From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39122) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1csf7j-0002Ah-2T for qemu-devel@nongnu.org; Mon, 27 Mar 2017 20:36:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1csf7h-00074a-RM for qemu-devel@nongnu.org; Mon, 27 Mar 2017 20:36:35 -0400 Received: from ozlabs.org ([2401:3900:2:1::2]:46651) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1csf7g-0006zI-Sn for qemu-devel@nongnu.org; Mon, 27 Mar 2017 20:36:33 -0400 Date: Tue, 28 Mar 2017 11:06:28 +1100 From: David Gibson Message-ID: <20170328000628.GA13461@umbus.fritz.box> References: <20170327044030.31306-1-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="oyUTqETQ0mS9luUI" Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH qemu] pci: Add missing drop of bus master AS reference List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Alexey Kardashevskiy , qemu-devel@nongnu.org, Marcel Apfelbaum , "Michael S . Tsirkin" , Jason Wang , Peter Maydell --oyUTqETQ0mS9luUI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Mar 27, 2017 at 05:28:17PM +0200, Paolo Bonzini wrote: >=20 >=20 > On 27/03/2017 06:40, Alexey Kardashevskiy wrote: > > The recent introduction of a bus master container added > > memory_region_add_subregion() into the PCI device registering path but > > missed memory_region_del_subregion() in the unregistering path leaving > > a reference to the root memory region of the new container. > >=20 > > This adds missing memory_region_del_subregion(). > >=20 > > Fixes: 3716d5902d743 ("pci: introduce a bus master container") > > Signed-off-by: Alexey Kardashevskiy > > --- > > hw/pci/pci.c | 2 ++ > > 1 file changed, 2 insertions(+) > >=20 > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c > > index e6b08e1988..bd8043c460 100644 > > --- a/hw/pci/pci.c > > +++ b/hw/pci/pci.c > > @@ -869,6 +869,8 @@ static void do_pci_unregister_device(PCIDevice *pci= _dev) > > pci_dev->bus->devices[pci_dev->devfn] =3D NULL; > > pci_config_free(pci_dev); > > =20 > > + memory_region_del_subregion(&pci_dev->bus_master_container_region, > > + &pci_dev->bus_master_enable_region); > > address_space_destroy(&pci_dev->bus_master_as); > > } > > =20 > >=20 >=20 > My own review fail. The enable subregion would be deleted when a memory > region is finalized, but the enable subregions is keeping the owner > alive. And until the owner is alive, the container region is not > deleted either. So there is a reference count cycle, which we need to > break. >=20 > It's probably good to revisit commit 2e2b8eb ("memory: allow destroying > a non-empty MemoryRegion", 2015-10-01). For 2.9, >=20 > Reviewed-by: Paolo Bonzini Merged to ppc-for-2.9. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --oyUTqETQ0mS9luUI Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJY2akCAAoJEGw4ysog2bOSB64QAKL10yYcULN+YjCvYvMJZXho vwpyWLDiD+fAcj0Gp5U6o/2OAtbd7+uSQpHmkAsHpXEFrAEqS+rv2sbbsLYRvVEn dOdFpC80qcF9NXenDhBFLxHNT8nAvNnSMYrVFNb23ooMEa1Cqc5myROeaLuPrbOv aSEyktdFUj8hw1XqhtTfA5iZ+swUKufUSs7KUcaJX7hUBJb4ttBI7vTBP3SLNaVB WJV0qpYSXPx8VF18JrWWzoCgpC80zQilrA4VJjWAdG+C1jK8zj3584WdEQ5uqhNf iknHoWmIfeKRYgflMHQZIC05cr79YZbuECg03hUbltQxb6qjtJF2XLQ2GjviH/28 yA48CmTcR6Pu9isOXSqi3H4R5t7f5ylFAT4u+fMckJiAlWlUBUzd1vm1PCWCtvTk 7cncRSQxBMvlY+9XUDrXWgevoWqiO36AHc+EDIGbIg6kiE9I9i4j9lPPfrP5etKT MxvD7+qAZ8QQRulJtwbJN8yTreU1ERw2msCm3XZTXaY4JH6BOyLIJeNmITNB+wOw 20YRS9QM6A2zA6+Wm4isrYsTFqk64UVt+H8H/D/mPG16nIOuSvUGwvjKfVau7xqQ 89Warqa+krgYAFW0L5gt2+zaAPDOgbXmXjzctZgxY/o7g6IPOmkVdTDloZtOdTf5 bSULN8EusBTNdAb9mp3d =tHJ3 -----END PGP SIGNATURE----- --oyUTqETQ0mS9luUI--