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From: Juergen Gross <jgross@suse.com>
To: Chunyan Liu <cyliu@suse.com>, xen-devel@lists.xen.org
Cc: george.dunlap@eu.citrix.com, Ian.Jackson@eu.citrix.com,
	Simon Cao <caobosimon@gmail.com>,
	wei.liu2@citrix.com, ian.campbell@citrix.com
Subject: Re: [PATCH V4 3/7] libxl: add pvusb API
Date: Thu, 11 Jun 2015 17:00:46 +0200	[thread overview]
Message-ID: <5579A29E.5090007@suse.com> (raw)
In-Reply-To: <1433906441-3280-4-git-send-email-cyliu@suse.com>

On 06/10/2015 05:20 AM, Chunyan Liu wrote:
> Add pvusb APIs, including:
>   - attach/detach (create/destroy) virtual usb controller.
>   - attach/detach usb device
>   - list usb controller and usb devices
>   - some other helper functions
>
> Signed-off-by: Chunyan Liu <cyliu@suse.com>
> Signed-off-by: Simon Cao <caobosimon@gmail.com>

I've tested the patches with an old SUSE pvusb backend and my new one.

While all cases I tried worked with xm, the xl variant had some problems
with both backends, the new one being worse. I suspect especially this
patch to be faulty, as it has IMHO a potential structural problem: when
trying to attach a USB device without having created a usb-controller
for the domain, an asynchronous libxl-operation will itself call
another async operation.
The second async operation is being called with ao_how being NULL, but
I'm not sure whether this is allowed (libxl_internal.h comments are not
clear for me regarding such a scenario).

libxl_device_usb_add()
   AO_CREATE(ctx, domid, ao_how)
   libxl__device_usb_add()
     libxl__device_usb_setdefault()
       libxl_device_usbctrl_add_common()
         AO_CREATE(ctx, domid, NULL)

Tests with the new backend:

What I'm seeing is an error message that the controller couldn't be
assigned and the device would fail, too.

The real result, however, is an assigned controller, but no device.
Manual assignment of the device succeeds afterwards.

doing "xl usb-ctrl-attach" and then "xl usb-attach" is working, too.

Assigning a device via config file fails always (binding of device to
backend failed).


Tests with the old backend:

All tests but assigning a device via config file worked (again the
same binding error).


As I'm currently trying to write a new pvusb backend in qemu, I don't
want to investigate the xl problems with the new kernel backend. I
suspect some timing differences between old and new kernel drivers
leading to the different results.

As the qemu variant wouldn't need any driver rebinding in libxl (qemu
is handling this by itself) I wouldn't be worried too much about the
config file problem.

If, however, the nested usage of AO_CREATE is forbidden, this has to
be changed, of course.


