linux-kernel - Re: [PATCH] x86: Fix io_bitmap_ptr memory leak on copy

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Date:	Mon, 14 Feb 2011 18:27:20 +0900
From:	Tadashi Abe <tabe@...sta.com>
To:	Jesper Juhl <jj@...osbits.net>
CC:	x86@...nel.org, tglx@...utronix.de, hpa@...or.com,
	mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Fix io_bitmap_ptr memory leak on copy_process()

>>> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
>>> index b3feabc..290e98b 100644
>>> --- a/arch/x86/kernel/process.c
>>> +++ b/arch/x86/kernel/process.c
>>> @@ -122,6 +122,12 @@ void flush_thread(void)
>>>  	clear_used_math();
>>>  }
>>>  
>>> +void free_thread_struct(struct task_struct *p)
>>> +{
>>> +	if (p->thread.io_bitmap_ptr)
>>> +		kfree(p->thread.io_bitmap_ptr);
>>
>> kfree(NULL) is perfectly legal, so the 'if' is not needed.

Thanks. agreed.

>> Why is this a new function? Why not simply call kfree() when needed.

io_bitmap_ptr is a x86 specific variable
so I didn't think it should be in generic kernel codes (kernel/fork.c).
I understand making a new function looks overkill though.
Even if you call kfree() directly in kernel/fork.c,
"#ifdef CONFIG_X86" is necessary anyway.

But I don't have any insistence on how to fix it and leave it to experts' choice.

Thanks
--
Tadashi
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