linux-kernel - Re: [PATCH][resubmit] TPM: update char dev BKL pushdown

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Message-ID: <20080827031948.GA5184@us.ibm.com>
Date:	Tue, 26 Aug 2008 22:19:48 -0500
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, zohar@...ibm.com,
	dvelarde@...ibm.com, safford@...ibm.com
Subject: Re: [PATCH][resubmit] TPM: update char dev BKL pushdown

Quoting Alan Cox (alan@...rguk.ukuu.org.uk):
> > +	atomic_set(&chip->is_open, 1);
> > +	get_device(chip->dev); /* protect from chip disappearing */
> 
> Why not just use test_and_set_bit() ? You seem to be abusing atomic_t to
> achieve this.

Good point.  Or heck just make it a simple flag.  Earlier I thought there
was a place where driver_lock was taken just to do num_opens--, and so
replacing the int num_opens with an atomic_t seemed worthwhile.  But since
is_open is a boolean and now seems to be always protected by driver_lock,
a flag seems best.

-serge
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