21 Dec, 2011
1 commit
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-> #2 (&tty->write_wait){-.-...}:
is a lot more informative than:
-> #2 (key#19){-.....}:
Signed-off-by: Peter Zijlstra
Cc: Andrew Morton
Cc: Linus Torvalds
Link: http://lkml.kernel.org/n/tip-8zpopbny51023rdb0qq67eye@git.kernel.org
Signed-off-by: Ingo Molnar
06 Oct, 2010
1 commit
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The "flags" member of "struct wait_queue_t" is used in several places in
the kernel code without beeing initialized by init_wait(). "flags" is
used in bitwise operations.If "flags" not initialized then unexpected behaviour may take place.
Incorrect flags might used later in code.Added initialization of "wait_queue_t.flags" with zero value into
"init_wait".Signed-off-by: Evgeny Kuznetsov
[ The bit we care about does end up being initialized by both
prepare_to_wait() and add_to_wait_queue(), so this doesn't seem to
cause actual bugs, but is definitely the right thing to do -Linus ]
Signed-off-by: Linus Torvalds
21 May, 2010
2 commits
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* 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 -
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
11 May, 2010
1 commit
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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:
Signed-off-by: Ingo Molnar
15 Sep, 2009
1 commit
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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
10 Aug, 2009
1 commit
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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:
Signed-off-by: Ingo Molnar
11 May, 2009
1 commit
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Merge reason: sched/core was on .30-rc1 before, update to latest fixes
Signed-off-by: Ingo Molnar
28 Apr, 2009
1 commit
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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 INPUTReported-by: Christoph Lameter
Signed-off-by: Eric Dumazet
Signed-off-by: David S. Miller
14 Apr, 2009
1 commit
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'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:
Signed-off-by: Ingo Molnar
01 Apr, 2009
2 commits
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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 -
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
06 Feb, 2009
1 commit
-
With exclusive waiters, every process woken up through the wait queue must
ensure that the next waiter down the line is woken when it has finished.Interruptible waiters don't do that when aborting due to a signal. And if
an aborting waiter is concurrently woken up through the waitqueue, noone
will ever wake up the next waiter.This has been observed with __wait_on_bit_lock() used by
lock_page_killable(): the first contender on the queue was aborting when
the actual lock holder woke it up concurrently. The aborted contender
didn't acquire the lock and therefor never did an unlock followed by
waking up the next waiter.Add abort_exclusive_wait() which removes the process' wait descriptor from
the waitqueue, iff still queued, or wakes up the next waiter otherwise.
It does so under the waitqueue lock. Racing with a wake up means the
aborting process is either already woken (removed from the queue) and will
wake up the next waiter, or it will remove itself from the queue and the
concurrent wake up will apply to the next waiter after it.Use abort_exclusive_wait() in __wait_event_interruptible_exclusive() and
__wait_on_bit_lock() when they were interrupted by other means than a wake
up through the queue.[akpm@linux-foundation.org: coding-style fixes]
Reported-by: Chris Mason
Signed-off-by: Johannes Weiner
Mentored-by: Oleg Nesterov
Cc: Peter Zijlstra
Cc: Matthew Wilcox
Cc: Chuck Lever
Cc: Nick Piggin
Cc: Ingo Molnar
Cc: ["after some testing"]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Oct, 2008
1 commit
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is_sync_wait() is used to distinguish between sync and async waits.
Basically sync waits are the ones initialized with init_waitqueue_entry()
and async ones with init_waitqueue_func_entry(). The sync/async
distinction is used only in prepare_to_wait[_exclusive]() and its only
function is to skip setting the current task state if the wait is async.
This has a few problems.* No one uses it. None of func_entry users use prepare_to_wait()
functions, so the code path never gets executed.* The distinction is bogus. Maybe back when func_entry is used only
by aio but it's now also used by epoll and in future possibly by 9p
and poll/select.* Taking @state as argument and ignoring it silenly depending on how
@wait is initialized is just a bad error-prone API.* It prevents func_entry waits from using wait->private for no good
reason.This patch kills is_sync_wait() and the associated code paths from
prepare_to_wait[_exclusive](). As there was no user of these code paths,
this patch doesn't cause any behavior difference.Signed-off-by: Tejun Heo
Acked-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Feb, 2008
1 commit
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FASTCALL() is always expanded to empty, remove it.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Feb, 2008
1 commit
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On Sat, 2008-01-05 at 13:35 -0800, Davide Libenzi wrote:
> I remember I talked with Arjan about this time ago. Basically, since 1)
> you can drop an epoll fd inside another epoll fd 2) callback-based wakeups
> are used, you can see a wake_up() from inside another wake_up(), but they
> will never refer to the same lock instance.
