[libvirt] [PATCH 2/3] qemu: make use of usb search function to initialize usb devices

[Guannan Ren]

On 05/05/2012 03:36 AM, Eric Blake wrote:
> On 05/04/2012 02:25 AM, Guannan Ren wrote:
>> refactor qemuPrepareHostdevUSBDevices function, make it focus on
>> adding usb device to activeUsbHostdevs after check. After that,
>> the usb hotplug function qemuDomainAttachHostDevice also could use
>> it.
>>
>> expand qemuPrepareHostUSBDevices to perform the usb search,
>> rollback on failure.
>> ---
>>   src/qemu/qemu_hostdev.c |  117 +++++++++++++++++++++++++++-------------------
>>   src/qemu/qemu_hostdev.h |    3 +-
>>   2 files changed, 70 insertions(+), 50 deletions(-)
>> diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c
>> index b98fd8f..0cb89a6 100644
>> --- a/src/qemu/qemu_hostdev.c
>> +++ b/src/qemu/qemu_hostdev.c
>> @@ -565,13 +565,50 @@ qemuPrepareHostPCIDevices(struct qemud_driver *driver,
>>   int
>>   qemuPrepareHostdevUSBDevices(struct qemud_driver *driver,
>>                                const char *name,
>> -                             virDomainHostdevDefPtr *hostdevs,
>> -                             int nhostdevs)
>> +                             usbDeviceList *list)
>>   {
>> -    int ret = -1;
>>       int i;
>> +    usbDevice *tmp;
>> +
>> +    for (i = 0; i<  usbDeviceListCount(list); i++) {
> Thankfully, usbDeviceListCount() is O(1); if it were O(n) then you would
> have a quadratic loop.  Still, it is slightly faster to factor the
> function call out of the for loop.  On the other hand, right now we
> aren't using gcc's attribute((pure/const)) because the warnings in gcc
> 4.6 were buggy; if we were to use that, then usbDeviceListCount() would
> already be marked and there would be nothing to factor out.  So, this is
> fine as is, and we can save the optimization for a future day when we
> rely on gcc 4.7 to help us mark the attributes where needed.

       I combine the two patches 2/3, 3/3, and made a small modification
    on invoking usbDeviceListCount() on V5.

...

+    unsigned int count;
+    usbDevice *tmp;
+
+    count = usbDeviceListCount(list);
+
+    for (i = 0; i<  count; i++) {
...



>
> Unfortunately, this failed to compile on its own:
>
> qemu/qemu_hotplug.c: In function 'qemuDomainAttachHostDevice':
> qemu/qemu_hotplug.c:1137:9: error: passing argument 3 of
> 'qemuPrepareHostdevUSBDevices' from incompatible pointer type [-Werror]
> qemu/qemu_hostdev.h:39:5: note: expected 'struct usbDeviceList *' but
> argument is of type 'struct virDomainHostdevDef **'
> qemu/qemu_hotplug.c:1137:9: error: too many arguments to function
> 'qemuPrepareHostdevUSBDevices'
> qemu/qemu_hostdev.h:39:5: note: declared here
>
> But since applying patch 3/3 fixes the failure:
>
> ACK if you squash 2/3 and 3/3 into a single patch, so that the total
> series is only 2 patches instead of 3.
>

     Thanks for these reviews and comments.

     Guannan Ren