RE: [PATCH 14/15] kernel: convert futex_pi_state.refcount from atomic_t to refcount_t

Reshetova, Elena
2017-07-17T16:51:22Z

> On Mon, 17 Jul 2017, Elena Reshetova wrote:
>
> > Subject: kernel: convert futex_pi_state.refcount from atomic_t to refcount_t
>
> Several people including myself told you already, that subjects consist of
>
> SUBSYSTEMPREFIX: Concise description
>
> It's easy enough to figure the prefix out by looking at the output of 'git
> log path/of/changed/file'.

Ok, I will try this from now on. I didn't think of it, but was trying to figure it
based on general location and meaning (obviously wrong).

>
> Concise descriptions are not lengthy sentences with implementation
> details. They should merily describe the problem/concept of change. The
> details go into the changelog. IOW, something like:
>
> "PROPERPREFIX: Convert to refcount API"
>
> would be sufficient.

OK, will fix.

>
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
>
> Copying the same sentence over and over avoids thinking about a proper
> changelog, right? You fail to explain, how you come to the conclusion that
> futex_pi_state.refcount is a pure reference counter (aside of the name) and
> therefor can be safely converted to refcount_t.

OK, this is not very useful for many cases. Yes, I am using automated log on
these patches, because I used to have 240 of them and writing manual logs for them
would be fun. Moreover, in many cases, writing manual logs don't bring any value since
I would have to repeat the same things all over again: xyz conversions was found by using *.cocci
pattern first, then looked at manually and it looked like a standard reference counter that
frees the things after calling refcount_dec_and_test() (or its variation with lock which is rare).
Other things also looked correct, like I didn't see increments from zero, counter starts at 1 etc.
I would really have to repeat the same thing in each changelog. Does it really bring value?

Best Regards,
Elena.
>
> Other than that, the patch itself is fine.
>
> Thanks,
>
> tglx