linux-kernel - Re: [PATCH] module: make it clearer when we're handling kallsyms symbols vs exported symbols

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Message-ID: <20181122130038.GA21394@linux-8ccs>
Date:   Thu, 22 Nov 2018 14:00:39 +0100
From:   Jessica Yu <jeyu@...nel.org>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: make it clearer when we're handling kallsyms
 symbols vs exported symbols

+++ Miroslav Benes [22/11/18 11:19 +0100]:
>On Wed, 21 Nov 2018, Jessica Yu wrote:
>
>> The module loader internally works with both exported symbols
>> represented as struct kernel_symbol, as well as Elf symbols from a
>> module's symbol table. It's hard to distinguish sometimes which type of
>> symbol we're handling given that some helper function names are not
>> consistent or helpful. Take get_ksymbol() for instance - are we
>> looking for an exported symbol or a kallsyms symbol here? Or symname()
>> and kernel_symbol_name() - which function handles an exported symbol and
>> which one an Elf symbol?
>>
>> Clean up and unify the function naming scheme a bit to make it clear
>> which kind of symbol we're handling. This change only affects static
>> functions internal to the module loader.
>>
>> Signed-off-by: Jessica Yu <jeyu@...nel.org>
>
>Great. It should help a lot. Pity we cannot rename find_symbol() as well.
>
>I have only a naming nit. I think it is nice to have
><verb>_exported_<noun> convention. New kallsyms_ names don't hold it
>though. Wouldn't it be better to be consistent and have
>find_kallsyms_symbol() instead of kallsyms_find_symbol()? Or we could do
>the opposite and have a "namespace" prefix first. That is,
>exported_<verb>_<noun>. However, I don't like it that much.
>
>To be honest, your approach may be the best in the end.
>
>What do you think?

Hi Miroslav, thank you for the comment!

Yeah, that bothered me partially too. And a lot of existing helper
functions in the module loader already have a <verb>_ type prefix.

Hm, how about we use <symbol_type>_* prefixes if we are just extracting a
value, and <verb>_* prefixes for functions actually performing an
action? 

Kallsyms:

   kallsyms_symbol_name()
   kallsyms_symbol_value()
   
   find_kallsyms_symbol()
   find_kallsyms_symbol_value()
 
   etc.

Exported syms:

   kernel_symbol_name()
   kernel_symbol_value()
   
   lookup_exported_symbol()
   check_exported_symbol()
 
   etc.

I had left the kernel_symbol_* functions alone since I guess they do
describe what they're handling, they're handling struct kernel_symbol's.
But maybe I will change that to exported_symbol_name() and
exported_symbol_value() to be consistent with the naming scheme..

Thanks!

Jessica