linux-kernel - Re: [PATCH] kprobes: disable preempt for module_text

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Date:	Wed, 05 Nov 2008 18:07:49 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
CC:	Lai Jiangshan <laijs@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>, ananth@...ibm.com,
	David Miller <davem@...emloft.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kprobes: disable preempt for module_text_address()

Hiroshi Shimamoto wrote:
>>  	if (probed_mod) {
>> -		struct module *calling_mod = module_text_address(called_from);
>> +		struct module *calling_mod;
>> +		calling_mod = __module_text_address(called_from);
>>  		/*
>>  		 * We must allow modules to probe themself and in this case
>>  		 * avoid incrementing the module refcount, so as to allow
>>  		 * unloading of self probing modules.
>>  		 */
>>  		if (calling_mod && calling_mod != probed_mod) {
> 
> One question, off topic.
> If calling_mod is NULL, no try_module_get(), is that OK?

Good question. Currently, kprobes is called only from kernel modules,
so calling_mod should be always !NULL.
However, it should be fixed, because the logic is not correct.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

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