Re: [Xen-devel] [PATCH v3 2/5] libxl: add new pvusb backend "qusb" provided by qemu

[Juergen Gross <jgross@xxxxxxxx>]

On 25/03/16 03:23, Chun Yan Liu wrote:
> 
> 
>>>> On 3/23/2016 at 08:24 PM, in message
> <1458735847-9448-3-git-send-email-jgross@xxxxxxxx>, Juergen Gross
> <jgross@xxxxxxxx> wrote: 
>> Add a new pvusb backend type "qusb" which is provided by qemu. It can 
>> be selected either by specifying the type directly in the configuration 
>> or it is selected automatically by libxl in case there is no "usbback" 
>> driver loaded. 
>>  
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> 
>> --- 
>>  docs/man/xl.cfg.pod.5                |  11 +++- 
>>  tools/libxl/libxl_device.c           |   3 +- 
>>  tools/libxl/libxl_dm.c               |   8 +++ 
>>  tools/libxl/libxl_internal.h         |   1 + 
>>  tools/libxl/libxl_pvusb.c            | 102 
>> +++++++++++++++++++++++++++-------- 
>>  tools/libxl/libxl_types.idl          |   1 + 
>>  tools/libxl/libxl_types_internal.idl |   1 + 
>>  7 files changed, 101 insertions(+), 26 deletions(-) 
>>  
>> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h 
>> index fc7bdab..2db8b1b 100644 
>> --- a/tools/libxl/libxl_internal.h 
>> +++ b/tools/libxl/libxl_internal.h 
>> @@ -22,6 +22,21 @@ 
>>   
>>  #define USBHUB_CLASS_CODE 9 
>>   
>> +static int usbback_is_loaded(libxl__gc *gc) 
>> +{ 
>> +    int r; 
>> +    struct stat st; 
>> + 
>> +    r = lstat(SYSFS_USBBACK_DRIVER, &st); 
>> + 
>> +    if (r == 0) 
>> +        return 1; 
>> +    if (r < 0 && errno == ENOENT) 
>> +        return 0; 
>> +    LOGE(ERROR, "Accessing %s", SYSFS_USBBACK_DRIVER); 
>> +    return -1; 
>> +} 
>> + 
>>  static int libxl__device_usbctrl_setdefault(libxl__gc *gc, uint32_t domid, 
>>                                              libxl_device_usbctrl *usbctrl) 
>>  { 
>> @@ -36,7 +51,8 @@ static int libxl__device_usbctrl_setdefault(libxl__gc *gc, 
>>  
>> uint32_t domid, 
>>   
>>      if (usbctrl->type == LIBXL_USBCTRL_TYPE_AUTO) { 
>>          if (domtype == LIBXL_DOMAIN_TYPE_PV) { 
>> -            usbctrl->type = LIBXL_USBCTRL_TYPE_PV; 
>> +            usbctrl->type = usbback_is_loaded(gc) ? LIBXL_USBCTRL_TYPE_PV 
> The condition should be (usbback_is_loaded(gc) > 0)?
> usbback_is_loaded(gc) < 0 means lstat error, cannot determine if the
> usbback driver is loaded.

Good point. I think in error case I should rather abort the operation.

Thoughts?


Juergen

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