Eric Lee / smarc-fsl-linux-kernel

03 Feb, 2009

1 commit

20 Jan, 2009

2 commits

  • 8ccad40df   work_on_cpu: Use our own workqueue. ... Browse Code »

    Impact: remove potential clashes with generic kevent workqueue

    Annoyingly, some places we want to use work_on_cpu are already in
    workqueues. As per Ingo's suggestion, we create a different workqueue
    for work_on_cpu.

    Signed-off-by: Rusty Russell
    Signed-off-by: Mike Travis
    Signed-off-by: Ingo Molnar

    Rusty Russell
     
  • 31ad90812   work_on_cpu: don't try to get_online_cpus() in work_on_cpu. ... Browse Code »

    Impact: remove potential circular lock dependency with cpu hotplug lock

    This has caused more problems than it solved, with a pile of cpu
    hotplug locking issues.

    Followup patches will get_online_cpus() in callers that need it, but
    if they don't do it they're no worse than before when they were using
    set_cpus_allowed without locking.

    Signed-off-by: Rusty Russell
    Signed-off-by: Mike Travis
    Signed-off-by: Ingo Molnar

    Rusty Russell
     

14 Jan, 2009

1 commit

  • e1d8aa9f1   tracing: add a new workqueue tracer ... Browse Code »

    Impact: new tracer

    The workqueue tracer provides some statistical informations
    about each cpu workqueue thread such as the number of the
    works inserted and executed since their creation. It can help
    to evaluate the amount of work each of them have to perform.
    For example it can help a developer to decide whether he should
    choose a per cpu workqueue instead of a singlethreaded one.

    It only traces statistical informations for now but it will probably later
    provide event tracing too.

    Such a tracer could help too, and be improved, to help rt priority sorted
    workqueue development.

    To have a snapshot of the workqueues state at any time, just do

    cat /debugfs/tracing/trace_stat/workqueues

    Ie:

    1 125 125 reiserfs/1
    1 0 0 scsi_tgtd/1
    1 0 0 aio/1
    1 0 0 ata/1
    1 114 114 kblockd/1
    1 0 0 kintegrityd/1
    1 2147 2147 events/1

    0 0 0 kpsmoused
    0 105 105 reiserfs/0
    0 0 0 scsi_tgtd/0
    0 0 0 aio/0
    0 0 0 ata_aux
    0 0 0 ata/0
    0 0 0 cqueue
    0 0 0 kacpi_notify
    0 0 0 kacpid
    0 149 149 kblockd/0
    0 0 0 kintegrityd/0
    0 1000 1000 khelper
    0 2270 2270 events/0

    Changes in V2:

    _ Drop the static array based on NR_CPU and dynamically allocate the stat array
    with num_possible_cpus() and other cpu mask facilities....
    _ Trace workqueue insertion at a bit lower level (insert_work instead of queue_work) to handle
    even the workqueue barriers.

    Signed-off-by: Frederic Weisbecker
    Signed-off-by: Steven Rostedt
    Signed-off-by: Ingo Molnar

    Frederic Weisbecker
     

01 Jan, 2009

1 commit

  • e7577c50f   cpumask: convert kernel/workqueue.c ... Browse Code »

    Impact: Reduce memory usage, use new cpumask API.

    cpu_populated_map becomes a cpumask_var_t, and cpu_singlethread_map is
    simply a cpumask pointer: it's simply the cpumask containing the first
    possible CPU anyway.

    Signed-off-by: Rusty Russell

    Rusty Russell
     

14 Nov, 2008

2 commits

06 Nov, 2008

1 commit

  • 2d3854a37   cpumask: introduce new API, without changing anything ... Browse Code »

    Impact: introduce new APIs

    We want to deprecate cpumasks on the stack, as we are headed for
    gynormous numbers of CPUs. Eventually, we want to head towards an
    undefined 'struct cpumask' so they can never be declared on stack.

    1) New cpumask functions which take pointers instead of copies.
    (cpus_* -> cpumask_*)

    2) Several new helpers to reduce requirements for temporary cpumasks
    (cpumask_first_and, cpumask_next_and, cpumask_any_and)

    3) Helpers for declaring cpumasks on or offstack for large NR_CPUS
    (cpumask_var_t, alloc_cpumask_var and free_cpumask_var)

    4) 'struct cpumask' for explicitness and to mark new-style code.

