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SubjectRe: [PATCH -v4 1/2] ratelimit: Extend to print suppressed messages on release
Hi Andrew,

thanks for taking a look.

On Thu, Jul 14, 2016 at 01:29:36PM -0700, Andrew Morton wrote:
> Why? What's driving this? What are the benefits to our users? Are
> there any downsides or back-compatibility issues?
>
> I see from the code that this is not actually enabled by default. The
> client code must use ratelimit_set_flags() to select this behaviour,
> and the second patch uses this. Please include all such info in the
> changelog.

How about:

"This use case is aimed at short-termed, burst-like users of the
ratelimiting facility for which we want to output the suppressed lines
stats only once, after it has been disposed of. For an example, see
usage in /dev/kmsg."

?

> > Separated from a previous patch by Linus.
> >
> > Also, make the ON_RELEASE image not use "callbacks" as it is misleading.
>
> "image"?

Bah, it should say

"Also, change the printk line we issue on release to not use "callbacks"
as it is misleading. We're not suppressing callbacks but printk calls."

> > @@ -46,12 +46,14 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
> > rs->begin = jiffies;
> >
> > if (time_is_before_jiffies(rs->begin + rs->interval)) {
> > - if (rs->missed)
> > - printk(KERN_WARNING "%s: %d callbacks suppressed\n",
> > - func, rs->missed);
> > + if (rs->missed) {
> > + if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
> > + pr_warn("%s: %d callbacks suppressed\n", func, rs->missed);
> > + rs->missed = 0;
> > + }
> > + }
>
> hm, what's the difference between an output line being suppressed and a
> callback being suppressed? I think I've forgotten how this code works ;)

Right, ___ratelimit() gets as @func arg the name of the current calling
function:

#define __ratelimit(state) ___ratelimit(state, __func__)

I'm strongly assuming this is the "callback" ___ratelimit() is talking
about :-)

In our case, we don't have callbacks but /dev/kmsg users and I thought
the most generic way of referring to them would be by not doing so at
all but simply talking about output lines being suppressed.

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
--

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