wait: introduce wait_event_common(wq, condition, state, timeout)

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>