Hi Steven,
Thanks for your reply,
On Wed, 2018-08-01 at 21:48 -0400, Steven Rostedt wrote:
> I'm just catching up from my vacation. What about making rs->missed
> into an atomic, and have:
>
> if (!raw_spin_trylock_irqsave(&rs->lock, flags)) {
> atomic_inc(&rs->missed);
> return 0;
> }
>
> ?
Uhm. Do you mean as a preparation patch to split this on two patches?
Because it will not solve the issue where one CPU has taken rs->lock,
and is updating rs->printed, checking burst and whatnot; while the
second CPU will loose the message which was even *under* burst limit.
I.e.: there are enough of printk_ratelimit() users in tree and a
message from one can be suppressed, while shouldn't.
> You would also need to do:
>
> if (time_is_before_jiffies(rs->begin + rs->interval)) {
> int missed = atomic_xchg(&rs->missed, 0);
> if (missed) {
>
> So that you don't have a race between checking rs->missed and setting
> it
> to zero.
--
Thanks,
Dmitry
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