Re: 2.6.31-rc5 regression: Oops when USB Serial disconnected while in use

Alan Cox
2009-08-21T15:48:09Z

> Alan, related to this problem is the fact that usb_serial_driver
> doesn't include a "hangup" method. I'm not sure that making
> serial_hangup() call serial_do_down() is correct, but if it is then
> shouldn't we call port->serial->type->open() afterwards? Otherwise the
> lower driver can't know that the port is still open.

After a hangup the port isn't open (at the physical level anyway). It may
be re-opened by another open() call later but the original user lost
access to it and shouldn't touch the h/w post hangup completion.

> Furthermore, shouldn't we check ASYNCB_INITIALIZED in serial_close()?

Possibly - I was in the middle of debugging the newest bits when Linus
annoyed me. Certainly there are issues in the current code if you get
a hangup while waiting for open to complete. I fixed that in the patches
I sent Greg but didn't finish debugging it.