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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: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Oleg Nesterov 2008-08-20 16:54:44 -07:00 committed by Ingo Molnar
parent f31e11d87a
commit 93dcf55f82
1 changed files with 1 additions and 1 deletions
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2
kernel/sched.c
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@ -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);
/*