> Think about:
>
> dfd = socket(...);
> efd1 = epoll_create();
> efd2 = epoll_create();
> epoll_ctl(efd1, EPOLL_CTL_ADD, dfd, ...);
> epoll_ctl(efd2, EPOLL_CTL_ADD, efd1, ...);
>
> When a packet arrives to the device underneath "dfd", the net code will
> issue a wake_up() on its poll wake list. Epoll (efd1) has installed a
> callback wakeup entry on that queue, and the wake_up() performed by the
> "dfd" net code will end up in ep_poll_callback(). At this point epoll
> (efd1) notices that it may have some event ready, so it needs to wake up
> the waiters on its poll wait list (efd2). So it calls ep_poll_safewake()
> that ends up in another wake_up(), after having checked about the
> recursion constraints. That are, no more than EP_MAX_POLLWAKE_NESTS, to
> avoid stack blasting. Never hit the same queue, to avoid loops like:
>
> epoll_ctl(efd2, EPOLL_CTL_ADD, efd1, ...);
> epoll_ctl(efd3, EPOLL_CTL_ADD, efd2, ...);
> epoll_ctl(efd4, EPOLL_CTL_ADD, efd3, ...);
> epoll_ctl(efd1, EPOLL_CTL_ADD, efd4, ...);
>
> The code "if (tncur->wq == wq || ..." prevents re-entering the same
> queue/lock.Since the epoll code is very careful to not nest same instance locks
allow the recursion.Signed-off-by: Peter Zijlstra
Tested-by: Stefan Richter
Acked-by: Davide Libenzi
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
07 Dec, 2007
2 commits
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Signed-off-by: Matthew Wilcox
-
Also move wake_up_locked() to be with the related functions
Signed-off-by: Matthew Wilcox
10 Jul, 2007
1 commit
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clean up the sleep_on() APIs:
- do not use fastcall
- replace fragile macro magic with proper inline functionsSigned-off-by: Ingo Molnar
31 Oct, 2006
1 commit
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kernel: INFO: trying to register non-static key.
kernel: the code is fine but needs lockdep annotation.
kernel: turning off the locking correctness validator.
kernel: [] show_trace_log_lvl+0x58/0x16a
kernel: [] show_trace+0xd/0x10
kernel: [] dump_stack+0x19/0x1b
kernel: [] __lock_acquire+0xf0/0x90d
kernel: [] lock_acquire+0x4b/0x6b
kernel: [] _spin_lock_irqsave+0x22/0x32
kernel: [] prepare_to_wait+0x17/0x4b
kernel: [] lpfc_do_work+0xdd/0xcc2 [lpfc]
kernel: [] kthread+0xc3/0xf2
kernel: [] kernel_thread_helper+0x5/0xbAnother case of non-static lockdep keys; duplicate the paradigm set by
DECLARE_COMPLETION_ONSTACK and introduce DECLARE_WAIT_QUEUE_HEAD_ONSTACK.Signed-off-by: Peter Zijlstra
Cc: Greg KH
Cc: Markus Lidel
Acked-by: Ingo Molnar
Cc: Arjan van de Ven
Cc: James Bottomley
Cc: Marcel Holtmann
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Jul, 2006
1 commit
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allyesconfig vmlinux size delta:
text data bss dec filename
20736884 6073834 3075176 29885894 vmlinux.before
20721009 6073966 3075176 29870151 vmlinux.after~18 bytes per callsite, 15K of text size (~0.1%) saved.
(as an added bonus this also removes a lockdep annotation.)
Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Jul, 2006
2 commits
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Create one lock class for all waitqueue locks in the kernel. Has no effect on
non-lockdep kernels.Signed-off-by: Ingo Molnar
Signed-off-by: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Locking init improvement:
- introduce and use __SPIN_LOCK_UNLOCKED for array initializations,
to pass in the name string of locks, used by debuggingSigned-off-by: Ingo Molnar
Signed-off-by: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Apr, 2006
1 commit
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Signed-off-by: David Woodhouse
07 Nov, 2005
1 commit
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Fix more include file problems that surfaced since I submitted the previous
fix-missing-includes.patch. This should now allow not to include sched.h
from module.h, which is done by a followup patch.Signed-off-by: Tim Schmielau
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
24 Jun, 2005
1 commit
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In the upcoming aio_down patch, it is useful to store a private data
pointer in the kiocb's wait_queue. Since we provide our own wake up
function and do not require the task_struct pointer, it makes sense to
convert the task pointer into a generic private pointer.Signed-off-by: Benjamin LaHaise
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 May, 2005
1 commit
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Use LIST_HEAD_INIT rather than doing it by hand in DEFINE_WAIT.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso
Signed-off-by: Linus Torvalds
17 Apr, 2005
1 commit
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.Let it rip!
