linux-kernel - Re: [PATCH 0/5] [RFC] printk/ia64/ppc64/parisc64: let's deprecate %pF/%pf printk specifiers

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Date:   Tue, 19 Sep 2017 22:07:31 +0200
From:   Helge Deller <deller@....de>
To:     David Laight <David.Laight@...LAB.COM>,
        'Sergey Senozhatsky' <sergey.senozhatsky.work@...il.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>, Jessica Yu <jeyu@...nel.org>,
        "James E . J . Bottomley" <jejb@...isc-linux.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/5] [RFC] printk/ia64/ppc64/parisc64: let's deprecate
 %pF/%pf printk specifiers

On 19.09.2017 15:38, David Laight wrote:
> From: Sergey Senozhatsky
>> Sent: 19 September 2017 03:06
> ...
>> I'll simply convert everything to `unsigned long'. including the
>> dereference_function_descriptor() function [I believe there are
>> still some casts happening when we pass addr from kernel/module
>> dereference functions to dereference_function_descriptor(), or
>> when we return `void *' back to symbol resolution code, etc.)
>> besides, it seems that everything that uses
>> dereference_function_descriptor() wants `unsigned long' anyway:
> 
> Using 'unsigned long' for any kind of pointer is an accident
> waiting do happen.
> It also makes it difficult to typecheck the function calls.
> Using 'void *' isn't any better.
> Either a pointer to an undefined struct, or a struct containing
> a single 'char' member, is likely to be safest.

David, you might be right in most cases, but in this case I'd prefer
unsigned long too. I think this will create the least amount of
typecasts here.

Helge