Re: [RFC PATCH v2 1/5] futex: Add futex_set_timer() helper function

[Waiman Long]

On 09/22/2016 05:31 PM, Thomas Gleixner wrote:
> On Tue, 20 Sep 2016, Waiman Long wrote:
>
> Please be more careful of your subject lines. First thing I thought was
> that you add a helper which is used in later patches to find out that you
> actualy consolidate duplicated code. Something like:
>
>    futex: Consolidate duplicated timer setup code
>
> would have told me right away what this is about.
>
> > This patch adds a new futex_set_timer() function to consolidate all
> Please do not use: "This patch ...". We already know that this is a patch,
> otherwise it would not be tagged [PATCH n/m] in the subject line.
>
> See Documentation/SubmittingPatches ....
>
> > the sleeping hrtime setup code.
> Let me give you a hint:
>
> 1:  The code has three identical code copies to set up the futex timeout.
>
> 2:  Add a helper function and consolidate the call sites.
>
> #1 tells precisely what the problem is
> #2 tells precisely how it is solved
>
> Can you see the difference?
>
> > +/*
> > + * Helper function to set the sleeping hrtimer.
> > + */
> > +static inline void futex_set_timer(ktime_t *time, struct hrtimer_sleeper **pto,
> > +		struct hrtimer_sleeper *timeout, int flags, u64 range_ns)
> Please use futex_setup_timer() as the function name. I was confused when I
> read the other patch that you wanted to "set" the timer before entering
> into the place which would actually need it.
>
> > +{
> > +	if (!time)
> > +		return;
> > +	*pto = timeout;
> Please don't do that. That's a horrible coding style.
>
> What's wrong with returning NULL or the timeout pointer and assign it to
> "to" at the call site?
>
> Thanks,
>
> 	tglx

Thanks for the suggestions. I will fix this patch in the next revision.

Cheers,
Longman