Messages in this thread | | | Date | Sun, 11 Mar 2012 00:21:10 +0100 | From | Richard Weinberger <> | Subject | Re: TTY: tty_port questions |
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Am 10.03.2012 23:51, schrieb Jiri Slaby: > On 03/10/2012 11:26 PM, Richard Weinberger wrote: >> Hi! > >> While moving UML's console driver to tty_port some strange things >> happened. So, I have a few questions. :-) > >> The original driver did not implement tty_operations->hangup(). If >> I implement it and call tty_port_hangup(), as Alan suggested, the >> login fails on all TTYs except tty0. It fails because the opened >> TTY returns EIO upon read()/write() after /bin/login called >> vhangup(). > >> The call chain is: vhangup() -> tty_vhangup_self() -> tty_vhangup() >> -> __tty_hangup() > >> Within __tty_hangup() something happens that I don't fully >> understand: > >> if (cons_filp) { if (tty->ops->close) for (n = 0; n < closecount; >> n++) tty->ops->close(tty, cons_filp); } else if (tty->ops->hangup) >> (tty->ops->hangup)(tty); > >> Login on tty0 works because cons_filp is not NULL and >> tty->ops->close() is called. On the other hand login fails on every >> other TTY because cons_filp remains NULL and the TTY hangs up. > >> Is there something missing in my hangup function? > >> If I omit tty_operations->hangup() and leave it, like the old >> driver, NULL non-tty0 TTYs cannot be opened. (getty terminates >> immediately because it cannot open any TTY.) open() retuns -EIO >> because the TTY_CLOSING is set in tty->flags. > >> How can this be? > > Hmm, it looks like some process is sitting on a TTY which was hung. > And the system offers this hung TTY to others on further opens. Could > you check that there is no process with open TTY after the vhangup? >
"lsof | grep tty" does not show anything else than tty0. :-\
Thanks, //richard
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