Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH for 2.5] preemptible kernel | Date | Thu, 05 Apr 2001 03:51:11 +1000 |
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In message <Pine.LNX.4.05.10104011347060.14420-100000@cosmic.nrg.org> you write : > > Setting a running task's flags brings races, AFAICT, and checking > > p->state is NOT sufficient, consider wait_event(): you need p->has_cpu > > here I think. > > My thought here was that if p->state is anything other than TASK_RUNNING > or TASK_RUNNING|TASK_PREEMPTED, then that task is already at a > synchonize point,
Right. Theoretically possible to set p->state and not sleep, but it's not a bad assumption.
> > schedule(): > > if (!(prev->state & TASK_PREEMPTED) && prev->syncing) > > if (--sync_count == 0) wake_up(&syncing_task); > > Don't forget to reset prev->syncing.
Right.
> I agree with you about wait queues, but didn't use them here because > of the problem of avoiding deadlock on the runqueue lock, which the > wait queues also use.
And right again. Yeah, it has to be done manually. Ack, can I retract that Email?
Rusty. -- Premature optmztion is rt of all evl. --DK - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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