Merge branch 'timers/core-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core

Pull dynticks updates from Frederic Weisbecker:

  * Fix a bug where posix cpu timers requeued due to interval got ignored on full
    dynticks CPUs (not a regression though as it only impacts full dynticks and the
    bug is there since we merged full dynticks).

  * Optimizations and cleanups on the use of per CPU APIs to improve code readability,
    performance and debuggability in the nohz subsystem;

  * Optimize posix cpu timer by sparing stub workqueue queue with full dynticks off case

  * Rename some functions to extend with *_this_cpu() suffix for clarity

  * Refine the naming of some context tracking subsystem state accessors

  * Trivial spelling fix by Paul Gortmaker

Signed-off-by: Ingo Molnar <mingo@kernel.org>

6 files changed, 35 insertions, 47 deletions

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index e5f3917aa05b..6cb20d2e7ee0 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -53,10 +53,10 @@ void context_tracking_user_enter(void)
         /*
          * Repeat the user_enter() check here because some archs may be calling
          * this from asm and if no CPU needs context tracking, they shouldn't
-         * go further. Repeat the check here until they support the static key
-         * check.
+         * go further. Repeat the check here until they support the inline static
+         * key check.
          */
-        if (!static_key_false(&context_tracking_enabled))
+        if (!context_tracking_is_enabled())
                 return;
 
         /*
@@ -160,7 +160,7 @@ void context_tracking_user_exit(void)
 {
         unsigned long flags;
 
-        if (!static_key_false(&context_tracking_enabled))
+        if (!context_tracking_is_enabled())
                 return;
 
         if (in_interrupt())
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index c7f31aa272f7..79747b7d9420 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -608,7 +608,8 @@ static DECLARE_WORK(nohz_kick_work, nohz_kick_work_fn);
  */
 static void posix_cpu_timer_kick_nohz(void)
 {
-        schedule_work(&nohz_kick_work);
+        if (context_tracking_is_enabled())
+                schedule_work(&nohz_kick_work);
 }
 
 bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
@@ -1090,7 +1091,8 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
                         put_task_struct(p);
                         timer->it.cpu.task = p = NULL;
                         timer->it.cpu.expires = 0;
-                        goto out_unlock;
+                        read_unlock(&tasklist_lock);
+                        goto out;
                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
                         /*
                          * We've noticed that the thread is dead, but
@@ -1099,7 +1101,8 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
                          */
                         cpu_timer_sample_group(timer->it_clock, p, &now);
                         clear_dead_task(timer, now);
-                        goto out_unlock;
+                        read_unlock(&tasklist_lock);
+                        goto out;
                 }
                 spin_lock(&p->sighand->siglock);
                 cpu_timer_sample_group(timer->it_clock, p, &now);
@@ -1113,10 +1116,11 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
         BUG_ON(!irqs_disabled());
         arm_timer(timer);
         spin_unlock(&p->sighand->siglock);
-
-out_unlock:
         read_unlock(&tasklist_lock);
 
+        /* Kick full dynticks CPUs in case they need to tick on the new timer */
+        posix_cpu_timer_kick_nohz();
+
 out:
         timer->it_overrun_last = timer->it_overrun;
         timer->it_overrun = -1;
@@ -1256,13 +1260,6 @@ void run_posix_cpu_timers(struct task_struct *tsk)
                         cpu_timer_fire(timer);
                 spin_unlock(&timer->it_lock);
         }
-
-        /*
-         * In case some timers were rescheduled after the queue got emptied,
-         * wake up full dynticks CPUs.
-         */
-        if (tsk->signal->cputimer.running)
-                posix_cpu_timer_kick_nohz();
 }
 
 /*
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 11025ccc06dd..11348de09400 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -311,8 +311,6 @@ asmlinkage void do_softirq(void)
  */
 void irq_enter(void)
 {
-        int cpu = smp_processor_id();
-
         rcu_irq_enter();
         if (is_idle_task(current) && !in_interrupt()) {
                 /*
@@ -320,7 +318,7 @@ void irq_enter(void)
                  * here, as softirq will be serviced on return from interrupt.
                  */
                 local_bh_disable();
-                tick_check_idle(cpu);
+                tick_check_idle();
                 _local_bh_enable();
         }
 
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 9532690daaa9..43780ab5e279 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -538,10 +538,10 @@ int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
  * Called from irq_enter() when idle was interrupted to reenable the
  * per cpu device.
  */
-void tick_check_oneshot_broadcast(int cpu)
+void tick_check_oneshot_broadcast_this_cpu(void)
 {
-        if (cpumask_test_cpu(cpu, tick_broadcast_oneshot_mask)) {
-                struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
+        if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
+                struct tick_device *td = &__get_cpu_var(tick_cpu_device);
 
