linux-kernel - Re: [PATCH 0/3] pstore: pass allocated memory region back to caller

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Message-ID: <CAGXu5jKbBfSK5njG-HY9bsPwcOWN_TzWTLfQftNQREBQeG8HXA@mail.gmail.com>
Date:	Mon, 14 Nov 2011 16:45:55 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Tony Luck <tony.luck@...il.com>
Cc:	linux-kernel@...r.kernel.org, Matthew Garrett <mjg@...hat.com>
Subject: Re: [PATCH 0/3] pstore: pass allocated memory region back to caller

On Mon, Nov 14, 2011 at 3:55 PM, Tony Luck <tony.luck@...il.com> wrote:
> On Mon, Nov 14, 2011 at 3:12 PM, Kees Cook <keescook@...omium.org> wrote:
>> Since pstore's buf_lock cannot be held while doing the VFS population,
>> these patches make it the backend's responsibility to pass up an allocated
>> buffer instead during reads.
>
> The split into three parts is good for review purposes - but I'll
> squish them all together
> into one commit to avoid breaking bisectability.

Okay, sounds good.

> I'm trying to work out whether I should be worried about the removal
> of the locks
> around the:
>
>   (*open)(...)
>   while (size = (*read)(...)) {
>   }
>   (*close)()
>
> section in pstore_get_records().  If someone tries to simultaneously mount
> pstore in multiple places - will the upper level mount code serialize? I don't
> think the backends will be happy if multiple callers execute that at the same
> time.

How should it be handled? We can't hold any lock while doing the VFS work.

-Kees

-- 
Kees Cook
ChromeOS Security
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