On Fri, 2012-08-17 at 20:15 +0200, Jiri Slaby wrote:
> On 08/17/2012 07:39 PM, Joe Perches wrote:
> > On Fri, 2012-08-17 at 15:42 +0200, Jiri Slaby wrote:
> >> Before calling __ratelimit in __WARN_RATELIMIT, check the condition
> >> first. When this check was not there, we got constant income of:
> >> tty_init_dev: 60 callbacks suppressed
> >> tty_init_dev: 59 callbacks suppressed
> > []
> >> diff --git a/include/linux/ratelimit.h b/include/linux/ratelimit.h
> > []
> >> @@ -49,8 +49,9 @@ extern int ___ratelimit(struct ratelimit_state *rs,
> >> const char *func);
> >> #define __WARN_RATELIMIT(condition, state, format...) \
> >> ({ \
> >> int rtn = 0; \
> >> - if (unlikely(__ratelimit(state))) \
> >> - rtn = WARN(condition, format); \
> >> + int __rtcond = !!condition; \
> >> + if (unlikely(__rtcond && __ratelimit(state))) \
> >> + rtn = WARN(__rtcond, format); \
> >> rtn; \
> >> })
> >>
> >
> > Hi Jiri.
> >
> > This seems fine to me but are there any conditions that
> > are computationally expensive?
>
> It's not about expensiveness of the computation. The complexity remained
> the same except I moved the computation one layer up.
If ratelimit(state) is not true, condition wasn't tested
or performed at all. With this change, it's always done.
> > Maybe something like this?
[]
> Yup, something like that looks OK to me.
OK, David, do you want an official patch?
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