Messages in this thread | | | Date | Tue, 04 Jun 2002 15:24:57 -0700 | From | george anzinger <> | Subject | Re: Race: SignalHandler() & sleep() |
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Hossein Mobahi wrote: > > Hello > > main() > { > .... > signal (SIGIO, signalhandler() ) ; > .... > sleep (65535) ; > .... > } > > signalhandler() { ... } > > Assume the frequency of IO events is faster than one > event per 65535 seconds. Therefore, let's consider > 65535 as infinity (sleeping foreveR). > If a SIGIO arrives, main will get out of sleep and > continue running, but signalhandler will be invoked > too. I wanted to know if there is any order/priority > for sleep() in main, and signalhandler() to be called > first, or one of them is invoked first randomly (race > condition) ? > > I myself ran the program many times and everytime > observed signalhandler responding first. But maybe it > is not a rule, and it was just my chance ? > In linux (and most (all) unices) pending signals are checked for on exit from the kernel so the order of operation is:
wake up (end of sleep) still in kernel on exit from kernel, find signal, and deliver it, i.e. call handler if there is one on return from the handler, continue with the exit from the system.
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Real time sched: http://sourceforge.net/projects/rtsched/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - 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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