From mboxrd@z Thu Jan  1 00:00:00 1970
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Subject: Re: Do we still need devtree_lock?
From: Michael Ellerman <michael@ellerman.id.au>
To: Timur Tabi <timur@freescale.com>
In-Reply-To: <48617FA4.7070603@freescale.com>
References: <48617FA4.7070603@freescale.com>
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Date: Wed, 25 Jun 2008 09:25:28 +1000
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On Tue, 2008-06-24 at 18:13 -0500, Timur Tabi wrote:
> I'm trying to write a function that gets a list of all aliases
>=20
> 	aliases {
> 		serial0 =3D &serial0;
> 		serial1 =3D &serial1;
> 		pci0 =3D &pci0;
> 		pci1 =3D &pci1;
> 		pci2 =3D &pci2;
> 	};
>=20
> That is, I do not know which aliases are in the /aliases node, so I need =
a
> function that works somewhat like of_find_property(), but just returns th=
e Nth
> property instead of doing a strcmp.
>=20
> I can't seem to find one, so I probably need to write one.  However, I no=
ticed
> that of_find_property() uses a lock:
>=20
> 	read_lock(&devtree_lock);
> 	for (pp =3D np->properties; pp !=3D 0; pp =3D pp->next) {
> 		if (of_prop_cmp(pp->name, name) =3D=3D 0) {
> 			if (lenp !=3D 0)
> 				*lenp =3D pp->length;
> 			break;
> 		}
> 	}
> 	read_unlock(&devtree_lock);
>=20
> But the comment for devtree_lock says this:
>=20
> extern rwlock_t devtree_lock;	/* temporary while merging */
>=20
> Since arch/ppc is going away, does this meant that the lock can go away d=
o?

You wish :)  That /would/ make life easier.

I think the comment just refers to the extern declaration being in
the .c file, rather than a header - ie. now that the merge is done we
should clean it up and put it in a header.

cheers

--=20
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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