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Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of l
From: |
David Hildenbrand |
Subject: |
Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge |
Date: |
Mon, 5 Nov 2018 12:50:00 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 |
On 05.11.18 12:40, Christian Borntraeger wrote:
>
>
> On 11/05/2018 12:37 PM, David Hildenbrand wrote:
>> On 05.11.18 12:21, Cornelia Huck wrote:
>>> On Mon, 5 Nov 2018 12:03:11 +0100
>>> David Hildenbrand <address@hidden> wrote:
>>>
>>>> We directly have it in our hands.
>>>>
>>>> Signed-off-by: David Hildenbrand <address@hidden>
>>>> ---
>>>> hw/s390x/s390-pci-bus.c | 4 ++--
>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
>>>> index 1eaae3aca6..68660eac74 100644
>>>> --- a/hw/s390x/s390-pci-bus.c
>>>> +++ b/hw/s390x/s390-pci-bus.c
>>>> @@ -814,9 +814,9 @@ static bool s390_pci_alloc_idx(S390pciState *s,
>>>> S390PCIBusDevice *pbdev)
>>>> static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState
>>>> *dev,
>>>> Error **errp)
>>>> {
>>>> + S390pciState *s = S390_PCI_HOST_BRIDGE(hotplug_dev);
>>>> PCIDevice *pdev = NULL;
>>>> S390PCIBusDevice *pbdev = NULL;
>>>> - S390pciState *s = s390_get_phb();
>>>>
>>>> if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
>>>> BusState *bus;
>>>> @@ -924,11 +924,11 @@ static void s390_pcihost_timer_cb(void *opaque)
>>>> static void s390_pcihost_unplug(HotplugHandler *hotplug_dev, DeviceState
>>>> *dev,
>>>> Error **errp)
>>>> {
>>>> + S390pciState *s = S390_PCI_HOST_BRIDGE(hotplug_dev);
>>>> PCIDevice *pci_dev = NULL;
>>>> PCIBus *bus;
>>>> int32_t devfn;
>>>> S390PCIBusDevice *pbdev = NULL;
>>>> - S390pciState *s = s390_get_phb();
>>>>
>>>> if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
>>>> error_setg(errp, "PCI bridge hot unplug currently not supported");
>>>
>>> Not sure whether that is an improvement (s390_get_phb() caches the
>>> value, and is called from multiple other places as well.)
>>>
>>
>> Looking up a variable that is directly passed as an argument doesn't
>> look clean to me.
>
> I think there was a reason for this caching, namely that qom resolution can
> be quite expensive. For the hotplug case this obviously does not matter but
> for all the other cases it might. So do we really want to have different
> places use different methods?
>
Caching resolution is fine (as that is expensive), caching a downcast is
as far as I remember not necessary. Especially, as you said, for hotplug
handlers.
Anyhow, if there are strong feelings to this change, I can drop this
patch. There are certainly more important things to do in zPCI hotplug code.
--
Thanks,
David / dhildenb
- [Qemu-devel] [PATCH v1 1/4] s390x/zpci: drop msix.available, (continued)
- [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, David Hildenbrand, 2018/11/05
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, Cornelia Huck, 2018/11/05
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, David Hildenbrand, 2018/11/05
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, Christian Borntraeger, 2018/11/05
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge,
David Hildenbrand <=
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, Collin Walling, 2018/11/07
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, Cornelia Huck, 2018/11/08
- Re: [Qemu-devel] [PATCH v1 2/4] s390x/zpci: use hotplug_dev instead of looking up the host bridge, David Hildenbrand, 2018/11/08
[Qemu-devel] [PATCH v1 4/4] s390x/zpci: properly fail if the zPCI device cannot be created, David Hildenbrand, 2018/11/05
Re: [Qemu-devel] [PATCH v1 4/4] s390x/zpci: properly fail if the zPCI device cannot be created, Collin Walling, 2018/11/07
Re: [Qemu-devel] [PATCH v1 4/4] s390x/zpci: properly fail if the zPCI device cannot be created, Cornelia Huck, 2018/11/08