So now, when we handle CLOSING flag, there is no point to hold
port->mutex over the start of uart_close.
Yes, there are still several things to reason about:
* port->count etc is and always was protected by a spinlock
* ->stop_rx is protected by a spinlock. Otherwise it would
race with interrupts.
* uart_wait_until_sent -- that one is already called without
port->mutex from set_termios and tty_set_ldisc. Should anything
be protected there, it would be tx_empty. And by a spinlock.
8250 does this internally...
This step is needed to fix system stalls. To not create an AB-BA lock
dependency (see next patches).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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