Re: is printk() safe within a timekeeper_seq write section?

From: Jiri Bohac
Date: Wed Mar 12 2014 - 05:21:35 EST


On Tue, Mar 11, 2014 at 02:54:13PM -0700, John Stultz wrote:
> Ok, so a generic solution is probably not going to be worth it then. My
> thought was that since we do a very limited amount of informational
> printks in the timekeeping code, we can be fairly safe delaying the
> print-out until we drop the locks.
>
> For timekeeping, its really 4 call sites:
> * invalid inject_sleep_time deltas
> * > 11% clocksource freq adjustments
> * insert leap second
> * delete leap second

I believe these last two were made safe by
commit ca4523cd (timekeeping: Shorten seq_count region).

write_seqcount_begin(&timekeeper_seq) is now done after the
accumulate_nsecs_to_secs(tk) from where the printks are called.

Regards,

--
Jiri Bohac <jbohac@xxxxxxx>
SUSE Labs, SUSE CZ

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