On Fri, 13 Oct 2017 11:21:20 +0200
Igor Mammedov <imamm...@redhat.com> wrote:
> On Fri, 13 Oct 2017 10:35:19 +0200
> Greg Kurz <gr...@kaod.org> wrote:
>
> > The current code assumes that only the CPU core object holds a
> > reference on each individual CPU object, and happily frees their
> > allocated memory when the core is unrealized. This is dangerous
> > as some other code can legitimely keep a pointer to a CPU if it
> > calls object_ref(), but it would end up with a dangling pointer.
> >
> > Let's allocate all CPUs with object_new() and let QOM frees them
> > when their reference count reaches zero.
> I agree with patch as it simplifies code and one doesn't have to
> fiddle wit size anymore.
Yes, I'll mention that in the changelog as well.
> See some comments below.
>
> >
> > Signed-off-by: Greg Kurz <gr...@kaod.org>
> > ---
> > hw/ppc/spapr.c | 10 +++-------
> > hw/ppc/spapr_cpu_core.c | 29 +++++++++--------------------
> > include/hw/ppc/spapr_cpu_core.h | 2 +-
> > 3 files changed, 13 insertions(+), 28 deletions(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index fd9813bde82f..ba391c6ed5de 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -3153,12 +3153,10 @@ void spapr_core_release(DeviceState *dev)
> >
> > if (smc->pre_2_10_has_unused_icps) {
> > sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> > - sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(cc));
> > - size_t size = object_type_get_instance_size(scc->cpu_type);
> > int i;
> >
> > for (i = 0; i < cc->nr_threads; i++) {
> > - CPUState *cs = CPU(sc->threads + i * size);
> > + CPUState *cs = CPU(sc->threads[i]);
> >
> > pre_2_10_vmstate_register_dummy_icp(cs->cpu_index);
> > }
> > @@ -3204,7 +3202,7 @@ static void spapr_core_plug(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> > sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> > CPUCore *cc = CPU_CORE(dev);
> > - CPUState *cs = CPU(core->threads);
> > + CPUState *cs = CPU(core->threads[0]);
> > sPAPRDRConnector *drc;
> > Error *local_err = NULL;
> > int smt = kvmppc_smt_threads();
> > @@ -3249,13 +3247,11 @@ static void spapr_core_plug(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > core_slot->cpu = OBJECT(dev);
> >
> > if (smc->pre_2_10_has_unused_icps) {
> > - sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(cc));
> > - size_t size = object_type_get_instance_size(scc->cpu_type);
> > int i;
> >
> > for (i = 0; i < cc->nr_threads; i++) {
> > sPAPRCPUCore *sc = SPAPR_CPU_CORE(dev);
> > - void *obj = sc->threads + i * size;
> > + void *obj = sc->threads[i];
> >
> > cs = CPU(obj);
> > pre_2_10_vmstate_unregister_dummy_icp(cs->cpu_index);
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index 3a4c17401226..47c408b52ca1 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -79,21 +79,18 @@ const char *spapr_get_cpu_core_type(const char
> > *cpu_type)
> > static void spapr_cpu_core_unrealizefn(DeviceState *dev, Error **errp)
> > {
> > sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> > - sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(dev));
> > - size_t size = object_type_get_instance_size(scc->cpu_type);
> > CPUCore *cc = CPU_CORE(dev);
> > int i;
> >
> > for (i = 0; i < cc->nr_threads; i++) {
> > - void *obj = sc->threads + i * size;
> > - DeviceState *dev = DEVICE(obj);
> > + DeviceState *dev = DEVICE(sc->threads[i]);
> > CPUState *cs = CPU(dev);
> > PowerPCCPU *cpu = POWERPC_CPU(cs);
> >
> > spapr_cpu_destroy(cpu);
> > object_unparent(cpu->intc);
> > cpu_remove_sync(cs);
> > - object_unparent(obj);
> > + object_unparent(sc->threads[i]);
> > }
> > g_free(sc->threads);
> > }
> > @@ -146,9 +143,7 @@ static void spapr_cpu_core_realize(DeviceState *dev,
> > Error **errp)
> > sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> > sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(dev));
> > CPUCore *cc = CPU_CORE(OBJECT(dev));
> > - size_t size;
> > Error *local_err = NULL;
> > - void *obj;
> > int i, j;
> >
> > if (!spapr) {
> > @@ -156,17 +151,14 @@ static void spapr_cpu_core_realize(DeviceState *dev,
> > Error **errp)
> > return;
> > }
> >
> > - size = object_type_get_instance_size(scc->cpu_type);
> > - sc->threads = g_malloc0(size * cc->nr_threads);
> > + sc->threads = g_new(void *, cc->nr_threads);
>
> ^^^ PowerPCCPU*
>
Right, I guess void * was appropriate to do the pointer arithmetics but we don't
need that anymore.
