Messages in this thread | | | From | Andrei Vagin <> | Date | Sat, 11 Apr 2020 00:33:56 -0700 | Subject | Re: [PATCH v2 0/6] arm64: add the time namespace support |
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On Thu, Apr 9, 2020 at 6:23 AM Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > Hi Andrei, > > On 2/25/20 7:37 AM, Andrei Vagin wrote: > > Allocate the time namespace page among VVAR pages and add the logic > > to handle faults on VVAR properly. > > > > If a task belongs to a time namespace then the VVAR page which contains > > the system wide VDSO data is replaced with a namespace specific page > > which has the same layout as the VVAR page. That page has vdso_data->seq > > set to 1 to enforce the slow path and vdso_data->clock_mode set to > > VCLOCK_TIMENS to enforce the time namespace handling path. > > > > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent > > update of the VDSO data is in progress, is not really affecting regular > > tasks which are not part of a time namespace as the task is spin waiting > > for the update to finish and vdso_data->seq to become even again. > > > > If a time namespace task hits that code path, it invokes the corresponding > > time getter function which retrieves the real VVAR page, reads host time > > and then adds the offset for the requested clock which is stored in the > > special VVAR page. > > > > v2: Code cleanups suggested by Vincenzo. > > > > Sorry for the delay, I completed this morning the review of your patches and I > do not have anymore comments on them. Thank you for making the effort and > bringing the time namespace support to arm64.
Thank you for the review of these patches.
> > I have though a question on something I encountered during the testing of the > patches: I noticed that all the tests related to CLOCK_BOOTTIME_ALARM fail on > arm64 (please find the results below the scissors). Is this expected?
static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp) { struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
if (!alarmtimer_get_rtcdev()) return -EINVAL;
It is probably that you get EINVAL from here ^^^. I will send a separate patch to handle this case in tests properly.
Thanks, Andrei
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