                 /*
                  * We might be in the middle of switching over from
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 18e71f7fbc2a..e2bced59b6dd 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -51,7 +51,7 @@ extern void tick_broadcast_switch_to_oneshot(void);
 extern void tick_shutdown_broadcast_oneshot(unsigned int *cpup);
 extern int tick_resume_broadcast_oneshot(struct clock_event_device *bc);
 extern int tick_broadcast_oneshot_active(void);
-extern void tick_check_oneshot_broadcast(int cpu);
+extern void tick_check_oneshot_broadcast_this_cpu(void);
 bool tick_broadcast_oneshot_available(void);
 # else /* BROADCAST */
 static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
@@ -62,7 +62,7 @@ static inline void tick_broadcast_oneshot_control(unsigned long reason) { }
 static inline void tick_broadcast_switch_to_oneshot(void) { }
 static inline void tick_shutdown_broadcast_oneshot(unsigned int *cpup) { }
 static inline int tick_broadcast_oneshot_active(void) { return 0; }
-static inline void tick_check_oneshot_broadcast(int cpu) { }
+static inline void tick_check_oneshot_broadcast_this_cpu(void) { }
 static inline bool tick_broadcast_oneshot_available(void) { return true; }
 # endif /* !BROADCAST */
 
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 3612fc77f834..2afd43fca93b 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -391,11 +391,9 @@ __setup("nohz=", setup_tick_nohz);
  */
 static void tick_nohz_update_jiffies(ktime_t now)
 {
-        int cpu = smp_processor_id();
-        struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
         unsigned long flags;
 
-        ts->idle_waketime = now;
+        __this_cpu_write(tick_cpu_sched.idle_waketime, now);
 
         local_irq_save(flags);
         tick_do_update_jiffies64(now);
@@ -426,17 +424,15 @@ update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_upda
 
 }
 
-static void tick_nohz_stop_idle(int cpu, ktime_t now)
+static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now)
 {
-        struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
-
-        update_ts_time_stats(cpu, ts, now, NULL);
+        update_ts_time_stats(smp_processor_id(), ts, now, NULL);
         ts->idle_active = 0;
 
         sched_clock_idle_wakeup_event(0);
 }
 
-static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts)
+static ktime_t tick_nohz_start_idle(struct tick_sched *ts)
 {
         ktime_t now = ktime_get();
 
@@ -752,7 +748,7 @@ static void __tick_nohz_idle_enter(struct tick_sched *ts)
         ktime_t now, expires;
         int cpu = smp_processor_id();
 
-        now = tick_nohz_start_idle(cpu, ts);
+        now = tick_nohz_start_idle(ts);
 
         if (can_stop_idle_tick(cpu, ts)) {
                 int was_stopped = ts->tick_stopped;
@@ -914,8 +910,7 @@ static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
  */
 void tick_nohz_idle_exit(void)
 {
-        int cpu = smp_processor_id();
-        struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+        struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
         ktime_t now;
 
         local_irq_disable();
@@ -928,7 +923,7 @@ void tick_nohz_idle_exit(void)
                 now = ktime_get();
 
         if (ts->idle_active)
-                tick_nohz_stop_idle(cpu, now);
+                tick_nohz_stop_idle(ts, now);
 
         if (ts->tick_stopped) {
                 tick_nohz_restart_sched_tick(ts, now);
@@ -1012,12 +1007,10 @@ static void tick_nohz_switch_to_nohz(void)
  * timer and do not touch the other magic bits which need to be done
  * when idle is left.
  */
-static void tick_nohz_kick_tick(int cpu, ktime_t now)
+static void tick_nohz_kick_tick(struct tick_sched *ts, ktime_t now)
 {
 #if 0
         /* Switch back to 2.6.27 behaviour */
-
-        struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
         ktime_t delta;
 
         /*
@@ -1032,36 +1025,36 @@ static void tick_nohz_kick_tick(int cpu, ktime_t now)
 #endif
 }
 
-static inline void tick_check_nohz(int cpu)
+static inline void tick_check_nohz_this_cpu(void)
 {
-        struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+        struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
         ktime_t now;
 
         if (!ts->idle_active && !ts->tick_stopped)
                 return;
         now = ktime_get();
         if (ts->idle_active)
-                tick_nohz_stop_idle(cpu, now);
+                tick_nohz_stop_idle(ts, now);
         if (ts->tick_stopped) {
                 tick_nohz_update_jiffies(now);
-                tick_nohz_kick_tick(cpu, now);
+                tick_nohz_kick_tick(ts, now);
         }
 }
 
 #else
 
 static inline void tick_nohz_switch_to_nohz(void) { }
-static inline void tick_check_nohz(int cpu) { }
+static inline void tick_check_nohz_this_cpu(void) { }
 
 #endif /* CONFIG_NO_HZ_COMMON */
 
 /*
  * Called from irq_enter to notify about the possible interruption of idle()
  */
-void tick_check_idle(int cpu)
+void tick_check_idle(void)
 {
-        tick_check_oneshot_broadcast(cpu);
-        tick_check_nohz(cpu);
+        tick_check_oneshot_broadcast_this_cpu();
+        tick_check_nohz_this_cpu();
 }
 
 /*