tick/nohz: Call tick_nohz_task_switch() with interrupts disabled

mainline inclusion
from mainline-5.14-rc1
commit 0fdcccfa
category: feature
feature: Deep isolation
bugzilla: https://gitee.com/openeuler/kernel/issues/I4N00D
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0fdcccfafcffac70b452b3127cc3d981f0117655

--------------------------------

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: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210512232924.150322-10-frederic@kernel.orgSigned-off-by: NYunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: Nliu chao <liuchao173@huawei.com>
Reviewed-by: NChen Hui <judy.chenhui@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/sched/core.c

@@ -3652,6 +3652,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
 	vtime_task_switch(prev);
 	perf_event_task_sched_in(prev, current);
 	finish_task(prev);
+	tick_nohz_task_switch();
 	finish_lock_switch(rq);
 	finish_arch_post_lock_switch();
 	kcov_finish_switch(current);
@@ -3689,7 +3690,6 @@ static struct rq *finish_task_switch(struct task_struct *prev)
 		put_task_struct_rcu_user(prev);
 	}
 
-	tick_nohz_task_switch();
 	return rq;
 }
 

kernel/time/tick-sched.c

@@ -467,13 +467,10 @@ 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);
 
@@ -482,8 +479,6 @@ 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. */