On Mon, 14 May 2007 12:11:37 -0700 Andrew Morton <[EMAIL PROTECTED]> wrote:
> > This of course raises another question: it is not clear in which context > > the smp_call_function* functions are supposed to be called. Should it be > > with preemption disabled or is preemption enabled allowed as well? > > If calling with preemption enabled is allowed then the powerpc > > implementation > > is broken, since smp_processor_id() as well as num_online_cpus() may change > > while they are accessed. > > These are all excellent questions. And important ones. erk, I see your point. If a caller is calling this with preemption enabled then the current thread might at any time migrate onto the target CPU, causing the smp_call_function_single() attempt to fail. So the effects of that call are basically a random crapshoot. Often but not always, any code which is hanging onto a variable called "cpu" while preemption enabled is buggy. So yes, I'd say that from a sanity-of-implementation POV and for general defensiveness, we should require that the called of smp_call_function_single() has disabled preemption. What a crock. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
