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    SubjectRe: [PATCH v7 1/4] spinlock: A new lockref structure for lockless update of refcount
    On 08/30/2013 04:54 PM, Al Viro wrote:
    > On Fri, Aug 30, 2013 at 01:43:11PM -0700, Linus Torvalds wrote:
    >> On Fri, Aug 30, 2013 at 1:15 PM, Waiman Long<waiman.long@hp.com> wrote:
    >>> The prepend_path() isn't all due to getcwd. The correct profile should be
    >> Ugh. I really think that prepend_path() should just be rewritten to
    >> run entirely under RCU.
    >>
    >> Then we can remove *all* the stupid locking, and replace it with doing
    >> a read-lock on the rename sequence count, and repeating if requited.
    >>
    >> That shouldn't even be hard to do, it just requires mindless massaging
    >> and being careful.
    > Not really. Sure, you'll retry it if you race with d_move(); that's not
    > the real problem - access past the end of the object containing ->d_name.name
    > would screw you and that's what ->d_lock is preventing there. Delayed freeing
    > of what ->d_name is pointing into is fine, but it's not the only way to get
    > hurt there...

    Actually, prepend_path() was called with rename_lock taken. So d_move()
    couldn't be run at the same time. Am I right?

    Regards,
    Longman


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