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    SubjectRe: Extended f_count patch (SMP-safe handling of struct file)
    	New version of the patch is on

    * bad race in select (both SMP and UP) fixed. Old code does
    fcheck(fd) and might block before incrementing f_count; to trigger
    that one needs a select() on fdset with >170 members. Exploitable
    (clone() with COPY_FILES, select() in one thread, close() in
    another + right timing). Result being the dangling pointer to
    struct file. With all usual consequences.
    * race in dup2() fixed. (dup2(fd1,fd2) in one thread, close(fd1) in
    another, right timing and you've got both fd1 and fd2 closed)
    * bad race in do_load_aout_binary() fixed (more or less the same -
    exec() vs. close() instead of select() vs. close()).
    * fget(), get_unused_fd(), put_unused_fd(), sys_dup(), sys_dup2() -
    SMP-safe. Big lock shifting will follow - there's more to do here.
    * ->files->fd[] handling became SMP-safe (or so I hope ;-). It will
    need more cleanup and quite possibly some fixes, but the main
    part is there. Big mess remains in arch/* - it will be the next
    thing to fix. I didn't include large fd array support, but it
    should be easy to do now.
    * fput() made inline (thanks, Alexey). It still requires the big
    * AF_UNIX handling of in-flight count fixed (ditto).

    So there... I'm not posting the thing to l-k - 66K is over the top.
    Comments are more than welcome, indeed. Patch is against 2.3.9-pre1 and
    it's *dangerous* - it may open new races somewhere. You've been warned.
    It should compile, but that's about all I can say. To be continued...

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