Comment 10 for bug 700316

In my specific case, the devices I use are ZWave, and they have this habit of sharing USB ID with genuine serial cables.

But that doesn't matter. Network-manager made one of my genuine serial cables unusable, which means that even if it had an old serial modem attached it would probably prevent me from using it.

I don't exactly have the time to dig deeper, but my intuition says that some weird ioctls may be doing this. For this to happen, some new modem probing code, probably specific to a single modem out there, is at fault. At least that's what I'd be looking for. Confuse the device enough and it will fail to return from "open" (probably frozen, needs to be reinitialized).

I need to run another test: get one USB device network-manager-ized, then remove network-manager and add a second usb serial device. If there's nothing to probe it, it should be fine. If it isn't, usbserial has a problem (too). I hope this isn't the case though.