From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38727) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fTiG1-0003wa-3a for qemu-devel@nongnu.org; Fri, 15 Jun 2018 02:30:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fTiG0-0005a4-0J for qemu-devel@nongnu.org; Fri, 15 Jun 2018 02:30:49 -0400 Date: Fri, 15 Jun 2018 16:27:11 +1000 From: David Gibson Message-ID: <20180615062711.GT4129@umbus.fritz.box> References: <152901299450.252222.14219708016930421485.stgit@bahia.lan> <152901304242.252222.9947658955703347553.stgit@bahia.lan> <20180615000225.GC4129@umbus.fritz.box> <20180615075337.16f1fca0@bahia.lan> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="o6aug3O60clXg2rj" Content-Disposition: inline In-Reply-To: <20180615075337.16f1fca0@bahia.lan> Subject: Re: [Qemu-devel] [PATCH 3/5] spapr_cpu_core: add missing rollback on realization path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, =?iso-8859-1?Q?C=E9dric?= Le Goater --o6aug3O60clXg2rj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jun 15, 2018 at 07:53:37AM +0200, Greg Kurz wrote: > On Fri, 15 Jun 2018 10:02:25 +1000 > David Gibson wrote: >=20 > > On Thu, Jun 14, 2018 at 11:50:42PM +0200, Greg Kurz wrote: > > > The spapr_realize_vcpu() function doesn't rollback in case of error. > > > This isn't a problem with coldplugged CPUs because the machine won't > > > start and QEMU will exit. Hotplug is a different story though: the > > > CPU thread is started under object_property_set_bool() and it assumes > > > it can access the CPU object. > > >=20 > > > If icp_create() fails, we return an error without unregistering the > > > reset handler for this CPU, and we let the underlying QEMU thread for > > > this CPU alive. Since spapr_cpu_core_realize() doesn't care to unreal= ize > > > already realized CPUs either, but happily frees all of them anyway, t= he > > > CPU thread crashes instantly: > > >=20 > > > (qemu) device_add host-spapr-cpu-core,core-id=3D1,id=3Dgku > > > GKU: failing icp_create (cpu 0x11497fd0) > > > ^^^^^^^^^^ > > > Program received signal SIGSEGV, Segmentation fault. > > > [Switching to Thread 0x7fffee3feaa0 (LWP 24725)] > > > 0x00000000104c8374 in object_dynamic_cast_assert (obj=3D0x11497fd0, > > > ^^^^^^^^^^^^^^ > > > pointer to the CPU object > > > 623 trace_object_dynamic_cast_assert(obj ? obj->class->type->= name > > > (gdb) p obj->class->type > > > $1 =3D (Type) 0x0 > > > (gdb) p * obj > > > $2 =3D {class =3D 0x10ea9c10, free =3D 0x11244620, > > > ^^^^^^^^^^ > > > should be g_free > > > (gdb) p g_free > > > $3 =3D {} 0x7ffff282bef0 > > >=20 > > > obj is a dangling pointer to the CPU that was just destroyed in > > > spapr_cpu_core_realize(). > > >=20 > > > This patch adds proper rollback to both spapr_realize_vcpu() and > > > spapr_cpu_core_realize(). > > >=20 > > > Signed-off-by: Greg Kurz =20 > >=20 > > Applied to ppc-for-3.0, since it definitely looks to fix some > > problems. > >=20 > > > --- > > > hw/ppc/spapr_cpu_core.c | 12 ++++++++++-- > > > 1 file changed, 10 insertions(+), 2 deletions(-) > > >=20 > > > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c > > > index 003c4c5a79d2..04c818a6ecac 100644 > > > --- a/hw/ppc/spapr_cpu_core.c > > > +++ b/hw/ppc/spapr_cpu_core.c > > > @@ -159,12 +159,16 @@ static void spapr_realize_vcpu(PowerPCCPU *cpu,= sPAPRMachineState *spapr, > > > spapr_cpu->icp =3D icp_create(OBJECT(cpu), spapr->icp_type, > > > XICS_FABRIC(spapr), &local_err); > > > if (local_err) { > > > - goto error; > > > + goto error_unregister; > > > } > > > =20 > > > return; > > > =20 > > > +error_unregister: > > > + qemu_unregister_reset(spapr_cpu_reset, cpu); > > > + cpu_remove_sync(CPU(cpu)); =20 > >=20 > > I'm a little unclear on exactly what init the cpu_remove_sync() is > > mirroring, though. > >=20 >=20 > We have the same call in spapr_unrealize_vcpu(). IIUC it is mirroring > object_property_set_bool(OBJECT(cpu), true, "realized", &local_err). Ok. >=20 > > > error: > > > + g_free(spapr_cpu); > > > error_propagate(errp, local_err); > > > } > > > =20 > > > @@ -222,11 +226,15 @@ static void spapr_cpu_core_realize(DeviceState = *dev, Error **errp) > > > for (j =3D 0; j < cc->nr_threads; j++) { > > > spapr_realize_vcpu(sc->threads[j], spapr, &local_err); > > > if (local_err) { > > > - goto err; > > > + goto err_unrealize; > > > } > > > } > > > return; > > > =20 > > > +err_unrealize: > > > + while (--j >=3D 0) { > > > + spapr_unrealize_vcpu(sc->threads[i]); > > > + } > > > err: > > > while (--i >=3D 0) { > > > obj =3D OBJECT(sc->threads[i]); > > > =20 > >=20 >=20 --=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 --o6aug3O60clXg2rj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlsjXDwACgkQbDjKyiDZ s5LPcw//aLCkoSkNt0ylmSP9cwe8osqF9vxAE6it81kzyyxoNwoDsJBBZHYkap6Z Eb9O+1+WIDJxye5UgOrn0R/fiDZ5v0gEPbUuanyhsJ/hcAnaHpIh+sol4yUgjj5K WK0nyl8LbaY2uWvLh47eQ1zU5xrt2ndFJ7bT8FaOh0GG3KyMPXR5nsZUL9B5f4ls P4ZU4Ov7gh7fhWx4C1pkzMXFKfxFsYO98MleGPLs31G4MikKfempYgh+FKF95ZWd vVhyFoSlh/X0fw2Lczb2LnVWk7g7B0ajR3a/aH1OzcseuzlCfCvTFvFwXCrIxIzM /jGnZdW7vChwFv6hhjfF9ZQMHbh6NS4zHiFZ/nFNVHXsGKMhPbIffV2KcRfWqBxL MQIbmiK7ytYBZsSluQOo00fx6+Ts1I76BlV9vofIGHNQqNhxoGil1iwN5ULJqttJ a7pKnH5634N4QHpjyYt3+sUraVPQmqOz7TVA5g+Np/8IL9GhN3mLIOXPLtpIIzyC KFv5f2diZNByWUrPW8QFoB/O9/Fp2yx/ze6VW2P1qrIoVya9QkCC+ApELnpPMYIg 97pujl9NvHd0sxm3u+z18gaCAgBw1A4B546cdyx2AQevv2II9CvgIoZOr7S+yTem kVxsgX4VSrjKMKjVDRAPbPMftWV+DzmRfBi7jMHKBLY1IHy//6Q= =xEYZ -----END PGP SIGNATURE----- --o6aug3O60clXg2rj--