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

From: Waiman Long
Date: Thu Sep 22 2016 - 20:45:30 EST

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