> and maybe g_new0() if incomplete cores are possible.
>
Yes, older machine types (ie, that don't support CPU hotplug) can have
incomplete cores, but cc->nr_threads is set to the actual number of
threads in this case. See spapr_init_cpus() in hw/ppc/spapr.c.
> > for (i = 0; i < cc->nr_threads; i++) {
> > char id[32];
> > CPUState *cs;
> > PowerPCCPU *cpu;
> >
> > - obj = sc->threads + i * size;
> > -
> > - object_initialize(obj, size, scc->cpu_type);
> > - cs = CPU(obj);
> > + sc->threads[i] = object_new(scc->cpu_type);
> > + cs = CPU(sc->threads[i]);
> > cpu = POWERPC_CPU(cs);
> > cs->cpu_index = cc->core_id + i;
> > cpu->vcpu_id = (cc->core_id * spapr->vsmt / smp_threads) + i;
> > @@ -184,17 +176,15 @@ static void spapr_cpu_core_realize(DeviceState *dev,
> > Error **errp)
> > cpu->node_id = sc->node_id;
> >
> > snprintf(id, sizeof(id), "thread[%d]", i);
> > - object_property_add_child(OBJECT(sc), id, obj, &local_err);
> > + object_property_add_child(OBJECT(sc), id, sc->threads[i],
> > &local_err);
> > if (local_err) {
> > goto err;
> > }
> > - object_unref(obj);
> > + object_unref(sc->threads[i]);
> > }
> >
> > for (j = 0; j < cc->nr_threads; j++) {
> > - obj = sc->threads + j * size;
> > -
> > - spapr_cpu_core_realize_child(obj, spapr, &local_err);
> > + spapr_cpu_core_realize_child(sc->threads[j], spapr, &local_err);
> > if (local_err) {
> > goto err;
> > }
> > @@ -203,8 +193,7 @@ static void spapr_cpu_core_realize(DeviceState *dev,
> > Error **errp)
> >
> > err:
> > while (--i >= 0) {
> > - obj = sc->threads + i * size;
> > - object_unparent(obj);
> > + object_unparent(sc->threads[i]);
> > }
> > g_free(sc->threads);
> > error_propagate(errp, local_err);
> > diff --git a/include/hw/ppc/spapr_cpu_core.h
> > b/include/hw/ppc/spapr_cpu_core.h
> > index f2d48d6a6786..f5b943a6682c 100644
> > --- a/include/hw/ppc/spapr_cpu_core.h
> > +++ b/include/hw/ppc/spapr_cpu_core.h
> > @@ -28,7 +28,7 @@ typedef struct sPAPRCPUCore {
> > CPUCore parent_obj;
> >
> > /*< public >*/
> > - void *threads;
> > + void **threads;
> ditto, should be PowerPCCPU
>
Ok.
Thanks for the feedback!
> > int node_id;
> > } sPAPRCPUCore;
> >
> >
> >
>
