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    SubjectRe: [PATCH v3 2/2] locking/percpu-rwsem: Annotate rwsem ownership transfer by setting RWSEM_OWNER_UNKNOWN
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    On 05/15/2018 02:05 PM, Peter Zijlstra wrote:
    > On Tue, May 15, 2018 at 02:02:00PM -0400, Waiman Long wrote:
    >> On 05/15/2018 01:58 PM, Peter Zijlstra wrote:
    >>> On Tue, May 15, 2018 at 01:38:04PM -0400, Waiman Long wrote:
    >>>> +/*
    >>>> + * Owner value to indicate the rwsem's owner is not currently known.
    >>>> + */
    >>>> +#define RWSEM_OWNER_UNKNOWN ((struct task_struct *)-1)
    >>> It might be nice to comment that this works and relies on having that
    >>> ANON_OWNER bit set.
    >> I am just trying not to expose internal working of rwsem, but I can
    >> document that one of the bits is the real deal without specifying which one.
    > Thing is, you don't want someone changing this without knowing about
    > that one magic bit. It doesn't hurt to be explicit here.
    >
    > Also, do we want -1L instead of a -1 literal?
    >
    Yes, I should -1L instead.

    Cheers,
    Longman

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