Re: Fw: [RFC] Strange code in cpu_idle()

From: Zwane Mwaikambo (zwane_at_arm.linux.org.uk)
Date: 12/06/04

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    Date:	Mon, 6 Dec 2004 09:47:04 -0700 (MST)
To: "Paul E. McKenney" <paulmck@us.ibm.com>

    On Mon, 6 Dec 2004, Paul E. McKenney wrote:

    > I am not going to claim to thoroughly understand the power-management
    > code, but do have an additional question.
    >
    > What happens if the processor became aware of a new grace period just
    > before entering pm_idle? I could imagine this code simply refusing
    > to power down the processor if there was a pending grace period, but
    > I don't see any sign of this. I could also imagine somehow deferring
    > interrupts until pm_idle exits. I don't see anything that looks like
    > it does this, but don't claim to be any sort of power-management
    > expert.

    Are you referring to the synchronize_kernel side? That's basically unload
    module path so it's ok if it sits there for a bit, but it should only last
    for as long as the next interrupt, which would be a pretty short perid
    considering HZ=1000. But the usage still has a race and hence invalid as
    pointed out by Dipankar

    Thanks,
            Zwane

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