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    SubjectRe: [PATCH] clocksource, prevent overflow in clocksource_cyc2ns


    On 04/19/2012 08:52 AM, Thomas Gleixner wrote:
    > On Thu, 19 Apr 2012, Thomas Gleixner wrote:
    >
    >> On Wed, 18 Apr 2012, John Stultz wrote:
    >>> On 04/18/2012 04:59 PM, Prarit Bhargava wrote:
    >>>>

    >> No. The show_state() part prints into the buffer. But it's not
    >> guaranteed that the buffer is flushed right away. It could be flushed
    >> later as well in a different context. And of course the flush code
    >> runs with interrupts disabled and dumping out a gazillion of lines
    >> over serial will cause the same hickup. Just planting random
    >> touch_watchdog() calls into the code is not the right approach,
    >> really.
    >>
    >> We should think about the reasons why we have interrupts disabled for
    >> so much time. Is that really, really necessary ?

    In the case of the sysrq-t, I would argue that it is. The whole point behind
    the sysrq-t is that we're capturing the *current* state of the system. Having
    that output effected by interrupts seems like a bad idea.

    >
    > I'm not against making the clocksource code more robust, but I don't
    > want to add crap there just to cope with complete madness elsewhere.

    Maybe I came off the wrong way but I completely agree with that sentiment. Like
    yourself, I'm looking for a correct fix rather than a fast fix.

    Sorry that I haven't provided any debug info but I'm still in the gathering data
    stage atm. It was just John's ping that made me "brain dump" the current info I
    had.

    P.


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