Messages in this thread | | | Subject | Re: [PATCH] sched_rt: the task in irq context can be migrated during context switching | From | Steven Rostedt <> | Date | Thu, 05 Jan 2012 13:15:42 -0500 |
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On Thu, 2012-01-05 at 18:55 +0100, Peter Zijlstra wrote:
> So the problem is quite real, as already said we don't need to worry > about the future, but we might want to fix this in previous kernels. > What I'm not entirely sure of is the proposed solution, Steven don't we > get in trouble by simply bailing out on the push?
It shouldn't break anything. We shouldn't be pushing tasks that are running on a rq anyway. I don't see any harm here. As this scenario can only happen if we get an interrupt after letting go of the rq lock and before doing the switch_to(). The schedule_tail() calls post_schedule_rt() which does the push again, and will push task A at that time.
That said, I'm not sure this patch is enough. I'm worried about a pull happening. As task A is running, we could possible possibly pick it on another CPU to do a pull.
Hmm, looking at the code, the pull already does a task_running() test, so I guess we should be fine.
Acked-by: Steven Rostedt <rostedt@goodmis.org>
-- Steve
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