    5) Make iterator functions stop at nr_cpu_ids (a runtime constant),
    not NR_CPUS for time efficiency and for smaller dynamic allocations
    in future.

    6) cpumask_copy() so we can allocate less than a full cpumask eventually
    (for alloc_cpumask_var), and so we can eliminate the 'struct cpumask'
    definition eventually.

    7) work_on_cpu() helper for doing task on a CPU, rather than saving old
    cpumask for current thread and manipulating it.

    8) smp_call_function_many() which is smp_call_function_mask() except
    taking a cpumask pointer.

    Note that this patch simply introduces the new functions and leaves
    the obsolescent ones in place. This is to simplify the transition
    patches.

    Signed-off-by: Rusty Russell
    Signed-off-by: Ingo Molnar

    Rusty Russell
     

22 Oct, 2008

1 commit

  • 0d557dc97   workqueue: introduce create_rt_workqueue ... Browse Code »

    create_rt_workqueue will create a real time prioritized workqueue.
    This is needed for the conversion of stop_machine to a workqueue based
    implementation.
    This patch adds yet another parameter to __create_workqueue_key to tell
    it that we want an rt workqueue.
    However it looks like we rather should have something like "int type"
    instead of singlethread, freezable and rt.

    Signed-off-by: Heiko Carstens
    Signed-off-by: Rusty Russell
    Cc: Ingo Molnar

    Heiko Carstens
     

17 Oct, 2008

1 commit

12 Aug, 2008

1 commit

11 Aug, 2008

2 commits

31 Jul, 2008

1 commit

26 Jul, 2008

8 commits

  • 8448502cf   workqueues: do CPU_UP_CANCELED if CPU_UP_PREPARE fails ... Browse Code »

    The bug was pointed out by Akinobu Mita , and this
    patch is based on his original patch.

    workqueue_cpu_callback(CPU_UP_PREPARE) expects that if it returns
    NOTIFY_BAD, _cpu_up() will send CPU_UP_CANCELED then.

    However, this is not true since

    "cpu hotplug: cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE"
    commit: a0d8cdb652d35af9319a9e0fb7134de2a276c636

    The callback which has returned NOTIFY_BAD will not receive
    CPU_UP_CANCELED. Change the code to fulfil the CPU_UP_CANCELED logic if
    CPU_UP_PREPARE fails.

    Signed-off-by: Oleg Nesterov
    Reported-by: Akinobu Mita
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 8de6d308b   workqueues: schedule_on_each_cpu() can use schedule_work_on() ... Browse Code »

    schedule_on_each_cpu() can use schedule_work_on() to avoid the code
    duplication.

    Signed-off-by: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • ef1ca236b   workqueues: queue_work() can use queue_work_on() ... Browse Code »

    queue_work() can use queue_work_on() to avoid the code duplication.

    Signed-off-by: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • a67da70dc   workqueues: lockdep annotations for flush_work() ... Browse Code »

    Add lockdep annotations to flush_work() and update the comment.

    Signed-off-by: Oleg Nesterov
    Cc: Jarek Poplawski
    Acked-by: Johannes Berg
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 3da1c84c0   workqueues: make get_online_cpus() useable for work->func() ... Browse Code »

    workqueue_cpu_callback(CPU_DEAD) flushes cwq->thread under
    cpu_maps_update_begin(). This means that the multithreaded workqueues
    can't use get_online_cpus() due to the possible deadlock, very bad and
    very old problem.

    Introduce the new state, CPU_POST_DEAD, which is called after
    cpu_hotplug_done() but before cpu_maps_update_done().

    Change workqueue_cpu_callback() to use CPU_POST_DEAD instead of CPU_DEAD.
    This means that create/destroy functions can't rely on get_online_cpus()
    any longer and should take cpu_add_remove_lock instead.

    [akpm@linux-foundation.org: fix CONFIG_SMP=n]
    Signed-off-by: Oleg Nesterov
    Acked-by: Gautham R Shenoy
    Cc: Heiko Carstens
    Cc: Max Krasnyansky
    Cc: Paul Jackson
    Cc: Paul Menage
    Cc: Peter Zijlstra
    Cc: Vegard Nossum
    Cc: Martin Schwidefsky
    Cc: Ingo Molnar
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 8616a89ab   workqueues: schedule_on_each_cpu: use flush_work() ... Browse Code »

    Change schedule_on_each_cpu() to use flush_work() instead of
    flush_workqueue(), this way we don't wait for other work_struct's which
    can be queued meanwhile.

