From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dario Faggioli <dario.faggioli@citrix.com>
Subject: Re: [PATCH 0/5] use mask operations instead of
	test_bit()
Date: Fri, 2 Oct 2015 11:33:42 +0200
Message-ID: <1443778422.14525.49.camel@citrix.com>
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To: Juergen Gross <jgross@suse.com>
Cc: george.dunlap@eu.citrix.com, andrew.cooper3@citrix.com, keir@xen.org, jbeulich@suse.com, xen-devel <xen-devel@lists.xen.org>
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On Fri, 2015-10-02 at 11:10 +0200, Juergen Gross wrote:
> On 10/02/2015 11:03 AM, Dario Faggioli wrote:

> > That's a good idea, I think.
>=20
> It's a fallout from a cleanup patch:
>=20
> http://lists.xen.org/archives/html/xen-devel/2015-09/msg03184.html
>=20

> > One question, can we introduce a __test_bit() macro/inline
> > function,
> > like Jan did with __set_bit?
>=20
> In the thread mentioned above you'll find a discussion about exactly
> this idea between Jan and me.
>=20
Ah, I see. Sorry, I missed it.

> > I've quickly-&-dirtily tested this:
> >=20
> > #define __test_bit(nr, addr) ({  \
> >      unsigned _flags =3D 1 << nr;   \
> >      addr & _flags; \
> > })
> >=20
> > and the result (I've checked a couple of cases) seems the same to
> > me.
>=20
> The problem is the limited scope where this scheme is really working
> and
> is a better solution at the same time (nr must be a constant less
> than
> the numbers of bits of *addr).
>=20
Right, so we could only use __test_bit() in a subset of the cases,
i.e., we won't gain that much more consistency... I see it now.

Regards,
Dario
--=20
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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