Messages in this thread | | | Date | Sun, 28 Aug 2016 09:57:31 +0800 | From | Chen Yu <> | Subject | Re: [PATCH][RFC v4] timekeeping: ignore the bogus sleep time if pm_trace is enabled |
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On Sat, Aug 27, 2016 at 03:08:56PM +0800, Xunlei Pang wrote: > On 2016/08/18 at 18:43, Chen Yu wrote: > > Previously we encountered some memory overflow issues due to > > the bogus sleep time brought by inconsistent rtc, which is > > triggered when pm_trace is enabled, please refer to: > > https://patchwork.kernel.org/patch/9286365/ > > It's improper in the first place to call __timekeeping_inject_sleeptime() > > in case that pm_trace is enabled simply because that "hash" time value > > will wreckage the timekeeping subsystem. > > > > So this patch ignores the sleep time if pm_trace is enabled in > > the following situation: > > 1. rtc is used as persist clock to compensate for sleep time, > > (because system does not have a nonstop clocksource) or > > 2. rtc is used to calculate the sleep time in rtc_resume. > > > > Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > > Cc: John Stultz <john.stultz@linaro.org> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Xunlei Pang <xlpang@redhat.com> > > Cc: Zhang Rui <rui.zhang@intel.com> > > Cc: linux-kernel@vger.kernel.org > > Cc: linux-pm@vger.kernel.org > > Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Reported-by: Janek Kozicki <cosurgi@gmail.com> > > Signed-off-by: Chen Yu <yu.c.chen@intel.com> > > --- > > I suddenly think of a way to avoid adding this ugly __weak auxiliary function. > > Add a special treatment for read_persistent_clock() in arch/x86/kernel/rtc.c as follows, > void read_persistent_clock(struct timespec *ts) > { > x86_platform.get_wallclock(ts); > > /* Make rtc-based persistent clock unusable if pm_trace is enabled. */ > if (pm_trace_is_enabled() && > x86_platform.get_wallclock == mach_get_cmos_time) { > ts->tv_sec = 0; > ts->tv_nsec = 0; > } > } > > In this way, we can avoid the touch of timekeeping core, after all ptrace is currently x86-specific. > > What do you think? > Good point! Will send another version based on this idea.
Thanks, Yu
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