Re: 2.6.28-rc6: hpet: object is on stack, but not annotated

[Alexander Beregalov]

2009/1/12 Ingo Molnar <mingo@xxxxxxx>:
>
> * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
>> > > (No, introducing WARN_ON()s is not fine; it spams kerneloops.org at
>> > > least...)
>> >
>> > The warning is still here on 2.6.29-rc1. It taints the kernel.
>>
>> Does this fix it?
Yes, it does. Thanks Peter.
>
> i've applied it to tip/timers/urgent and will send it to Linus if it
> passes Alexander's testing too. Below is the prettified commit.
Yes, please.
>
> Thanks guys,
>
>        Ingo
> -------------->
> From b1f1006971b6f8d330c6e8ecf240f51c9eb67f4d Mon Sep 17 00:00:00 2001
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Date: Mon, 12 Jan 2009 12:52:23 +0100
> Subject: [PATCH] locking, hpet: annotate false positive warning
>
> Alexander Beregalov reported that this warning is caused by the HPET code:
>
>> hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0
>> hpet0: 3 comparators, 64-bit 14.318180 MHz counter
>> ODEBUG: object is on stack, but not annotated
>> ------------[ cut here ]------------
>> WARNING: at lib/debugobjects.c:251 __debug_object_init+0x2a4/0x352()
>
>> Bisected down to 26afe5f2fbf06ea0765aaa316640c4dd472310c0
>> (x86: HPET_MSI Initialise per-cpu HPET timers)
>
> The commit is fine - but the on-stack workqueue entry needs annotation.
>
> Reported-and-bisected-by: Alexander Beregalov <a.beregalov@xxxxxxxxx>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> ---
>  arch/x86/kernel/hpet.c    |    2 +-
>  include/linux/workqueue.h |    6 ++++++
>  2 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
> index cd759ad..bb2e0f0 100644
> --- a/arch/x86/kernel/hpet.c
> +++ b/arch/x86/kernel/hpet.c
> @@ -628,7 +628,7 @@ static int hpet_cpuhp_notify(struct notifier_block *n,
>
>        switch (action & 0xf) {
>        case CPU_ONLINE:
> -               INIT_DELAYED_WORK(&work.work, hpet_work);
> +               INIT_DELAYED_WORK_ON_STACK(&work.work, hpet_work);
>                init_completion(&work.complete);
>                /* FIXME: add schedule_work_on() */
>                schedule_delayed_work_on(cpu, &work.work, 0);
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index b362911..47151c8 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -118,6 +118,12 @@ struct execute_work {
>                init_timer(&(_work)->timer);                    \
>        } while (0)
>
> +#define INIT_DELAYED_WORK_ON_STACK(_work, _func)               \
> +       do {                                                    \
> +               INIT_WORK(&(_work)->work, (_func));             \
> +               init_timer_on_stack(&(_work)->timer);           \
> +       } while (0)
> +
>  #define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)                     \
>        do {                                                    \
>                INIT_WORK(&(_work)->work, (_func));             \
>
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