On Friday, December 06, 2013 10:53:16 AM Srivatsa S. Bhat wrote: > 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. Yeah, and I'd like that to be done. > 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. That's been a workaround to be honest. > So I agree that a fundamental restructuring is in order, to cure all the > innumerable problems. Yes. Thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
