futex: remove the pointer math from double_unlock_hb, fix
futex: remove the pointer math from double_unlock_hb, fix

Impact: fix double unlock crash

Thomas Gleixner noticed that the simplified double_unlock_hb()
became ... too unsophisticated: in the hb1 == hb2 case it will
do a double unlock.

Reported-by: Thomas Gleixner <00e4cf8f46a57000a44449bf9dd8cbbcc209fd2a@linutronix.de>
Cc: Darren Hart <6620bce6bfb8b2ba8b188f43804848d35a9a4d76@us.ibm.com>
LKML-Reference: <a4ac78974789ba6e4375879a24cb0531646f4022@Aeon>
Signed-off-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@elte.hu>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas