tick/nohz: Call tick_nohz_task_switch() with interrupts disabled

Call tick_nohz_task_switch() slightly earlier after the context switch
to benefit from disabled IRQs. This way the function doesn't need to
disable them once more.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210512232924.150322-10-frederic@kernel.org

kernel/time/tick-sched.c

@@ -487,13 +487,10 @@ void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bi
  */
 void __tick_nohz_task_switch(void)
 {
-	unsigned long flags;
 	struct tick_sched *ts;
 
-	local_irq_save(flags);
-
 	if (!tick_nohz_full_cpu(smp_processor_id()))
-		goto out;
+		return;
 
 	ts = this_cpu_ptr(&tick_cpu_sched);
 
@@ -502,8 +499,6 @@ void __tick_nohz_task_switch(void)
 		    atomic_read(&current->signal->tick_dep_mask))
 			tick_nohz_full_kick();
 	}
-out:
-	local_irq_restore(flags);
 }
 
 /* Get the boot-time nohz CPU list from the kernel parameters. */