tree 8d1308ea8e0e7ef246f98d3e28f662a2a3f28d5c
parent 7997e322ab4b15661355ca3bab30366922709177
author Juan Cruz Viotti <juan@balena.io> 1553081681 +0000
committer Nathan Hjelm <hjelmn@me.com> 1554478132 -0600

darwin: Retry IOCreatePlugInInterfaceForService on failure

We have a case where a device might not be detected by libusb if we plug
it after initializing the library. We were able to reproduce this issue
pretty consistently on a Mac Mini and several MacBook Pros running very
recent macOS versions (Mojave) using the Balena Fin board
(https://www.balena.io/fin/). I don't know if this happens with other
USB devices.

Enabling debug output revealed the following:

```
[ 7.901582] [00004f07] libusb: debug [darwin_get_cached_device] finding cached device for sessionID 0x2a9b5279f04
[ 7.901764] [00004f07] libusb: debug [darwin_get_cached_device] matching sessionID 0x2a9b5279f04 against cached device with sessionID 0x17dbd029b6a
[ 7.901798] [00004f07] libusb: debug [darwin_get_cached_device] matching sessionID 0x2a9b5279f04 against cached device with sessionID 0x1688763269f
[ 7.901818] [00004f07] libusb: debug [darwin_get_cached_device] matching sessionID 0x2a9b5279f04 against cached device with sessionID 0x4c0aefaa
[ 7.901831] [00004f07] libusb: debug [darwin_get_cached_device] matching sessionID 0x2a9b5279f04 against cached device with sessionID 0x0
[ 7.901845] [00004f07] libusb: debug [darwin_get_cached_device] caching new device with sessionID 0x2a9b5279f04
[ 7.903377] [00004f07] libusb: debug [darwin_device_from_service] could not set up plugin for service: out of resources
[ 8.029152] [00000307] libusb: debug [libusb_get_device_list]
```

The "out of resources" error comes from
`IOCreatePlugInInterfaceForService` which will apparently return this
error if the `Start` method of the interface is not success (see
https://github.com/opensource-apple/IOKitUser/blob/b80a5cbc0ebfb5c4954ef6d757918db0e4dc4b7f/IOCFPlugIn.c#L232).

Retrying `IOCreatePlugInInterfaceForService` makes it work for me.

Closes #542

Signed-off-by: Juan Cruz Viotti <juan@balena.io>
Signed-off-by: Nathan Hjelm <hjelmn@me.com>