue_locked() is removed, as
it is a duplicate of __remove_wait_queue(), disliked by users, and with less
users.

Signed-off-by: Changli Gao 
Signed-off-by: Peter Zijlstra 
Cc: Alexander Viro 
Cc: Paul Menage 
Cc: Li Zefan 
Cc: Davide Libenzi 
Cc: 
LKML-Reference: <1273214006-2979-1-git-send-email-xiaosuo@gmail.com>
Signed-off-by: Ingo Molnar

sched: Rename sync arguments

2009-09-15T14:51:30+00:00

In order to extend the functions to have more than 1 flag (sync),
rename the argument to flags, and explicitly define a WF_ space for
individual flags.

Signed-off-by: Peter Zijlstra 
LKML-Reference: 
Signed-off-by: Ingo Molnar

locking, sched: Give waitqueue spinlocks their own lockdep classes

2009-08-10T12:43:09+00:00

Give waitqueue spinlocks their own lockdep classes when they
are initialised from init_waitqueue_head().  This means that
struct wait_queue::func functions can operate other waitqueues.

This is used by CacheFiles to catch the page from a backing fs
being unlocked and to wake up another thread to take a copy of
it.

Signed-off-by: Peter Zijlstra 
Signed-off-by: David Howells 
Tested-by: Takashi Iwai 
Cc: linux-cachefs@redhat.com
Cc: torvalds@osdl.org
Cc: akpm@linux-foundation.org
LKML-Reference: <20090810113305.17284.81508.stgit@warthog.procyon.org.uk>
Signed-off-by: Ingo Molnar

Merge commit 'v2.6.30-rc5' into sched/core

2009-05-11T10:59:37+00:00

Merge reason: sched/core was on .30-rc1 before, update to latest fixes

Signed-off-by: Ingo Molnar

net: Avoid extra wakeups of threads blocked in wait_for_packet()

2009-04-28T09:24:21+00:00

In 2.6.25 we added UDP mem accounting.

This unfortunatly added a penalty when a frame is transmitted, since
we have at TX completion time to call sock_wfree() to perform necessary
memory accounting. This calls sock_def_write_space() and utimately
scheduler if any thread is waiting on the socket.
Thread(s) waiting for an incoming frame was scheduled, then had to sleep
again as event was meaningless.

(All threads waiting on a socket are using same sk_sleep anchor)

This adds lot of extra wakeups and increases latencies, as noted
by Christoph Lameter, and slows down softirq handler.

Reference : http://marc.info/?l=linux-netdev&m=124060437012283&w=2 

Fortunatly, Davide Libenzi recently added concept of keyed wakeups
into kernel, and particularly for sockets (see commit
37e5540b3c9d838eb20f2ca8ea2eb8072271e403 
epoll keyed wakeups: make sockets use keyed wakeups)

Davide goal was to optimize epoll, but this new wakeup infrastructure
can help non epoll users as well, if they care to setup an appropriate
handler.

This patch introduces new DEFINE_WAIT_FUNC() helper and uses it
in wait_for_packet(), so that only relevant event can wakeup a thread
blocked in this function.

Trace of function calls from bnx2 TX completion bnx2_poll_work() is :
__kfree_skb()
 skb_release_head_state()
  sock_wfree()
   sock_def_write_space()
    __wake_up_sync_key()
     __wake_up_common()
      receiver_wake_function() : Stops here since thread is waiting for an INPUT


Reported-by: Christoph Lameter 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

wait: don't use __wake_up_common()

2009-04-14T15:17:16+00:00

'777c6c5 wait: prevent exclusive waiter starvation' made
__wake_up_common() global to be used from abort_exclusive_wait().

It was needed to do a wake-up with the waitqueue lock held while
passing down a key to the wake-up function.

Since '4ede816 epoll keyed wakeups: add __wake_up_locked_key() and
__wake_up_sync_key()' there is an appropriate wrapper for this case:
__wake_up_locked_key().

Use it here and make __wake_up_common() private to the scheduler
again.

Signed-off-by: Johannes Weiner 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
LKML-Reference: <1239720785-19661-1-git-send-email-hannes@cmpxchg.org>
Signed-off-by: Ingo Molnar

epoll keyed wakeups: introduce new *_poll() wakeup macros

2009-04-01T15:59:20+00:00

Introduce new wakeup macros that allow passing an event mask to the wakeup
targets.  They exactly mimic their non-_poll() counterpart, with the added
event mask passing capability.  I did add only the ones currently
requested, avoiding the _nr() and _all() for the moment.

Signed-off-by: Davide Libenzi 
Cc: Alan Cox 
Cc: Ingo Molnar 
Cc: David Miller 
Cc: William Lee Irwin III 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

epoll keyed wakeups: add __wake_up_locked_key() and __wake_up_sync_key()

2009-04-01T15:59:20+00:00

This patchset introduces wakeup hints for some of the most popular (from
epoll POV) devices, so that epoll code can avoid spurious wakeups on its
waiters.

The problem with epoll is that the callback-based wakeups do not, ATM,
carry any information about the events the wakeup is related to.  So the
only choice epoll has (not being able to call f_op->poll() from inside the
callback), is to add the file* to a ready-list and resolve the real events
later on, at epoll_wait() (or its own f_op->poll()) time.  This can cause
spurious wakeups, since the wake_up() itself might be for an event the
caller is not interested into.

The rate of these spurious wakeup can be pretty high in case of many
network sockets being monitored.

By allowing devices to report the events the wakeups refer to (at least
the two major classes - POLLIN/POLLOUT), we are able to spare useless
wakeups by proper handling inside the epoll's poll callback.

Epoll will have in any case to call f_op->poll() on the file* later on,
since the change to be done in order to have the full event set sent via
wakeup, is too invasive for the way our f_op->poll() system works (the
full event set is calculated inside the poll function - there are too many
of them to even start thinking the change - also poll/select would need
change too).

Epoll is changed in a way that both devices which send event hints, and
the ones that don't, are correctly handled.  The former will gain some
efficiency though.

As a general rule for devices, would be to add an event mask by using
key-aware wakeup macros, when making up poll wait queues.  I tested it
(together with the epoll's poll fix patch Andrew has in -mm) and wakeups
for the supported devices are correctly filtered.

Test program available here:

http://www.xmailserver.org/epoll_test.c

This patch:

Nothing revolutionary here.  Just using the available "key" that our
wakeup core already support.  The __wake_up_locked_key() was no brainer,
since both __wake_up_locked() and __wake_up_locked_key() are thin wrappers
around __wake_up_common().

The __wake_up_sync() function had a body, so the choice was between
borrowing the body for __wake_up_sync_key() and calling it from
__wake_up_sync(), or make an inline and calling it from both.  I chose the
former since in most archs it all resolves to "mov $0, REG; jmp ADDR".

Signed-off-by: Davide Libenzi 
Cc: Alan Cox 
Cc: Ingo Molnar 
Cc: David Miller 
Cc: William Lee Irwin III 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds