| Message ID | 20220819094748.400578-2-danielhb413@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ppc/pnv: fix root port QOM parenting | expand |
On 19/08/2022 11:47, Daniel Henrique Barboza wrote: > We have 2 helpers that amends the QOM and parent bus of a given object, > repectively. These 2 helpers are called together, and not by accident. > Due to QOM internals, doing an object_unparent() will result in the > device being removed from its parent bus. This means that changing the > QOM parent requires reassigning the parent bus again. > > Create a single helper called pnv_parent_fixup(), documenting some of > the QOM specifics that we're dealing with the unparenting/parenting > mechanics, and handle both the QOM and the parent bus assignment. > > Next patch will make use of this function to handle a case where we need > to change the QOM parent while keeping the same parent bus assigned > beforehand. > > Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> > --- Thanks for the explanation. Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com> > hw/pci-host/pnv_phb.c | 43 ++++++++++++++++++++++++++++--------------- > 1 file changed, 28 insertions(+), 15 deletions(-) > > diff --git a/hw/pci-host/pnv_phb.c b/hw/pci-host/pnv_phb.c > index 17d9960aa1..4ea33fb6ba 100644 > --- a/hw/pci-host/pnv_phb.c > +++ b/hw/pci-host/pnv_phb.c > @@ -21,34 +21,45 @@ > > > /* > - * Set the QOM parent of an object child. If the device state > - * associated with the child has an id, use it as QOM id. Otherwise > - * use object_typename[index] as QOM id. > + * Set the QOM parent and parent bus of an object child. If the device > + * state associated with the child has an id, use it as QOM id. > + * Otherwise use object_typename[index] as QOM id. > + * > + * This helper does both operations at the same time because seting > + * a new QOM child will erase the bus parent of the device. This happens > + * because object_unparent() will call object_property_del_child(), > + * which in turn calls the property release callback prop->release if > + * it's defined. In our case this callback is set to > + * object_finalize_child_property(), which was assigned during the > + * first object_property_add_child() call. This callback will end up > + * calling device_unparent(), and this function removes the device > + * from its parent bus. > + * > + * The QOM and parent bus to be set aren´t necessarily related, so > + * let's receive both as arguments. > */ > -static void pnv_parent_qom_fixup(Object *parent, Object *child, int index) > +static bool pnv_parent_fixup(Object *parent, BusState *parent_bus, > + Object *child, int index, > + Error **errp) > { > g_autofree char *default_id = > g_strdup_printf("%s[%d]", object_get_typename(child), index); > const char *dev_id = DEVICE(child)->id; > > if (child->parent == parent) { > - return; > + return true; > } > > object_ref(child); > object_unparent(child); > object_property_add_child(parent, dev_id ? dev_id : default_id, child); > object_unref(child); > -} > - > -static void pnv_parent_bus_fixup(DeviceState *parent, DeviceState *child, > - Error **errp) > -{ > - BusState *parent_bus = qdev_get_parent_bus(parent); > > - if (!qdev_set_parent_bus(child, parent_bus, errp)) { > - return; > + if (!qdev_set_parent_bus(DEVICE(child), parent_bus, errp)) { > + return false; > } > + > + return true; > } > > /* > @@ -101,8 +112,10 @@ static bool pnv_phb_user_device_init(PnvPHB *phb, Error **errp) > * correctly the device tree. pnv_xscom_dt() needs every > * PHB to be a child of the chip to build the DT correctly. > */ > - pnv_parent_qom_fixup(parent, OBJECT(phb), phb->phb_id); > - pnv_parent_bus_fixup(DEVICE(chip), DEVICE(phb), errp); > + if (!pnv_parent_fixup(parent, qdev_get_parent_bus(DEVICE(chip)), > + OBJECT(phb), phb->phb_id, errp)) { > + return false; > + } > > return true; > }
diff --git a/hw/pci-host/pnv_phb.c b/hw/pci-host/pnv_phb.c index 17d9960aa1..4ea33fb6ba 100644 --- a/hw/pci-host/pnv_phb.c +++ b/hw/pci-host/pnv_phb.c @@ -21,34 +21,45 @@ /* - * Set the QOM parent of an object child. If the device state - * associated with the child has an id, use it as QOM id. Otherwise - * use object_typename[index] as QOM id. + * Set the QOM parent and parent bus of an object child. If the device + * state associated with the child has an id, use it as QOM id. + * Otherwise use object_typename[index] as QOM id. + * + * This helper does both operations at the same time because seting + * a new QOM child will erase the bus parent of the device. This happens + * because object_unparent() will call object_property_del_child(), + * which in turn calls the property release callback prop->release if + * it's defined. In our case this callback is set to + * object_finalize_child_property(), which was assigned during the + * first object_property_add_child() call. This callback will end up + * calling device_unparent(), and this function removes the device + * from its parent bus. + * + * The QOM and parent bus to be set aren´t necessarily related, so + * let's receive both as arguments. */ -static void pnv_parent_qom_fixup(Object *parent, Object *child, int index) +static bool pnv_parent_fixup(Object *parent, BusState *parent_bus, + Object *child, int index, + Error **errp) { g_autofree char *default_id = g_strdup_printf("%s[%d]", object_get_typename(child), index); const char *dev_id = DEVICE(child)->id; if (child->parent == parent) { - return; + return true; } object_ref(child); object_unparent(child); object_property_add_child(parent, dev_id ? dev_id : default_id, child); object_unref(child); -} - -static void pnv_parent_bus_fixup(DeviceState *parent, DeviceState *child, - Error **errp) -{ - BusState *parent_bus = qdev_get_parent_bus(parent); - if (!qdev_set_parent_bus(child, parent_bus, errp)) { - return; + if (!qdev_set_parent_bus(DEVICE(child), parent_bus, errp)) { + return false; } + + return true; } /* @@ -101,8 +112,10 @@ static bool pnv_phb_user_device_init(PnvPHB *phb, Error **errp) * correctly the device tree. pnv_xscom_dt() needs every * PHB to be a child of the chip to build the DT correctly. */ - pnv_parent_qom_fixup(parent, OBJECT(phb), phb->phb_id); - pnv_parent_bus_fixup(DEVICE(chip), DEVICE(phb), errp); + if (!pnv_parent_fixup(parent, qdev_get_parent_bus(DEVICE(chip)), + OBJECT(phb), phb->phb_id, errp)) { + return false; + } return true; }
We have 2 helpers that amends the QOM and parent bus of a given object, repectively. These 2 helpers are called together, and not by accident. Due to QOM internals, doing an object_unparent() will result in the device being removed from its parent bus. This means that changing the QOM parent requires reassigning the parent bus again. Create a single helper called pnv_parent_fixup(), documenting some of the QOM specifics that we're dealing with the unparenting/parenting mechanics, and handle both the QOM and the parent bus assignment. Next patch will make use of this function to handle a case where we need to change the QOM parent while keeping the same parent bus assigned beforehand. Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> --- hw/pci-host/pnv_phb.c | 43 ++++++++++++++++++++++++++++--------------- 1 file changed, 28 insertions(+), 15 deletions(-)