linux-kernel - Re: [PATCH 14/15] kernel: convert futex_pi_state.refcount from atomic_t to refcount

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Date:   Mon, 17 Jul 2017 16:25:36 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Elena Reshetova <elena.reshetova@...el.com>
cc:     linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
        linux-audit@...hat.com, linux-fsdevel@...r.kernel.org,
        peterz@...radead.org, gregkh@...uxfoundation.org,
        viro@...iv.linux.org.uk, tj@...nel.org, mingo@...hat.com,
        hannes@...xchg.org, lizefan@...wei.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, eparis@...hat.com,
        akpm@...ux-foundation.org, arnd@...db.de, luto@...nel.org,
        keescook@...omium.org
Subject: Re: [PATCH 14/15] kernel: convert futex_pi_state.refcount from
 atomic_t to refcount_t

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'.

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.

> 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.

Other than that, the patch itself is fine.

Thanks,

	tglx