On 12/06/2013 03:59 AM, Rafael J. Wysocki wrote: > On Thursday, December 05, 2013 06:11:19 PM Srivatsa S. Bhat wrote: >> On 12/05/2013 12:27 PM, Bjørn Mork wrote: >>> Viresh Kumar <viresh.kumar@xxxxxxxxxx> writes: >>> >>>> Sending from phone.. html.. so left list. >>>> >>>> Here is the old thread where we discussed this.. see if this helps.. >>>> >>>> http://marc.info/?t=136845016900003&r=1&w=2 >>> >>> Thanks. That helped a lot. >>> >>> Unless I miss something, it looks like the permission problem *started* >>> with fallout from special suspend code - surprising the user by not >>> creating any offline/online event on suspend/resume. Quoting from >>> http://marc.info/?l=linux-pm&m=136847781510358 : >>> >>> (And yes, even code-wise, we use a slightly different >>> path in the S3 code, to initiate hotplug. That's why the uevents >>> are by-passed.) >>> >> >> I hope you didn't miss the main idea I was trying to convey in that >> reply: >> "IMHO, using CPU hotplug (offline/online of CPUs) in the S3 path is >> supposed to be totally internal to the suspend/resume code. It is not >> intended for userspace to know that we are internally offlining/ >> onlining CPUs." > > By the way, in the meantime I discussed this with Viresh in the context of > a different (although related) fix and I suggested a different approach. > > Namely, to split the CPU offline/online code into "core" and "add-ons" > parts, where the core part will do just whatever is needed to offline/online > CPU cores cleanly and the "add-ons" part will carry out the rest (e.g. > removal/addition of sysfs attributes and so on). > > Then, the system suspend/resume code path will only run the "core" part > and whatever else CPU handling is needed during suspend/resume will be > carried out by the device suspend/resume code (via driver callbacks or > stuff similar to cpufreq_suspend() and cpufreq_resume() recently proposed > by Viresh). > > In turn, the "runtime" CPU offline/online will carry out both the core > and the add-ons parts as it does today. > > In my view this should address the problems we have with sysfs attributes, > governors start/stop etc. during system suspend/resume. > Hmm, yes that sounds like a good idea. Are you suggesting this "core" and "add-on" split only for the cpufreq parts of CPU hotplug or for everything involved in CPU hotplug code? IIUC you are suggesting the latter, which is likely to be a significant undertaking, but very well worth it in the long run, since it gives us an elegant solution for all these problems. I guess the *_FROZEN CPU hotplug notifications were originally introduced to provide us an infrastructure to do something like this, but obviously that hasn't worked out very well. So I agree that a fundamental restructuring is in order, to cure all the innumerable problems. Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
