On Tue, 2 Jun 2015, Jiri Bohac wrote:
> > Looking over the leapsecond code, I noticed the printk messages
> > reporting the leapsecond insertion in the second_overflow path
> > were not using the printk_deferred method. This was surprising
> > since the printk_deferred method was added in part to avoid
> > printk-ing while holding the timekeeping locks.
> >
> > See 6d9bcb621b0b (timekeeping: use printk_deferred when holding
> > timekeeping seqlock) for further rational.
> >
> > I can only guess that this omission was a git add -p oversight.
>
> second_overflow() is called from accumulate_nsecs_to_secs().
>
> accumulate_nsecs_to_secs() is called from update_wall_time()
> - once directly
> - once via logarithmic_accumulation()
> Both calls are before write_seqcount_begin(&tk_core.seq).
>
> So it looks safe to use printk there.
Couldn't we stuff a couple of
!lockdep_is_held()
assertions into printk() so that we don't have to keep rediscovering this
sort of problems over and over again?
Thanks,
--
Jiri Kosina
SUSE Labs
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