On Wednesday, July 22, 2015 01:15:01 AM Rafael J. Wysocki wrote: > Hi VIresh, > > On Mon, Jul 20, 2015 at 11:47 AM, Viresh Kumar <viresh.ku...@linaro.org> > wrote: > > Consider a dual core (0/1) system with two CPUs: > > - sharing clock/voltage rails and hence cpufreq-policy > > - CPU1 is offline while the cpufreq driver is registered > > > > - cpufreq_add_dev() is called from subsys callback for CPU0 and we > > create the policy for the CPUs and create link for CPU1. > > - cpufreq_add_dev() is called from subsys callback for CPU1, we find > > that the cpu is offline and we try to create a sysfs link for CPU1. > > So the problem is that the cpu_is_offline(cpu) check in > cpufreq_add_dev() matches two distinct cases: (1) the CPU was not > present before and it is just being hot-added and (2) the CPU is > initially offline, but present, and this is the first time its device > is registered. In the first case we can expect that the CPU will > become online shortly (although that is not guaranteed too), but in > the second case that very well may not happen. > > We need to be able to distinguish between those two cases and your > patch does that, but I'm not sure if this really is the most > straightforward way to do it.
It looks like we need a mask of related CPUs that are present. Or, alternatively, a mask of CPUs that would have been related had they been present. That's sort of what your patch is adding, but not quite. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
