Re: [announce] "kill the Big Kernel Lock (BKL)" tree - Kernel

This is a discussion on Re: [announce] "kill the Big Kernel Lock (BKL)" tree - Kernel ; Out of amusement I took the watchdog drivers and started looking for large cans of worms in the BKL drop arena. Here is a fun one for general discussion - right now driver probe functions request resources. We have no ...

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Thread: Re: [announce] "kill the Big Kernel Lock (BKL)" tree

  1. Re: [announce] "kill the Big Kernel Lock (BKL)" tree

    Out of amusement I took the watchdog drivers and started looking for
    large cans of worms in the BKL drop arena.

    Here is a fun one for general discussion - right now driver probe
    functions request resources. We have no ordering on the requests so we
    have deadlocks if two drivers do resource requests for conflicting
    resources in reverse order.

    "Discuss"

    Alan
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  2. Re: [announce] "kill the Big Kernel Lock (BKL)" tree



    On Wed, 14 May 2008, Alan Cox wrote:
    >
    > Here is a fun one for general discussion - right now driver probe
    > functions request resources. We have no ordering on the requests so we
    > have deadlocks if two drivers do resource requests for conflicting
    > resources in reverse order.


    resource requests aren't blocking, so it wouldn't actually be a deadlock.
    It would just be a "both failed, try again".

    That said, two drivers shouldn't be probing the same hardware at the same
    time regardless, so I can't imagine that it's much of a problem in real
    life.

    Linus
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  3. Re: [announce] "kill the Big Kernel Lock (BKL)" tree

    Alan Cox writes:

    > Out of amusement I took the watchdog drivers and started looking for
    > large cans of worms in the BKL drop arena.
    >
    > Here is a fun one for general discussion - right now driver probe
    > functions request resources. We have no ordering on the requests so we
    > have deadlocks if two drivers do resource requests for conflicting
    > resources in reverse order.


    What deadlocks? resource allocation normally doesn't block. So if there's
    a ordering issue one of them will fail and should bail out.

    That said if you have conflicting resources then failing is the correct
    behavior anyways.

    -Andi
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