Re: [Qemu-devel] [PATCH 1/2] ide: core: add cleanup function

[John Snow]

On 02/28/2017 08:03 PM, Li Qiang wrote:
> Hello John, Paolo,
> 
> 2017-03-01 8:47 GMT+08:00 John Snow <address@hidden
> <mailto:address@hidden>>:
> 
> 
> 
>     On 02/09/2017 02:04 AM, Li Qiang wrote:
>     > As the pci ahci can be hotplug and unplug, in the ahci unrealize
>     > function it should free all the resource once allocated in the
>     > realized function. This patch adds two cleanup function.
>     >
> 
>     So, the peculiarities of the current arrangement of QDEV realization and
>     unrealization is a bit of a mystery to me, so I'm hoping my suggestions
>     here make sense.
> 
>     > Signed-off-by: Li Qiang <address@hidden <mailto:address@hidden>>
>     > ---
>     >  hw/ide/core.c             | 21 +++++++++++++++++++++
>     >  include/hw/ide/internal.h |  2 ++
>     >  2 files changed, 23 insertions(+)
>     >
>     > diff --git a/hw/ide/core.c b/hw/ide/core.c
>     > index 43709e5..8fe5896 100644
>     > --- a/hw/ide/core.c
>     > +++ b/hw/ide/core.c
>     > @@ -2586,6 +2586,13 @@ void ide_register_restart_cb(IDEBus *bus)
>     >      }
>     >  }
>     >
>     > +void ide_unregister_restart_cb(IDEBus *bus)
>     > +{
>     > +    if (bus->dma->ops->restart_dma) {
>     > +        qemu_del_vm_change_state_handler(bus->vmstate);
>     > +    }
>     > +}
>     > +
> 
>     This works perfectly well, though I think the function is named
>     incorrectly -- this should be an AHCI function, as it is AHCI's job to
>     unregister the IDEBus it created (not IDE's -- the bus belongs to the
>     HBA, not the IDE device.)
> 
>     However, we DO have the IDEBus unrealize code in qdev.c that should be
>     handling this for us. Can we rename this function and just have it set
>     the "realized" property of the IDEBus to false to handle this cleanup
>     for us?
> 
>     I'm not well versed in qdev code management, but it definitely feels
>     wrong to have the cleanup in two places.
> 
> 
>  Agree, but I'm not familiar with qdev too, that's why we need Paolo's help.
> 
> @Paolo,
> Could you please have a look at this issue?
> 
> 

OK, so here's what it looks like to me from here:

we have an idebus unrealize function, but it was being registered as the
unrealize function for the IDE Device, so it was not getting invoked on
device teardown because nothing is "unrealizing" the IDE devices
themselves, AFAIK.

Perhaps what we want is this, which does actually do the proper bus
teardown:

-static void idebus_unrealize(DeviceState *qdev, Error **errp);
+static void idebus_unrealize(BusState *bus, Error **errp);

 static Property ide_props[] = {
     DEFINE_PROP_UINT32("unit", IDEDevice, unit, -1),
@@ -43,14 +43,17 @@ static void ide_bus_class_init(ObjectClass *klass,
void *data)
     BusClass *k = BUS_CLASS(klass);

     k->get_fw_dev_path = idebus_get_fw_dev_path;
+    k->unrealize = idebus_unrealize;
 }

-static void idebus_unrealize(DeviceState *qdev, Error **errp)
+static void idebus_unrealize(BusState *bus, Error **errp)
 {
-    IDEBus *bus = DO_UPCAST(IDEBus, qbus, qdev->parent_bus);
-
-    if (bus->vmstate) {
-        qemu_del_vm_change_state_handler(bus->vmstate);
+    IDEBus *ibus = IDE_BUS(bus);
+    if (ibus->vmstate) {
+        qemu_del_vm_change_state_handler(ibus->vmstate);
     }
 }
@@ -365,7 +369,6 @@ static void ide_device_class_init(ObjectClass
*klass, void *data)
     k->init = ide_qdev_init;
     set_bit(DEVICE_CATEGORY_STORAGE, k->categories);
     k->bus_type = TYPE_IDE_BUS;
-    k->unrealize = idebus_unrealize;
     k->props = ide_props;
 }



This way the bus teardown calls the existing handler. If you integrate
this into your patches and recreate ide_exit as a per-device teardown
function, I'll merge this.

Thanks for your patience and the bug report,
--John

>     >  static IDEDMA ide_dma_nop = {
>     >      .ops = &ide_dma_nop_ops,
>     >      .aiocb = NULL,
>     > @@ -2603,6 +2610,20 @@ void ide_init2(IDEBus *bus, qemu_irq irq)
>     >      bus->dma = &ide_dma_nop;
>     >  }
>     >
>     > +void ide_exit(IDEBus *bus)
>     > +{
>     > +    int i;
>     > +
>     > +    for (i = 0; i < 2; i++) {
>     > +        IDEState *s = &bus->ifs[i];
>     > +
>     > +        timer_del(s->sector_write_timer);
>     > +        timer_free(s->sector_write_timer);
>     > +        qemu_vfree(s->smart_selftest_data);
>     > +        qemu_vfree(s->io_buffer);
> 
>     I would prefer a function that cleans up a single IDE device, and the
>     caller (which has knowledge of the HBA and the buses it owns) loops as
>     appropriate. (In this case, ahci_uninit or ahci_unrealize or whichever.)
> 
>     It's correct otherwise, though.
> 
>     > +    }
>     > +}
>     > +
>     >  static const MemoryRegionPortio ide_portio_list[] = {
>     >      { 0, 8, 1, .read = ide_ioport_read, .write = ide_ioport_write },
>     >      { 0, 1, 2, .read = ide_data_readw, .write = ide_data_writew },
>     > diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
>     > index 88dc118..09b0404 100644
>     > --- a/include/hw/ide/internal.h
>     > +++ b/include/hw/ide/internal.h
>     > @@ -607,8 +607,10 @@ int ide_init_drive(IDEState *s, BlockBackend
>     *blk, IDEDriveKind kind,
>     >                     uint32_t cylinders, uint32_t heads, uint32_t secs,
>     >                     int chs_trans);
>     >  void ide_init2(IDEBus *bus, qemu_irq irq);
>     > +void ide_exit(IDEBus *bus);
>     >  void ide_init_ioport(IDEBus *bus, ISADevice *isa, int iobase, int
>     iobase2);
>     >  void ide_register_restart_cb(IDEBus *bus);
>     > +void ide_unregister_restart_cb(IDEBus *bus);
>     >
>     >  void ide_exec_cmd(IDEBus *bus, uint32_t val);
>     >
>     >
> 
>