tick: Sched: Restructure code

Get rid of one indentation level. Preparatory patch for a major
rework. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203502.101563235@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0f07ff2ba22be5b53dd5311f7e356087c2085e02..4c5f4a9dcc0a5f550146c8269ea4b2f78b8e6e4c 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -611,112 +611,103 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
                }
        }
 
+       if ((long)delta_jiffies <= 1) {
+               if (!ts->tick_stopped)
+                       goto out;
+               if (delta_jiffies == 0) {
+                       /* Tick is stopped, but required now. Enforce it */
+                       tick_nohz_restart(ts, now);
+                       goto out;
+               }
+       }
+
        /*
-        * Do not stop the tick, if we are only one off (or less)
-        * or if the cpu is required for RCU:
+        * If this cpu is the one which updates jiffies, then give up
+        * the assignment and let it be taken by the cpu which runs
+        * the tick timer next, which might be this cpu as well. If we
+        * don't drop this here the jiffies might be stale and
+        * do_timer() never invoked. Keep track of the fact that it
+        * was the one which had the do_timer() duty last. If this cpu
+        * is the one which had the do_timer() duty last, we limit the
+        * sleep time to the timekeeping max_deferement value which we
+        * retrieved above. Otherwise we can sleep as long as we want.
         */
-       if (!ts->tick_stopped && delta_jiffies <= 1)
-               goto out;
-
-       /* Schedule the tick, if we are at least one jiffie off */
-       if ((long)delta_jiffies >= 1) {
-
-               /*
-                * If this cpu is the one which updates jiffies, then
-                * give up the assignment and let it be taken by the
-                * cpu which runs the tick timer next, which might be
-                * this cpu as well. If we don't drop this here the
-                * jiffies might be stale and do_timer() never
-                * invoked. Keep track of the fact that it was the one
-                * which had the do_timer() duty last. If this cpu is
-                * the one which had the do_timer() duty last, we
-                * limit the sleep time to the timekeeping
-                * max_deferement value which we retrieved
-                * above. Otherwise we can sleep as long as we want.
-                */
-               if (cpu == tick_do_timer_cpu) {
-                       tick_do_timer_cpu = TICK_DO_TIMER_NONE;
-                       ts->do_timer_last = 1;
-               } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
-                       time_delta = KTIME_MAX;
-                       ts->do_timer_last = 0;
-               } else if (!ts->do_timer_last) {
-                       time_delta = KTIME_MAX;
-               }
+       if (cpu == tick_do_timer_cpu) {
+               tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+               ts->do_timer_last = 1;
+       } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
+               time_delta = KTIME_MAX;
+               ts->do_timer_last = 0;
+       } else if (!ts->do_timer_last) {
+               time_delta = KTIME_MAX;
+       }
 
 #ifdef CONFIG_NO_HZ_FULL
-               if (!ts->inidle) {
-                       time_delta = min(time_delta,
-                                        scheduler_tick_max_deferment());
-               }
+       if (!ts->inidle)
+               time_delta = min(time_delta, scheduler_tick_max_deferment());
 #endif
 
+       /*
+        * calculate the expiry time for the next timer wheel
+        * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that
+        * there is no timer pending or at least extremely far into
+        * the future (12 days for HZ=1000). In this case we set the
+        * expiry to the end of time.
+        */
+       if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
                /*
-                * calculate the expiry time for the next timer wheel
-                * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
-                * that there is no timer pending or at least extremely
-                * far into the future (12 days for HZ=1000). In this
-                * case we set the expiry to the end of time.
+                * Calculate the time delta for the next timer event.
+                * If the time delta exceeds the maximum time delta
+                * permitted by the current clocksource then adjust
+                * the time delta accordingly to ensure the
+                * clocksource does not wrap.
                 */
-               if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
-                       /*
-                        * Calculate the time delta for the next timer event.
-                        * If the time delta exceeds the maximum time delta
-                        * permitted by the current clocksource then adjust
-                        * the time delta accordingly to ensure the
-                        * clocksource does not wrap.
-                        */
-                       time_delta = min_t(u64, time_delta,
-                                          tick_period.tv64 * delta_jiffies);
-               }
-
-               if (time_delta < KTIME_MAX)
-                       expires = ktime_add_ns(last_update, time_delta);
-               else
-                       expires.tv64 = KTIME_MAX;
+               time_delta = min_t(u64, time_delta,
+                                  tick_period.tv64 * delta_jiffies);
+       }
 
-               /* Skip reprogram of event if its not changed */
-               if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
-                       goto out;
+       if (time_delta < KTIME_MAX)
+               expires = ktime_add_ns(last_update, time_delta);
+       else
+               expires.tv64 = KTIME_MAX;
 
-               ret = expires;
+       /* Skip reprogram of event if its not changed */
+       if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
+               goto out;
 
-               /*
-                * nohz_stop_sched_tick can be called several times before
-                * the nohz_restart_sched_tick is called. This happens when
-                * interrupts arrive which do not cause a reschedule. In the
-                * first call we save the current tick time, so we can restart
-                * the scheduler tick in nohz_restart_sched_tick.
-                */
-               if (!ts->tick_stopped) {
-                       nohz_balance_enter_idle(cpu);
-                       calc_load_enter_idle();
+       ret = expires;
 
-                       ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
-                       ts->tick_stopped = 1;
-                       trace_tick_stop(1, " ");
-               }
+       /*
+        * nohz_stop_sched_tick can be called several times before
+        * the nohz_restart_sched_tick is called. This happens when
+        * interrupts arrive which do not cause a reschedule. In the
+        * first call we save the current tick time, so we can restart
+        * the scheduler tick in nohz_restart_sched_tick.
+        */
+       if (!ts->tick_stopped) {
+               nohz_balance_enter_idle(cpu);
+               calc_load_enter_idle();
 
-               /*
-                * If the expiration time == KTIME_MAX, then
-                * in this case we simply stop the tick timer.
-                */
-                if (unlikely(expires.tv64 == KTIME_MAX)) {
-                       if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
-                               hrtimer_cancel(&ts->sched_timer);
-                       goto out;
-                }
+               ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
+               ts->tick_stopped = 1;
+               trace_tick_stop(1, " ");
+       }
 
-                if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
-                        hrtimer_start(&ts->sched_timer, expires,
-                                      HRTIMER_MODE_ABS_PINNED);
-                else
-                        tick_program_event(expires, 1);
-       } else {
-               /* Tick is stopped, but required now. Enforce it */
-               tick_nohz_restart(ts, now);
+       /*
+        * If the expiration time == KTIME_MAX, then
+        * in this case we simply stop the tick timer.
+        */
+       if (unlikely(expires.tv64 == KTIME_MAX)) {
+               if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
+                       hrtimer_cancel(&ts->sched_timer);
+               goto out;
        }
 
+       if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
+               hrtimer_start(&ts->sched_timer, expires,
+                             HRTIMER_MODE_ABS_PINNED);
+       else
+               tick_program_event(expires, 1);
 out:
        ts->next_jiffies = next_jiffies;
        ts->last_jiffies = last_jiffies;