[libusb] #140: Windows backend hangs on XP using multiple threads.

[libusb T. <tr...@li...>]

#140: Windows backend hangs on XP using multiple threads.
--------------------+-----------------------------------------
 Reporter:  mozmck  |       Owner:
     Type:  defect  |      Status:  new
Milestone:          |   Component:  libusb-1.0 Windows backend
 Keywords:          |  Blocked By:
   Blocks:          |
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 I have a program with 2 threads.  One thread submits OUT transfers, and
 another thread calls libusb_handle_events_completed().  This event thread
 also submits an IN transfer which is re-submitted in it's callback.

 This code works in Linux, but hangs the program in windows after a short
 amount of time.  I have only tried this in WinXP because that's all I
 have.

 Here is a brief section of the debug output:

 libusb: 1.351944 debug [] handling I/O completion with errcode 0
 libusb: 1.361958 debug [] matched endpoint 01 with interface 0
 libusb: 1.361958 debug [] could not duplicate handle for CancelIo - using
 original one
 libusb: 1.361958 debug [] writing 60 bytes
 libusb: 1.361958 debug [] add fd 6 events 4
 libusb: 1.361958 warning [] Unable to cancel I/O that was started from
 another thread
 libusb: 1.361958 debug [] transfer 009D2928 has callback 00464F9F
 libusb: 1.361958 debug [] no URB with timeout or all handled by OS; no
 timeout!
 libusb: 1.361958 debug [] doing our own event handling
 libusb: 1.361958 debug [] poll() 3 fds with timeout in 60000ms
 libusb: 1.361958 warning [] invalid fd
 libusb: 1.361958 debug [] poll() returned -1
 libusb: 1.361958 error [] poll failed -1 err=9


 And here is a section up to the very end of the log when it hung:

 libusb: 1.392001 debug [] checking fd 3 with revents = 0000
 libusb: 1.392001 debug [] checking fd 4 with revents = 0001
 libusb: 1.392001 error [] could not find a matching transfer for fd 4
 libusb: 1.392001 error [] backend handle_events failed with error -5
 libusb: 1.392001 debug [] no URB with timeout or all handled by OS; no
 timeout!
 libusb: 1.402016 debug [] matched endpoint 01 with interface 0
 libusb: 1.402016 debug [] could not duplicate handle for CancelIo - using
 original one
 libusb: 1.402016 debug [] writing 60 bytes
 libusb: 1.402016 debug [] add fd 7 events 4
 libusb: 1.402016 debug [] doing our own event handling
 libusb: 1.402016 debug [] poll() 5 fds with timeout in 60000ms
 libusb: 1.402016 debug [] poll() returned 3
 libusb: 1.402016 debug [] checking fd 3 with revents = 0000
 libusb: 1.402016 debug [] checking fd 4 with revents = 0001

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Ticket URL: <https://libusb.org/ticket/140>
libusb <https://libusb.org/>
C library for writing portable USB drivers in userspace