Commit 896b969e authored by Yunfeng Ye's avatar Yunfeng Ye Committed by Thomas Gleixner
Browse files

tick/sched: Release seqcount before invoking calc_load_global() 



calc_load_global() does not need the sequence count protection.

[ tglx: Split it up properly and added comments ]

Signed-off-by: default avatarYunfeng Ye <yeyunfeng@huawei.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201117132006.660902274@linutronix.de
parent 7a35bf2a

kernel/time/tick-sched.c

+11 −1
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/sched/clock.h>

#include <linux/sched/stat.h>

#include <linux/sched/nohz.h>

#include <linux/sched/loadavg.h>

#include <linux/module.h>

#include <linux/irq_work.h>

#include <linux/posix-timers.h>
@@ -107,7 +108,8 @@ static void tick_do_update_jiffies64(ktime_t now) 
						tick_period);

	}



	do_timer(ticks);

	/* Advance jiffies to complete the jiffies_seq protected job */

	jiffies_64 += ticks;



	/*

	 * Keep the tick_next_period variable up to date.  WRITE_ONCE()
@@ -116,7 +118,15 @@ static void tick_do_update_jiffies64(ktime_t now) 
	WRITE_ONCE(tick_next_period,

		   ktime_add(last_jiffies_update, tick_period));



	/*

	 * Release the sequence count. calc_global_load() below is not

	 * protected by it, but jiffies_lock needs to be held to prevent

	 * concurrent invocations.

	 */

	write_seqcount_end(&jiffies_seq);



	calc_global_load();



	raw_spin_unlock(&jiffies_lock);

	update_wall_time();

}