Messages in this thread | | | Date | Thu, 28 Apr 2022 18:19:13 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 7/9] ptrace: Simplify the wait_task_inactive call in ptrace_check_attach |
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On 04/28, Peter Zijlstra wrote: > > On Thu, Apr 28, 2022 at 04:57:50PM +0200, Oleg Nesterov wrote: > > > > Shouldn't we then switch wait_task_inactive() so have & matching instead > > > of the current ==. > > > > Sorry, I don't understand the context... > > This.. I've always found it strange to have wti use a different matching > scheme from ttwu.
Ah. This is what I understood (and I too thought about this), just I meant that this patch from Eric (assuming wait_task_inactive() still uses __TASK_TRACED) is fine without your change below.
Oleg.
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index f259621f4c93..c039aef4c8fe 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3304,7 +3304,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state > * is actually now running somewhere else! > */ > while (task_running(rq, p)) { > - if (match_state && unlikely(READ_ONCE(p->__state) != match_state)) > + if (match_state && unlikely(!(READ_ONCE(p->__state) & match_state))) > return 0; > cpu_relax(); > } > @@ -3319,7 +3319,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state > running = task_running(rq, p); > queued = task_on_rq_queued(p); > ncsw = 0; > - if (!match_state || READ_ONCE(p->__state) == match_state) > + if (!match_state || (READ_ONCE(p->__state) & match_state)) > ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ > task_rq_unlock(rq, p, &rf);
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