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

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Date:   Wed, 9 Oct 2019 18:42:27 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        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>,
        Joe Perches <joe@...ches.com>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Aditya Pakki <pakki001@....edu>, Kangjie Lu <kjlu@....edu>,
        Navid Emamdoost <emamd001@....edu>,
        Stephen McCamant <smccaman@....edu>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: string.h: Mark 34 functions with __must_check

> You're also not consistent - strlen() is not annotated.

Would you like to integrate any additional function annotations?


> And, for the standard C functions, -Wall already seems to warn about
> an unused call:

This detail is nice, isn't it?


> a.c:5:2: warning: statement with no effect [-Wunused-value]
>   strlen(s);

Are there any differences to consider for the Linux function variant?


> The problem is the __must_check does not mean that the
> return value must be followed by a comparison to NULL and bailing out
> (that can't really be checked), it simply ensures the return value is
> assigned somewhere or used in an if(). So foo->bar = kstrdup() not
> followed by a check of foo->bar won't warn. So one would essentially
> only catch instant-leaks.

How do you think about to improve the source code analysis support
any further?

Regards,
Markus