    Signed-off-by: Oleg Nesterov
    Cc: Jarek Poplawski
    Cc: Max Krasnyansky
    Cc: Peter Zijlstra
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • db7008972   workqueues: implement flush_work() ... Browse Code »

    Most of users of flush_workqueue() can be changed to use cancel_work_sync(),
    but sometimes we really need to wait for the completion and cancelling is not
    an option. schedule_on_each_cpu() is good example.

    Add the new helper, flush_work(work), which waits for the completion of the
    specific work_struct. More precisely, it "flushes" the result of of the last
    queue_work() which is visible to the caller.

    For example, this code

    queue_work(wq, work);
    /* WINDOW */
    queue_work(wq, work);

    flush_work(work);

    doesn't necessary work "as expected". What can happen in the WINDOW above is

    - wq starts the execution of work->func()

    - the caller migrates to another CPU

    now, after the 2nd queue_work() this work is active on the previous CPU, and
    at the same time it is queued on another. In this case flush_work(work) may
    return before the first work->func() completes.

    It is trivial to add another helper

    int flush_work_sync(struct work_struct *work)
    {
    return flush_work(work) || wait_on_work(work);
    }

    which works "more correctly", but it has to iterate over all CPUs and thus
    it much slower than flush_work().

    Signed-off-by: Oleg Nesterov
    Acked-by: Max Krasnyansky
    Acked-by: Jarek Poplawski
    Cc: Peter Zijlstra
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 1a4d9b0aa   workqueues: insert_work: use "list_head *" instead of "int tail" ... Browse Code »

    insert_work() inserts the new work_struct before or after cwq->worklist,
    depending on the "int tail" parameter. Change it to accept "list_head *"
    instead, this shrinks .text a bit and allows us to insert the barrier
    after specific work_struct.

    Signed-off-by: Oleg Nesterov
    Cc: Jarek Poplawski
    Cc: Max Krasnyansky
    Cc: Peter Zijlstra
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     

25 Jul, 2008

1 commit

  • c1a220e7a   pm: introduce new interfaces schedule_work_on() and queue_work_on() ... Browse Code »

    This interface allows adding a job on a specific cpu.

    Although a work struct on a cpu will be scheduled to other cpu if the cpu
    dies, there is a recursion if a work task tries to offline the cpu it's
    running on. we need to schedule the task to a specific cpu in this case.
    http://bugzilla.kernel.org/show_bug.cgi?id=10897

    [oleg@tv-sign.ru: cleanups]
    Signed-off-by: Zhang Rui
    Tested-by: Rus
    Signed-off-by: Rafael J. Wysocki
    Acked-by: Pavel Machek
    Signed-off-by: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Zhang Rui
     

06 Jul, 2008

1 commit

05 Jul, 2008

1 commit

  • cde535359   Christoph has moved ... Browse Code »

    Remove all clameter@sgi.com addresses from the kernel tree since they will
    become invalid on June 27th. Change my maintainer email address for the
    slab allocators to cl@linux-foundation.org (which will be the new email
    address for the future).

    Signed-off-by: Christoph Lameter
    Signed-off-by: Christoph Lameter
    Cc: Pekka Enberg
    Cc: Stephen Rothwell
    Cc: Matt Mackall
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Christoph Lameter
     

24 May, 2008

1 commit

01 May, 2008

1 commit

  • 8a3e77cc2   workqueue: remove redundant function invocation ... Browse Code »

    timer_stats_timer_set_start_info is invoked twice, additionally, the
    invocation of this function can be moved to where it is only called when a
    delay is really required.

    Signed-off-by: Andrew Liu
    Cc: Pavel Machek
    Cc: Ingo Molnar
    Cc: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrew Liu
     

30 Apr, 2008

1 commit

29 Apr, 2008

2 commits

  • 1e35eaa2d   cleanup_workqueue_thread: remove the unneeded "cpu" parameter ... Browse Code »

    cleanup_workqueue_thread() doesn't need the second argument, remove it.

    Signed-off-by: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 00dfcaf74   workqueues: shrink cpu_populated_map when CPU dies ... Browse Code »

    When cpu_populated_map was introduced, it was supposed that cwq->thread can
    survive after CPU_DEAD, that is why we never shrink cpu_populated_map.

