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Commit 93dcf55f authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
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wait_task_inactive: "improve" the returned value for ->nvcsw == 0 



wait_task_inactive() returns 1 when p->nvcsw == 0 || p->nvcsw == 1.  This
means that two subsequent calls can return the same number while the task
was scheduled in between.

Change the code to return "nvcsw | LONG_MIN" instead of "nvcsw ?: 1", now
the overlap always needs LONG_MAX schedules.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent f31e11d8

kernel/sched.c

+1 −1
Original line number Diff line number Diff line
@@ -1922,7 +1922,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state) 
		on_rq = p->se.on_rq;

		ncsw = 0;

		if (!match_state || p->state == match_state)

			ncsw = p->nvcsw ?: 1;

			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */

		task_rq_unlock(rq, &flags);



		/*