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    Revert "futex_requeue_pi optimization" · bd197234
    Thomas Gleixner authored
    This reverts commit d0aa7a70.
    
    It not only introduced user space visible changes to the futex syscall,
    it is also non-functional and there is no way to fix it proper before
    the 2.6.22 release.
    
    The breakage report ( http://lkml.org/lkml/2007/5/12/17
    
     ) went
    unanswered, and unfortunately it turned out that the concept is not
    feasible at all.  It violates the rtmutex semantics badly by introducing
    a virtual owner, which hacks around the coupling of the user-space
    pi_futex and the kernel internal rt_mutex representation.
    
    At the moment the only safe option is to remove it fully as it contains
    user-space visible changes to broken kernel code, which we do not want
    to expose in the 2.6.22 release.
    
    The patch reverts the original patch mostly 1:1, but contains a couple
    of trivial manual cleanups which were necessary due to patches, which
    touched the same area of code later.
    
    Verified against the glibc tests and my own PI futex tests.
    
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Acked-by: default avatarIngo Molnar <mingo@elte.hu>
    Acked-by: default avatarUlrich Drepper <drepper@redhat.com>
    Cc: Pierre Peiffer <pierre.peiffer@bull.net>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    bd197234