    This is not very nice, we can safely remove the already dead CPU from the map.
    The only required change is that destroy_workqueue() must hold the hotplug
    lock until it destroys all cwq->thread's, to protect the cpu_populated_map.
    We could make the local copy of cpu mask and drop the lock, but
    sizeof(cpumask_t) may be very large.

    Also, fix the comment near queue_work(). Unless _cpu_down() happens we do
    guarantee the cpu-affinity of the work_struct, and we have users which rely on
    this.

    [akpm@linux-foundation.org: repair comment]
    Signed-off-by: Oleg Nesterov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     

17 Apr, 2008

1 commit

09 Feb, 2008

2 commits

26 Jan, 2008

1 commit

16 Jan, 2008

1 commit

  • eb13ba873   lockdep: fix workqueue creation API lockdep interaction ... Browse Code »

    Dave Young reported warnings from lockdep that the workqueue API
    can sometimes try to register lockdep classes with the same key
    but different names. This is not permitted in lockdep.

    Unfortunately, I was unaware of that restriction when I wrote
    the code to debug workqueue problems with lockdep and used the
    workqueue name as the lockdep class name. This can obviously
    lead to the problem if the workqueue name is dynamic.

    This patch solves the problem by always using a constant name
    for the workqueue's lockdep class, namely either the constant
    name that was passed in or a string consisting of the variable
    name.

    Signed-off-by: Johannes Berg
    Signed-off-by: Ingo Molnar
    Signed-off-by: Peter Zijlstra

    Johannes Berg
     

20 Oct, 2007

2 commits

  • ba25f9dcc   Use helpers to obtain task pid in printks ... Browse Code »

    The task_struct->pid member is going to be deprecated, so start
    using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in
    the kernel.

    The first thing to start with is the pid, printed to dmesg - in
    this case we may safely use task_pid_nr(). Besides, printks produce
    more (much more) than a half of all the explicit pid usage.

    [akpm@linux-foundation.org: git-drm went and changed lots of stuff]
    Signed-off-by: Pavel Emelyanov
    Cc: Dave Airlie
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Pavel Emelyanov
     
  • 4e6045f13   workqueue: debug flushing deadlocks with lockdep ... Browse Code »

    In the following scenario:

    code path 1:
    my_function() -> lock(L1); ...; flush_workqueue(); ...

    code path 2:
    run_workqueue() -> my_work() -> ...; lock(L1); ...

    you can get a deadlock when my_work() is queued or running
    but my_function() has acquired L1 already.

    This patch adds a pseudo-lock to each workqueue to make lockdep
    warn about this scenario.

    [akpm@linux-foundation.org: coding-style fixes]
    Signed-off-by: Johannes Berg
    Acked-by: Oleg Nesterov
    Acked-by: Ingo Molnar
    Acked-by: Peter Zijlstra
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Johannes Berg
     

28 Aug, 2007

1 commit

  • d243769d3   fix bogus hotplug cpu warning ... Browse Code »

    Fix bogus DEBUG_PREEMPT warning on x86_64, when cpu brought online after
    bootup: current_is_keventd is right to note its use of smp_processor_id
    is preempt-safe, but should use raw_smp_processor_id to avoid the warning.

    Signed-off-by: Hugh Dickins
    Signed-off-by: Linus Torvalds

    Hugh Dickins
     

18 Jul, 2007

2 commits

  • 13c22168b   destroy_workqueue() can livelock ... Browse Code »

    Pointed out by Michal Schmidt .

    The bug was introduced in 2.6.22 by me.

    cleanup_workqueue_thread() does flush_cpu_workqueue(cwq) in a loop until
    ->worklist becomes empty. This is live-lockable, a re-niced caller can get
    CPU after wake_up() and insert a new barrier before the lower-priority
    cwq->thread has a chance to clear ->current_work.

    Change cleanup_workqueue_thread() to do flush_cpu_workqueue(cwq) only once.
    We can rely on the fact that run_workqueue() won't return until it flushes
    all works. So it is safe to call kthread_stop() after that, the "should
    stop" request won't be noticed until run_workqueue() returns.

    Signed-off-by: Oleg Nesterov
    Cc: Michal Schmidt
    Cc: Srivatsa Vaddagiri
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Oleg Nesterov
     
  • 831441862   Freezer: make kernel threads nonfreezable by default ... Browse Code »

    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
    Acked-by: Nigel Cunningham
    Cc: Pavel Machek
    Cc: Oleg Nesterov
    Cc: Gautham R Shenoy
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Rafael J. Wysocki