linux-kernel - Re: [PATCH] string.h: Mark 34 functions with __must

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Message-ID: <CAKwvOdntBXd3OPiCV5adcDjXor886-XnsSxcStAjYBJpuEBrqQ@mail.gmail.com>
Date:   Wed, 9 Oct 2019 10:33:45 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Markus Elfring <Markus.Elfring@....de>,
        kernel-janitors@...r.kernel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Subject: Re: [PATCH] string.h: Mark 34 functions with __must_check

On Wed, Oct 9, 2019 at 9:38 AM Joe Perches <joe@...ches.com> wrote:
>
> On Wed, 2019-10-09 at 09:13 -0700, Nick Desaulniers wrote:
> > On Wed, Oct 9, 2019 at 8:09 AM Steven Rostedt <rostedt@...dmis.org> wrote:
> > > On Wed, 9 Oct 2019 14:14:28 +0200 Markus Elfring <Markus.Elfring@....de> wrote:
> []
> > > > Several functions return values with which useful data processing
> > > > should be performed. These values must not be ignored then.
> > > > Thus use the annotation “__must_check” in the shown function declarations.
> []
> > > I'm curious. How many warnings showed up when you applied this patch?
> >
> > I got zero for x86_64 and arm64 defconfig builds of linux-next with
> > this applied.  Hopefully that's not an argument against the more
> > liberal application of it?  I view __must_check as a good thing, and
> > encourage its application, unless someone can show that a certain
> > function would be useful to call without it.
>
> stylistic trivia, neither agreeing nor disagreeing with the patch
> as I generally avoid reading Markus' patches.
>
> I believe __must_check is best placed before the return type as
> that makes grep for function return type easier to parse.
>
> i.e. prefer
>         [static inline] __must_check <type> <function>(<args...>);
> over
>         [static inline] <type> __must_check <function>(<args...>);
>

+ Miguel
So I just checked `__cold`, and `__cold` is all over the board in
style.  I see it:
1. before anything fs/btrfs/super.c#L101
2. after static before return type (what you recommend) fs/btrfs/super.c#L2318
3. after return type fs/btrfs/inode.c#L9426

Can we pick a style and enforce it via checkpatch? (It's probably not
fun to check for each function attribute in
include/linux/compiler_attributes.h).
-- 
Thanks,
~Nick Desaulniers