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SubjectRe: apm emulation driver broken ?
Rafael J. Wysocki wrote:
> On Sunday, 18 of November 2007, Franck Bui-Huu wrote:
>> Rafael J. Wysocki wrote:
>> See the call to wait_even() made by apm_ioctl(). If any processes
>> run this, it will prevent the system to suspend...
>
> True, but does it actually happen in practice?
>

when several processes are waiting for a suspend event.

>
> At this point the second branch of the "if (as->suspend_state == SUSPEND_READ)"
> can be fixed by replacing wait_event_interruptible() with
> wait_event_freezable(),

yes

> but the fix for the first branch depends on whether or
> not the wait_event() is really necessary.

As I said I don't know. It's probably time to put some people
on CC but don't know who though.

>
> If it can be replaced with an interruptible sleep, we can use
> wait_event_freezable() in this case too. Otherwise, the only woking fix would
> be to reintroduce the PF_NOFREEZE in there.

BTW, why not raising PF_NOFREEZE in wait_event(), so thread sleeping
in UNINTERRUPTIBLE state won't prevent suspend to happen ?


Franck
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