commit bb1f30cb7d3ba21098f0ee7e0382160ba2599a43
Author: Oleg Nesterov <oleg@redhat.com>
Date:   Fri Jun 28 09:53:57 2013 +1000

    wait: introduce wait_event_common(wq, condition, state, timeout)
    
    1. 4c663cfc "fix false timeouts when using wait_event_timeout()"
       is not enough, wait(wq, true, 0) still returns zero.
    
       __wait_event_timeout() was already fixed but we need the same
       logic in wait_event_timeout() if the fast-path check succeeds.
    
    2. wait_event_timeout/__wait_event_timeout interface do not match
       wait_event(), you can't use __wait_event_timeout() instead of
       wait_event_timeout() if you do not need the fast-path check.
    
       Same for wait_event_interruptible/__wait_event_interruptible,
       so this patch cleanups rtlx.c, ip_vs_sync.c, and af_irda.c:
    
    	-	__wait_event_interruptible(wq, cond, ret);
    	+	ret = __wait_event_interruptible(wq, cond);
    
    3. wait_event_* macros duplicate the same code.
    
    This patch adds a single helper wait_event_common() which hopefully
    does everything right. Compiler optimizes out the "dead" code when
    we do not need signal_pending/schedule_timeout.
    
    "size vmlinux" reports:
    
    		   text	   data	    bss	    dec	    hex	filename
    	-	4978601	2935080	10104832	18018513	112f0d1	vmlinux
    	+	4977769	2930984	10104832	18013585	112dd91	vmlinux
    
    but I think this depends on gcc/config.
    
    In particular, wait_even_timeout(true, non_const_timeout) should
    generate more code in the non-void context because the patch adds
    the additional code to fix the 1st problem.
    
    Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    Reviewed-by: Tejun Heo <tj@kernel.org>
    Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
    Cc: Imre Deak <imre.deak@intel.com>
    Cc: Lukas Czerner <lczerner@redhat.com>
    Cc: Samuel Ortiz <samuel@sortiz.org>
    Cc: Wensong Zhang <wensong@linux-vs.org>
    Cc: Simon Horman <horms@verge.net.au>
    Cc: Julian Anastasov <ja@ssi.bg>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>