linux-kernel - Re: [PATCH 3/4] coredump: ELF-FDPIC: enable to omit anonymous shared memory

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Date:	Fri, 16 Feb 2007 15:05:35 +0000
From:	David Howells <dhowells@...hat.com>
To:	"Kawai, Hidehiro" <hidehiro.kawai.ez@...achi.com>
Cc:	Andrew Morton <akpm@...l.org>,
	kernel list <linux-kernel@...r.kernel.org>,
	Pavel Machek <pavel@....cz>, Robin Holt <holt@....com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	sugita <yumiko.sugita.yf@...achi.com>,
	Satoshi OSHIMA <soshima@...hat.com>,
	"Hideo AOKI@...hat" <haoki@...hat.com>
Subject: Re: [PATCH 3/4] coredump: ELF-FDPIC: enable to omit anonymous shared memory 

Kawai, Hidehiro <hidehiro.kawai.ez@...achi.com> wrote:

>  static int elf_fdpic_dump_segments(struct file *file, struct mm_struct *mm,
> -				   size_t *size, unsigned long *limit)
> +				   size_t *size, unsigned long *limit,
> +				   unsigned int omit_anon_shared)

Why are you passing it as an extra argument when you could just use
mm->coredump_omit_anon_shared here:

> +		if (!maydump(vma, omit_anon_shared))

And here:

> +		phdr.p_filesz = maydump(vma, omit_anon_shared) ? sz : 0;

Actually, I think I would just pass the mm pointer you have into maydump() and
let that dereference it here:

> +		if (omit_anon_shared) {

which would then be:

		if (mm->coredump_omit_anon_shared) {

Then the calls to maydump() would be:

		if (!maydump(vma, mm))

and:

		phdr.p_filesz = maydump(vma, current->mm) ? sz : 0;

I wouldn't worry, were I you, about the setting changing whilst it's being
used.  If you are worried about that, you can probably do some locking against
that.

David
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