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

[Alan Stern]

Alan:

There's a problem with the tty->ops->shutdown method.  It needs to
release the last port reference owned by the current tty.  But when was
that reference originally acquired?  Evidently during the first time
serial_open() was called for the current tty.

The problem is that serial_open() has no way to know if a particular 
invocation is the first one for this tty!  The ASYNCB_INITIALIZED flag 
doesn't help, because it might not get set during the first call (i.e., 
if an error occurs).

To do this right, we need a flag in the tty_struct or the tty_port
which serial_open() can set when acquiring that first reference and
shutdown method can clear.  Should I add such a flag?

Alan Stern

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