futex: use current->time_slack_ns for rt tasks too

RT tasks should set their timer slack to 0 on their own.  This
patch removes the 'if (rt_task()) slack = 0;' block in
futex_wait.

Build and boot tested on a 4 way Intel x86_64 workstation.
Passes basic pthread_mutex and PI tests out of
ltp/testcases/realtime.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20090312075559.9856.28822.stgit@Aeon>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/futex.c b/kernel/futex.c
index e149545..6579912 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1253,16 +1253,13 @@ retry:
                if (!abs_time)
                        schedule();
                else {
-                       unsigned long slack;
-                       slack = current->timer_slack_ns;
-                       if (rt_task(current))
-                               slack = 0;
                        hrtimer_init_on_stack(&t.timer,
                                              clockrt ? CLOCK_REALTIME :
                                              CLOCK_MONOTONIC,
                                              HRTIMER_MODE_ABS);
                        hrtimer_init_sleeper(&t, current);
-                       hrtimer_set_expires_range_ns(&t.timer, *abs_time, slack);
+                       hrtimer_set_expires_range_ns(&t.timer, *abs_time,
+                                                    current->timer_slack_ns);
 
                        hrtimer_start_expires(&t.timer, HRTIMER_MODE_ABS);
                        if (!hrtimer_active(&t.timer))