Juergen

  reply	other threads:[~2015-06-11 15:00 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-10  3:20 [PATCH V4 0/7] xen pvusb toolstack work Chunyan Liu
2015-06-10  3:20 ` [PATCH V4 1/7] libxl: export some functions for pvusb use Chunyan Liu
2015-06-11 16:08   ` Ian Jackson
2015-06-11 16:28     ` Wei Liu
2015-06-12 15:14       ` Ian Jackson
2015-06-10  3:20 ` [PATCH V4 2/7] libxl_read_file_contents: add new entry to read sysfs file Chunyan Liu
2015-06-11 16:16   ` Ian Jackson
2015-06-12  7:00     ` Chun Yan Liu
2015-06-12 15:11       ` Ian Jackson
2015-06-10  3:20 ` [PATCH V4 3/7] libxl: add pvusb API Chunyan Liu
2015-06-11 15:00   ` Juergen Gross [this message]
2015-06-11 16:07     ` Ian Jackson
2015-06-11 16:42   ` Ian Jackson
2015-06-12  7:39     ` Chun Yan Liu
2015-06-12  8:06       ` Chun Yan Liu
2015-06-12 11:22       ` Ian Jackson
2015-06-15 14:17   ` George Dunlap
2015-06-15 14:25     ` Jürgen Groß
2015-06-15 14:34       ` George Dunlap
2015-06-15 18:26         ` Juergen Gross
2015-06-16 10:30           ` George Dunlap
2015-06-16 10:51             ` Juergen Gross
2015-06-16 11:11               ` George Dunlap
2015-06-16 11:19                 ` Juergen Gross
2015-06-16 11:23                   ` George Dunlap
2015-06-16 11:44                     ` Ian Jackson
2015-06-17 11:24                       ` Ian Campbell
2015-06-18 11:50                         ` George Dunlap
2015-06-18 12:08                         ` George Dunlap
2015-06-18 13:03                           ` Juergen Gross
2015-06-22 13:29                           ` Proposed plan for libxl USB interface (was Re: [PATCH V4 3/7] libxl: add pvusb API) George Dunlap
2015-06-22 14:14                             ` Juergen Gross
2015-06-22 14:22                             ` Ian Jackson
2015-06-23  2:42                             ` Chun Yan Liu
2015-06-23  2:43                             ` Chun Yan Liu
2015-06-23  2:44                             ` Chun Yan Liu
2015-06-16 10:41     ` [PATCH V4 3/7] libxl: add pvusb API Ian Jackson
2015-06-16 10:56       ` Jürgen Groß
2015-06-16 11:03         ` George Dunlap
2015-06-16 11:10         ` Ian Jackson
2015-06-16 11:25           ` Juergen Gross
2015-06-16 11:45             ` George Dunlap
2015-06-16 12:02               ` Ian Jackson
2015-06-16 13:19                 ` George Dunlap
2015-06-16 13:32                   ` Juergen Gross
2015-06-16 13:37                   ` [PATCH V4 3/7] libxl: add pvusb API [and 1 more messages] Ian Jackson
2015-06-16 14:41                     ` George Dunlap
2015-06-16 15:58                       ` Sander Eikelenboom
2015-06-16 15:59                       ` Ian Jackson
2015-06-16 16:34                         ` George Dunlap
2015-06-17  3:59                           ` Juergen Gross
2015-06-17 10:27                             ` George Dunlap
2015-06-18  6:24                               ` Chun Yan Liu
2015-06-16 11:45             ` [PATCH V4 3/7] libxl: add pvusb API Ian Jackson
2015-06-16 13:06               ` Juergen Gross
2015-06-16 13:09                 ` George Dunlap
2015-06-16 13:23                   ` Juergen Gross
2015-06-16 13:29                     ` George Dunlap
2015-06-16 13:49                       ` Juergen Gross
2015-06-16 14:06                         ` George Dunlap
2015-06-16 14:20                           ` Juergen Gross
2015-06-16 14:37                             ` George Dunlap
2015-06-17 11:34                             ` Ian Campbell
2015-06-17 11:40                               ` Juergen Gross
2015-06-18  6:20                               ` Chun Yan Liu
2015-06-18  7:02                                 ` Juergen Gross
2015-06-18  8:50                                   ` Ian Campbell
2015-06-18 13:02                                     ` Juergen Gross
2015-06-16 15:38             ` George Dunlap
2015-06-16 11:01       ` George Dunlap
2015-06-16 11:12         ` Ian Jackson
2015-06-16 11:21           ` George Dunlap
2015-06-16 16:32             ` Ian Jackson
2015-06-16 16:39               ` George Dunlap
2015-06-16 16:51                 ` Ross Philipson
2015-06-17  4:03                   ` Jürgen Groß
2015-06-17 13:48                     ` Ross Philipson
2015-06-15 17:47   ` George Dunlap
2015-06-23 10:18     ` Chun Yan Liu
2015-06-23 11:29       ` George Dunlap
2015-06-24  2:26         ` Chun Yan Liu
2015-06-10  3:20 ` [PATCH V4 4/7] libxl: add libxl_device_usb_assignable_list API Chunyan Liu
2015-06-10  3:20 ` [PATCH V4 5/7] xl: add pvusb commands Chunyan Liu
2015-06-12  7:37   ` Juergen Gross
2015-06-12  8:03     ` Chun Yan Liu
2015-06-12  8:22       ` Juergen Gross
2015-06-10  3:20 ` [PATCH V4 6/7] xl: add usb-assignable-list command Chunyan Liu
2015-06-10  3:20 ` [PATCH V4 7/7] domcreate: support pvusb in configuration file Chunyan Liu

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