Re: [libusb] Timeouts then Access Denied Errors on Win 7

[Richard B. <ra...@lu...>]

>
>
> No, you have received no "consensus" of any kind.  You're going to need
> to figure out what combination of things triggers this.  Are the calls
> to libusb_get_device_list in a separate thread?  Does this happen only
> when you call libusb_get_device_list while one of your reads is
> outstanding?  If this is caused by some interference between the two
> processes, that's a problem that can be tackled, but it's going to take
> some analysis.
>
> As it is, you have nothing but vague suspicions.
>
>
I know I haven't received a "consensus", that's why I was asking...

The program interacts with libusb within a single thread.  Calls to
libusb_get_device_list never occur when a bulk transfer read or write is
occurring.  As it was I had no suspicions at all as to the cause of the
problem, I was just repeating what Xiaofan had said the cause of the
problem might be.

Some less-vagues supsicions though... Based on the absence of certain
error/warning messages in the debug log, I believe the error is triggered
at calls to one of the following places:


https://github.com/libusb/libusb/blob/ada59db186aa95215158129db8cd42e079daff07/libusb/os/windows_usb.c#L118

https://github.com/libusb/libusb/blob/ada59db186aa95215158129db8cd42e079daff07/libusb/os/windows_usb.c#L123

https://github.com/libusb/libusb/blob/ada59db186aa95215158129db8cd42e079daff07/libusb/os/windows_usb.c#L1412

The debug message associated with the last place (line 1412) happens
regularly -- before any errors with devices occur.  Additionally, the
devices with which the problem occurs are not HID devices.  So its probably
coming from CHECK_WINUSBX_AVAILABLE?  But I wouldn't expect the sub_api to
somehow become uninitialized after being initialized correctly at the
start... And there are no errors in the log that would indicate this.

I'll see if I can make a simple test program that reproduces this
consistently.