Messages in this thread | | | Subject | Re: PREEMPT/PREEMPT_RT question | From | Steven Rostedt <> | Date | Tue, 12 Jul 2005 23:54:50 -0400 |
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On Tue, 2005-07-12 at 18:46 -0700, Paul E. McKenney wrote:
> > If you are talking about scheduler_tick, then yes, it is called by the > > timer interrupt which is a SA_NODELAY interrupt. If you don't want to > > get interrupted by the timer interrupt, then you will need to disable > > interrupts for both. Since currently, the timer interrupt is the only > > true hard interrupt in the PREEMPT_RT and that may not change. > > OK, so if I take a spinlock in something invoked from scheduler_tick(), > then any other acquisitions of that spinlock must disable hardware > interrupts, right?
Yes, otherwise you could have a local CPU deadlock on a SMP machine. And I would also say the same is true for any lock that is grabbed by the timer interrupt or one of the functions it calls.
-- Steve
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