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    SubjectRe: [RFC][PATCH] ps command race fix take 4 [1/4] callback subroutine
    On Mon, 04 Sep 2006 16:48:43 -0600
    ebiederm@xmission.com (Eric W. Biederman) wrote:

    > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> writes:
    >
    > > Updated some dirty codes. maybe easier to read than previous one.
    > >
    > > This ps command fix (proc_pid_readdir() fix) fixes the problem by
    > >
    > > - attach a callback for updating pointer from file descriptor to a task invoked
    > > at release_task()
    > > - no additional global lock is required.
    > > - walk through all and only task structs which is thread group leader.
    > >
    > > *Bad* point is adding additonal (small) lock and callback in exit path.
    > With an unbounded callback chain length influenced by user space.
    >
    yes. 1000 ps process will add 1000 chains. 1000 callbacks are called if a task is
    removed while 1000 ps task points to it.


    -Kame

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