linux-kernel - Re: [PATCH 0/4] IMA: making i_readcount a first class inode citizen

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Message-ID: <AANLkTimvEAj2SL7RrwTdypGA_PYJcZyw8OMBGckWpVs7@mail.gmail.com>
Date:	Thu, 28 Oct 2010 15:46:04 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	Dave Chinner <david@...morbit.com>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, hch@...radead.org,
	warthog9@...nel.org, jmorris@...ei.org, kyle@...artin.ca,
	hpa@...or.com, akpm@...ux-foundation.org, mingo@...e.hu,
	eparis@...hat.com, viro@...iv.linux.org.uk,
	Matthew Wilcox <matthew@....cx>
Subject: Re: [PATCH 0/4] IMA: making i_readcount a first class inode citizen

On Thu, Oct 28, 2010 at 3:38 PM, Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
>
> Would making i_readcount atomic be enough in ima_rdwr_violation_check(),
> or would it still need to take the spin_lock? IMA needs guarantees
> that the i_readcount/i_writecount won't be updated in between.

If i_writecount is always updated under the i_lock, then the fix is
probably to make that one non-atomic instead. There's no point in
having an atomic that is always updated under a spinlock, that just
makes everything slower.

Regardless, I don't think i_readcount should be different from i_writecount.

Al? Comments?

                  Linus
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