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>

1 files changed, 9 insertions, 12 deletions

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();
 }
 
 /*