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SubjectRe: apm emulation driver broken ?
Rafael J. Wysocki wrote:
> On Saturday, 17 of November 2007, Franck Bui-Huu wrote:
>> Rafael J. Wysocki wrote:
>>> However, using PF_NOFREEZE to prevent this from happening doesn't seem to be
>>> a good idea.
>>>
>> Indeed but...
>>
>>> I'd probably use wait_event_freezable() (defined in
>>> include/linux/freezer.h) for that.
>> ...I would just revert this bits from now to make sure this driver
>> work again for v2.6.24.
>
> I'd prefer not to.
>
> The PF_NOFREEZE was not present in 2.6.23 already and I wouldn't like to
> reintroduce it now.
>
> Why do you think that using wait_event_freezable() would not work, BTW?
>

I've never claimed this. I just said it may be safer to revert the
changes for v2.6.24 and improve the current code for next releases.

>>> It tries to send them fake signals and waits for them to freeze. If
>>> they don't freeze within the timeout, it fails and clears their
>>> TIF_FREEZE bits.
>> But send_fake_signal() seems to wake up task in INTERRUPTIBLE state
>> only. Looking at signal_wake_up(), it basically do:
>>
>> wake_up_state(t, TASK_INTERRUPTIBLE);
>>
>> What am I missing ?
>
> Nothing. :-)
>
> I didn't remember the change that made the freezer use TASK_INTERRUPTIBLE
> explicitly in there (should have looked at the current code before replying).
>

ok so now we agreed on this point, can we assert that a user
land thread waiting for an event in an UNINTERRUPTIBLE state
will prevent a suspend to happen ?

Franck
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