linux-kernel - Re: [PATCH v4 4/9] vsprintf: Consolidate handling of unknown pointer specifiers

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Message-ID: <20180407003301.GB386@tigerII.localdomain>
Date:   Sat, 7 Apr 2018 09:33:01 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Petr Mladek <pmladek@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Tobin C . Harding" <me@...in.cc>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 4/9] vsprintf: Consolidate handling of unknown pointer
 specifiers

Hi Joe,

On (04/06/18 16:59), Joe Perches wrote:
> > 
> > Can we tweak checkpatch to catch such things?
> 
> Not really, no.
> 
> Adding regex logic for this is tricky at best
> and probably not worth the effort because of
> the various bits of patch contexts aren't
> necessarily visible.

Agreed. I was more thinking about catching "... %p" and saying
that we'd rather prefer either "... %p," or "... %p " or "... %p\n".
Doesn't sound so complex, can probably catch something fishy one day
(or may be not), and more or less is visible to checkpatch. Well,
more or less...

> There are also concatenations like
> 	"foo" DEFINE "bar"
> where DEFINE may not be visible in the patch
> context and checkpatch is and likely will
> remain just a limited regex checker.

Right. One example might be XFS

	alert("%s: Bad regular inode %Lu, ptr "PTR_FMT,
				__func__, ip->i_ino, ip);

where PTR_FMT is

#ifdef DEBUG
# define PTR_FMT "%px"
#else
# define PTR_FMT "%p"
#endif

	-ss