On 01/06/2016 02:04 PM, John Stultz wrote:
> On Wed, Jan 6, 2016 at 9:34 AM, Thomas Gleixner <t...@linutronix.de> wrote:
>> On Wed, 6 Jan 2016, John Stultz wrote:
>>> On Wed, Jan 6, 2016 at 5:00 AM, Prarit Bhargava <pra...@redhat.com> wrote:
>>>> -ktime_t ktime_get_with_offset(enum tk_offsets offs)
>>>> +ktime_t ktime_get_with_offset(enum tk_offsets offs, int trylock)
>>>> {
>>>> struct timekeeper *tk = &tk_core.timekeeper;
>>>> unsigned int seq;
>>>> ktime_t base, *offset = offsets[offs];
>>>> s64 nsecs;
>>>> + unsigned long flags = 0;
>>>> +
>>>> + if (unlikely(!timekeeping_initialized))
>>>> + return ktime_set(0, 0);
>>>>
>>>> WARN_ON(timekeeping_suspended);
>>>>
>>>> + if (trylock && !raw_spin_trylock_irqsave(&timekeeper_lock, flags))
>>>> + return ktime_set(KTIME_MAX, 0);
>>>
>>> Wait.. this doesn't make sense. The timekeeper lock is only for reading.
>>>
>>> What I was suggesting to you off line is to have something that avoids
>>> spinning on the seqcounter should if a bug occurs and we IPI all the
>>> cpus, that we don't deadlock or block any printk messages.
>>
>> We could also extend the fast timekeeper with boot/real/tai extensions and
>> use
>> that for printk. You can use ktime_get_mono_fast_ns() today.
>
> Ack. There'd be a chance for odd values around when the time is set,
> but for debug printks I think its not critical.
I'll convert to this in v2.
Thanks for the input everyone!
P.
>
> thanks
> -john
>
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